Indian Railways AC Traction Manual Volume 11 Part 1 PDF

CHAPTER IX PREPARATION FOR CONMSSIONING 20900 Introduction Prior to commissioning new Railway Electrification, schemes, detailed preparation work is a necessary pre- requisite. While instructions are issued separately in technical manuals of various equipments, salient points in respect of the following major heads are outlined in this chapter. I Traction sub-stations II Transmission lines and 25 kV feeders III Protective equipment IV Switching Stations V Remote Control 4quipment VI Overhead equipment VII General This chapter is devoted to the technical aspects of work which call for attention during inspections, tests and trials before energization.. Chapter X deals with procedures in connection with energization and commissioning and putting the assets into beneficial use. 20901 Reference to Rules and Statutory Rules The safety of travelling public, railway staff and property shall be ensured by strict compliance with the rules laid down in. i) Indian Electricity Act 1910 (latest revision), ii)Indian Electricity Rules (latest edition), iii)Indian Railway Act (as amended from time to time), iv)General Rules for Indian Railways and associated Subsidiary Rules prescribed by Zonal Railways, v)Indian Railways' Schedule of Dimensions, vi)The Rules for Opening of a Railway or Section of a Railway for Public Carriage of Passengers, 1935 (as amended from time to time), vii)Bonding and Earthing Code, Code for Earthing for Traction Installations and Regulations for Power line Crossings, viii) Relevant IS or IRS specifications and code of practices for various equipment. INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 During the preparations for commissioning, the provisions of all these rules shall be kept in view. Wherever extracts and Appendix etc., of the rules have been included from these rules in the ACTM, the figures and contents would automatically get amended with dates of amendments. Methods/procedures indicated in the manual are only for guidance and may be modified as per latest methods/standards prescribed by RDSO/approved by CEE. 20902 Pre-Commissioning Inspections 1 Pre-commissioning inspections and tests cover two distinct parts, viz. a) Detailed inspection at the level of the ACE and Senior Subordinates, and b) General inspection at the level of the Divisional Officers. These two inspections are primary Inspections covering all the Installations and are independent of any inspections which may be carried out by Administrative officers. 2, Officers and staff of various sections (Departments) in the Division should associate themselves with the field work during construction, acquaint themselves with the Installations, satisfy themselves about high standards and quality of work and get the defects noticed rectified then and there, while work is in progress. 3. The departmental agencies executing the work in the construction organization shall also keep constant liaison with their counterparts on the open line, who will be responsible for the maintenance of assets created by the construction unit. 20903 Defect and Deficiency Lists When the work is declared as having been completed and ready for Inspection, the field officers and Senior subordinates of the open line, along with their counterparts of the construction unit and representative of contractors, if any, will carry out joint checks. The checks should be thorough and cover every part of the Installation. In making these checks the latest drawings should only be used (superseded versions can be misleading and should be positively avoided). All defects noticed during such joint checks should be rectified before the sections are taken over by the open line maintenance organization. The defects will be categorized in three types and jointly signed lists be prepared accordingly: Category A - Defects concerning vital safety items and serious shortcomings, which must be rectified before even test charge. Category B - Defects , not affecting safety though their rectification before cornrnissioning is essential for trouble free working of electric train service. Category C – Minor defects, which need not hold up commissioning and can be rectified after commissioning in a reasonable time. During the preparatory period, these lists should be constantly reviewed jointly and progress of rectification to be done by construction organization be watched. INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1. TRACTION SUB-STATIONS 20904 Planning of Power Supply 1. Sub-stations play a vital role in electric traction and, therefore, the need for considerable care during erection and commissioning cannot be over-emphasized. A high standard of workmanship Is essential and the pre- commissioning tests should be systematically carried out by competent staff, using dependable and calibrated instruments. 2. When a long stretch of section of the railway is sanctioned for electrification, detailed planning of section by section energizing be undertaken and commissioning for commercial operation of electric traction over appropriate sections with partial change of traction be decided. Keeping in view the fact that 100% traffic cannot be switched over till a viable section of the Railway is completed, the order in which the sub-stations should be brought on line should be decided by CEE in consultation with RE and operating branch. This decision should take into account the reliability of supply for the. energized section, the tariff structure and the commitments in regard to contract demand and minimum guarantee to supply authorities. 3. The supply authorities may then be advised the dates by which power supply will be needed at the various sub-stations. Agreements may be entered into at appropriate time to make sure that the supply authorities do not delay the work on their part and have adequate time to complete the construction of their works for connecting the substation to the grid. 4. The phasing diagram, deciding which phases of SEB's transmission lines will be connected at different sub- stations should be finalized in consultation with supply authorities for the entire section of the Zonal Railway planned for electrification, keeping in view power supply on adjacent railway systems. The connection of the substations to the transmission lines should be in cyclic order so that the load due to electric traction on the grid system is well balanced and remain within the permissible limits of unbalance. 5. The power supply to traction substation is connected through transmission line, which often cross the track. The application for the 'Track Crossing' should therefore be processed well in advance through Sr. DEE (G), to avoid delays in the supply connection. 20905 Commissioning of Traction Transformers During the preparation for commissioning of transformers at traction sub-stations In addition to manufacturer's instructions, the following steps shall be taken: i) Drying out of transformer shall be undertaken as per the procedure laid down. (Refer para 20208) ii) Tap-changing mechanism shall be checked for being in perfect operating condition, both electrically and mechanically. Ratio test should also be done in this procedure. (Refer para 20206) iii) Transformer bushings should be paid special attention to ensure that the manufacturer seal is intact and the bushings are in excellent condition. The Insulation Resistance of the bushing should be around 10,000 Meg Ohm. iv) All gaskets should be properly compressed and tight fitted. No leakage of oil should be visible from valves, pipe joints, gauge glass, radiators or any other parts of transformer. The welded joints should also be checked for for seepage if any. V) For a sub-station with more than one transformer, they should preferably be identical. The polarity on both should be checked. Vi) The oil filled in transformer should be fully de-aerated to avoid false operation of Buchholz relay. INDIAN RAILWAYS - AC TRACTION MANUAL VOLUME 11 PART 1 vii) The Buchholz relay should be erected as per instructions of the makers and tested for correct operation. vii) All accessories like silica gel breather vent pipe, explosion vent diaphragm, circulating oil pump and special cooling equipment, if any should be checked. ix) In addition to Buchholz relay, (Refer para 20214) other protective devices provided for the protection of transformer (Refer para 20212, 20213) should be examined and checked carefully and tested after erection at site. Y.) Earthing of transformers and its neutral terminal shall be done in accordance with the "Code of Practice for Earthing of Power Supply Installations" (Appendix 111). 20906 Precautions During Commissioning of Traction Transformer While working on traction transformers, the following special precautions should be taken by all the staff: 1. It is very important that any one working on a transformer with any of its covers open should remove all loose articles from his clothing such as pens, pencils, watches, money, smoking articles, tools particularly if they are oily, as they are liable to slip and fall into the transformer in the course of work. The number of men working on top should be restricted to the minimum. If tools have to be used they should be fastened by lengths of strings to the workers' wrists or to the tank rim. 2. Moisture lowers the dielectric strength of oil, and hence every possible precaution should be taken to prevent its entry. Sweat on hands and face should be wiped off frequently by a dry cloth and tools should be kept clean and dry, especially when coming in contact with oil. Another source of entry of moisture into the tank is by condensation. If at transformer is at a lower temperature than its surroundings, condense will form on the exposed surfaces. Transformer should, therefore, be at or above the ambient temperature before being opened for work at any time. If any cleaning or wiping is necessary, this should be done with clean, dry oil using soft, non-fluffy cloth, and never by using cotton waste. 20907 Tests on Transformer Windings (i) Insulation resistance readings should be recorded with a 2500 V or 5000 V megger. The following are the minimum permitted values at an ambient temperature of 30 degree centigrade. Temperature has a material influence on insulation resistance, and therefore the test should not be conducted when oil is hot. 2000 Mega Ohm between EHV winding and earth. 400 Mega Ohm between 25 kV winding and earth. 2500 Meg Ohm between EHV and 25 kV windings. ii) Test on insulation: The test consists of applying dc high voltage (2500 V or 5000 M, with the help of a megger, continuously between winding and earth, and noting the insulation resistance at the end of 10 sec, 60 see and 600 sec. To maintain constant voltage, a motor-driven megger is preferable. The polarization ratios R60/RIO and R600/R60 should not he less than 1.4 and 1.2 respectively. (RIO, R60, R600 are the Insulation Resistance values after 10 sec, 60 see and 600 sec respectively). iii) Phasing out test : This is comparatively easy, as single phase transformers alone are provided at traction sub station : if both the transformers install at a sub station are of identical manufacture the terminal connections will be identical. Nevertheless , the correctness of polarity should be checked applying 400 V across the primaries in an identical manner and measuring the relative voltage between the two secondaries of transformers after connecting one terminal of one secondary with the corresponding terminal of the other. INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 178 iv) oil test : The tests on transformer oil should be done In accordance with IS-1866 for oil in use (See Annexure 2.03 Chapter 11). 20908 Circuit Breakers and Interruptors The installation of circuit breakers and interruptors should be carefully done as per Instruction Manual of makers. The following special checks may be made. Cheek, first of all, if the circuit breaker mounting is quite vertical and the base firmly secured. Examine the operating mechanism in the weatherproof housing for cleanliness, free movement of rollers, bearings and sliding surfaces, which should be very lightly oiled. Open and close the breaker several times to cheek that everything is working smoothly. Make sure that all pins, locking plates and split-pins are in place. On the electrical side, examine the condition of the wiring, its insulation resistance and tightness of the terminal screws. Check if the opening and closing solenoid or motor when electrically operated does operate satisfactorily with battery voltage 20 per cent less and 1 0 per cent more than the rated voltage. Check also the manual operation and record the operating time for closing and opening. Examine whether the heater in the equipment cabinet is in working order. Observe if the auxiliary contacts are clean and good and the terminal block well secured. Select a few circuit breakers at random to inspect the Interior of the arc-extinction chamber to make sure that the main circuit breaker contacts are in excellent condition and their alignment good, but taking care not to contaminate the parts. The parts handled should be washed thoroughly well with good transformer oil and put back and oil level restored. Check and record the dielectric strength of oil in every circuit breaker, taking out the oil through the sampling cock. If the break-down voltage (BDM is less than 40 kV, oil will have to be dried out. This is easily done by a small portable oil purifier having, a capacity of 200 liters per hour. After drying- out, repeat the BDV test, taking the precautions described in Chapter 11. Examine particularly if there is any strain on the circuit breaker porcelain housing because of misalignment or rigidity of the connection from its terminals to the busbars. Usually this is made through flexible connectors; nevertheless, it is wise to check the position of the connecting leads when the bolts are loosened. Make sure also that the metal-to-metal contact is perfect at the terminal connections. Any imperfection here will result in overheating of the terminal which may even lead to eventual fracture of the housing itself. It is best to measure the contact resistance by "Ductor" or similar low-resistance-reading instrument. Finally, cheek the general condition of the equipment, finish and weather-proof-ness of the cabinet and whether it is Insect-proof, whether fuses are intact, and if the operation counter, where provided, works properly and if the metal supports and frame are well earthed. 20909 Isolators Examine the insulators carefully for any surface cracks and make sure if the surface is clean. Check operation of isolator manually to see if the movement is free and smooth, and if the switch blades are fully open or fully closed when the handle is locked at the top or bottom position. Examine the contacts and cheek if the spring pressure is adequate and blades make full contact. Cheek terminal connections, preferably the a "Ductor", Examine whether the interlocking between the circuit breaker and its associated Isolator functions properly and the isolator frame is solidly connected to earth by two independent connections. For interlocking scheme for EHV and 25 kV CBs & isolators, reference may be made to RDSO Drawing(ETI/PSI/5212). 20910 Current and Potential Transformers Check and record the insulation resistance of primary and secondary to earth and between primary and secondary.Check oil level in PT if it is not of the sealed type as also its dielectric strength. Top up the oil drawn for test. Make INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 sure that the terminal connections are well made preferably recording the contact resistance of CT connections by a "Ductor". The frames of the PT and CT should be well earthed by two independent connections to earth. 20911 Lightning Arrestors Make a thorough visual examination of the outer porcelain housing for hair-line cracks and chipped sheds. Clean the outer surface of all dust. The connecting leads to the arrestor should be solid and direct. The earth terminal of the lightning arrester should be connected to the general earthing main at the substation, to the transformer tank body and finally to an independent earth electrode provided very close to the arrestor. 20912 Shielding and Earthing Cheek whether the whole of the sub-station area is well protected against atmospheric surges by screening conductors strung between substation structures and solidly connected to the earth system in accordance with the approved drawing. Check visually whether the metallic casing of every sub-station equipment and the neutral terminals of the power – transformers are solidly connected to the sub-station earthing grid,and confirm that the "Code for Earthing Power Supply Installations" Appendix 111 is complied with in all respects. 20913 Busbars and Insulators A careful inspection should be, made of every insulator supporting a busbar to detect any minute cracks on the surface; paint marks or dust should be removed and the surface gloss restored. Time spent in checking the current carrying joints on busbars and terminal connections will pay ample dividends. The contact surface should be clean, smooth and without any irregularities and burrs, so that when they are tightened the area of contact is large. The pressure should also be adequate. Particular care should be taken when joints are made between two dissimilar metals like aluminium and copper. Special bimetallic fittings should be used in such cases to prevent electrolytic corrosion. Connections should be such as to produce no strain on the equipment. 20914 Clearances The minimum clearances in mm in air for live equipment shall be as under 25 KV 66kV 100kV 132kV 22OkV 1. Between phases - 630 900 1300 2400 2. Between one phase and earth for rigid connection. 500 630 900 1300 2100 3. Between any points where man may be required to stand to the nearest (a) unsecured conductor in air (mm) 3000 3500 3500 4000 5000 (b) secured condition in air (mm) 2000 - - - - 4. Min. height of busbar 3800 4600 4600 4600 5500 20915 Auxilaiary Power Supply for Traction Substations & Control Room Whenever possible, a 3 phase, 415 / 240 V, 50 Hz supply upto 100 kVA is obtained to meet the power demands for erection and commissioning of the substation. The LT control board should also have matching capacity. An INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 180 auxiliary transformer of 100 kVA, 1 -phase 25 kV / 240 V is provided to cater to the substation and control load. The station transformer should also he subjected to detailed inspection and check as for the main transformer. The control room building shall be neat, well ventilated and provided with a strong door. The control panel should have sufficient space all round to provide working space to carry out the necessary tests. 20916 Batteries & Battery Charger The Battery room should be particularly well ventilated, protected, dust-free and dry. The battery room floor and walls upto a height of 2 m should be painted with anti-sulphuric acid paint. The batteries themselves should be well supported on teakwood stands, painted with anti-sulphuric acid paint and resting on porcelain insulators to prevent leakage. Examine the log book for the period during which the battery was given its first charge and make sure that the manufacturer's instructions have been adhered to as regards the rate of charge and the number of charge and discharge cycles. Make sure there is no possibility of the battery gases reaching the equipment room. Observe the condition of the battery plates 'take specific gravity of all the cells and voltage across each cell on load. Check if all the inter-cell connectors are tight and well vaseline. Check finally if the battery fuses are of the correct capacity and there is no possibility of battery supply failure. Make sure that the alarm bell goes off if the supply is interrupted for any reason to the control panels. The battery charger should be inspected to make sure that its capacity,for normal and boost charge as well as trickle charge is sufficient and that it complies with the technical specifications, that the meters provided are indicating properly and it is complete with necessary fuses and indicating lamps. The metal easing should have two independent earths. 20917 General Inspect the substation area to make sure that it has good drainage, that it has good all-weather road as well as rail access, that the whole area is well fenced-in with lockable gates wide enough to permit entry of a motor truck. Ensure that baffle wall in between traction power transformer and suitable oil drainage arrangement with an oil soak pit has been made in accordance with IE Rule 64 (2). The numbering of transformers, isolators, circuit breakers, Incoming transmission lines and outgoing 25 kV feeder lines should be checked to see if it has been correctly done, and does correspond with the numbering scheme on the control panels at the sub-station control room , and also on the mimic diagram board at the RCC. Fire extinguishers and fire-buckets filled with sand shall be kept ready at hand. Station name-board, Danger and Caution boards, Protected Area board etc. shall be well displayed. 20918 General Inspection of Substations and Commissioning After defects observed during detailed inspection have all been rectified, the Sr. DEE (TrD) of the open line and the Dy. CEE(PSI) of RE organization shall carry out a general inspection of every part of the sub-station along With the Contractors' representative. Considering that these are high voltage installations, the inspection should be thorough. As many spot checks as possible should be conducted to ascertain the condition of the equipment and the care taken during erection. Particular attention should be paid to the safety aspects like clearances, operation of protective relays and functioning of the trip circuits and earthing. The statutory regulations such as the Indian Electricity Act and Rules should be strictly complied with and the inspecting officers shall each personally satisfy himself by tests and measurements that the installations are fit in every way to be energized and then issue a joint certificate to that effect. An application should thereafter be submitted to the CEE and the Electrical Inspector to the Railway seeking his permission, for the commissioning of the sub-station, provided power supply will be made available by the supply authority and testing of protective relays has been completed. After his sanction is received and the precautions and procedures detailed in Chapter X are complied with the substation may be commissioned. For the first three days after commissioning, the substation equipment shall be kept under careful observation by a senior and experienced supervisory official. Thereafter daily inspection should be continued for the first fortnight. INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 (181) Immediately after energization the correct operation of every protective relay shall be checked. The substation should be taken over on RC. 11. EHV TRANSMISSION LINES AND 25 kV FEEDERS LINES 20919 Detailed Inspection of Transmission Lines As soon as a section of transmission line between two substations is declared by the Contractor as ready for inspection, detailed inspection shall be carried out by the ACE (TrD) and his staff together with their counterparts on the construction organization and contractors' representatives and a joint note prepared of the observation made and tests conducted. An defects, whether major or minor, shall be arranged to be rectified immediately so that there may be no delay in energizing the transmission lines. 20920 Compliance with Rules and Approved The work shall strictly comply with Indian Electricity Act and Indian Electricity Rules, the Contract Specifications and approved including sag-tension charts, particularly in respect to clearances between ground (and other structures) to live conductors. 20921 Visual Inspection This will cover every mast location and crossing across railway tracks, roads etc., special attention being paid to workmanship, completeness of installations and cleanliness of insulators. The tightness of bolts and nuts in structural steel work and fittings shall be checked. If galvanizing of steelwork has been damaged anywhere, the part affected shall be properly protected by painting with cold galvanizing paint to the satisfaction of the railway. Muffing for each of the tower footings should be checked to make sure that it extends from well below the ground level to at least 380 mm above the ground in irrigated fields, 230 mm above ground level in dry location and 150 mm above the maximum water level in water-logged areas. Joints in transmission line conductors shall be not less than 15 m from the tower. There shall be no joints in tension lengths of less than 3 spans, nor any in spans over rivers, railway tracks or roads. A few jumper connections between line conductors shall be opened at random to check whether the contact surfaces are good and joint compound has been applied. At the same time, the tightness of all PG clamps should be checked. 20922 Clearances and Sag The minimum clearances shall be in accordance with 1. E. Rules and Indian Standards. In case of 132 kV lines under maximum temperature condition, in still air, the minimum clearances are indicated below. 1.Open route 6.1m 2. At all roads and accessible places 6.1m 3. Between nearest live conductor and any part of 4.6m any fences, wall, building or other structure on which a man may stand, or against which a ladder may be placed. 4. Between the nearest live conductor and the Earth. 6.1m 5. Between the nearest live conductor 6.1m and any tree or hedge in the vicinity. INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 182 6. Minimum spacing between conductors Vertical 3.9 m Horizontal 6.8 m The minimum clearance between live parts and earthed tower or cross arm members for 132 KV shall be 1. Single Suspension strings 1370mm in still air and when deflected by wind by 30 degree from the vertical. 2. Single Suspension strings 1070mm in still air and when deflected by wind by 60 degree from the vertical. 3. Strain strings at strain towers 1530mm 4. Jumper connections at strain towers when 1530mm deflected by wind upto 10 degree from the vertical. The height of the lowest part of conductor shall be checked and recorded - 1.At mid-spans at typical locations on the open route. 2. Above railway tracks, roads building and public places Minimum clearance of live parts shall be checked for each of tower at typical locations and recorded. Sag of the earth wires and conductors shall also be checked at selected spans and recorded. 20923 Earthing Every tower is individually earthed by connecting one of its legs to one or more earth electrodes near by, through a galvanized steel flat 40 mm x 6 mm so that the earth resistance is not more than 10 Ohm before the overhead earth conductor is bonded to the structure. Examine whether the steel flat is properly bolted to the stub-angle iron and well protected below the ground up to the earth electrode. 20924 Insulators and Insulation Resistance Suspension and strain insulators shall be in inspected as closely as possible for any chippings or cracks, for cleanliness, and preface of arcing horns at the line end of each suspension string above the conductor, at both ends of each tension string, and at both ends of each insulator string up to a distance of 1.6 km from the sub- station. The number of 255 mrn dia porcelain discs shall normally be 9 for suspension strings and 10 for tension strings for 132 kV supply. To provide graded insulation, the number of discs will be reduced by one, namely 8 for suspension string and 9 for tension strings upto a distance of 1.6 km from the sub-station. Duplicate suspension/tension strings shall be provided for all road crossings. For railway crossings, anchor type towers shall be provided on the two sides with duplicate tension insulators, the whole crossing, being in conformity with the ‘Regulations for Power Line Crossing of Railway Tracks’ ( Appendix iv) Insulation resistance for each power conductor shall be measured and recorded from sub-station to sub-station, using a 2500 V or 5000 V megger. It shall be not less than 100 Meg Ohm. INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 20925 Continuity Test Continuity of each conductor shall be measured from, substation. To substation using a megger continuity tester and the results recorded.- 20926 Accessories During detailed inspection, it should be verified whether every tower is fitted with an: anticlimbing device and enamelled number plates. In addition circular enamelled discs coloured red ,'yellow and blue are to be provided. on terminal towers to indicate the phases. Danger boards should also exist on the transmission line towers where they are near roads or other public places. ' 20927 General lnspection and Energization After defects noticed during detailed inspection are rectified, Sr. DEE/DEE(TrD) of the open line together with his counterpart on the construction organization and Contractors' representative shall carry out general Inspection to make sure that the lnstallation,is in good order. During this inspection, the inspection party will carry out as many spot checks as possible to confirm that the detailed inspection has been properly carried out earlier. On the basis of their personal observations, a joint certificate will be issued by the inspecting officers and contractors' representative, confirming that the installation is fit in every respect for energization Wide publicity should be given to warn the public that the lines will be energized and of the accompanying danger to any trespassers. After getting sanctioned of the CEE and Electrical Inspector to the Railway, and clearance certificate from all concerned in a manner similar to the procedure for energizing OHE described in chapter X, the transmission line may be energized provided the sub-station and the connected protective gear have already been tested and commissioned 20928 25 kV Feeders Detailed and general inspection of 25 kV feeder lines should be carried out on the same lines as described for the transmission lines and the OHE. Here too, each tower is individually earthed by a separate electrode, in addition to being connected together through the overhead earthing conductor. The, clearances to, road and rail crossings should be checked with respect to approved plans, duplicate insulators being provided in each case. No earthed structure, other than the earthed supporting structure of the 25 kV feeder lines shall be nearest than 2 m from the live OHE. Tower footing resistance, insulation resistance of both phase and return conductors and through continuity should all be checked and recorded. If the substation is already energized, the 25 kV feeder; lines can also be energized on lines similar to procedure described for the transmission lines and the OHE after taking all precautions for safety of equipment and staff working on contiguous sections. 111. PROTECTIVE EQUIPMIENT 20929 Testing of Protective Relays Before any traction installation is commissioned, the proper operating of every protective- relay should be ensured so that it can be fully dependent upon in all circumstances. This is done in three stages – -Checking the relay in the laboratory prior to installation. -Checking after installation and before the substation is commissioned. -Confirmatory test after energization and before introduction of commercial services. In carrying out the tests, the Manufacturers' instruction manuals should be studied. The commissioning engineer should be well acquainted with the principles of operation, constructional features and the traction load conditions, INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 184 so that the relays may be correctly set. 20930 inspection of Setting of Relays and Calibration of Meters Protective relays are usually received well packed in separate cases. -After opening the case, the relay should be- carefully removed, examined for any external damage and taken into the Relay Testing Laboratory. Before removing the cover, remove all traces of dust from the case and the cover. Check the name-plate particulars to see if they are correct. Check carefully the delicate relay movement and make sure if it is quite free mechanically, and all parts are clean and connections tight, taking care not to disturb the settings. See whether the flag operating and reset mechanism is functioning well. Examine the cleanliness and wipe of contacts. The performance of the relay for different settings should then be checked using standard relay testing equipment, making such adjustments as may be found necessary. A detailed record of the test set up and the calibration curves should be entered in a register as a permanent record. The plug 1 settings are then correctly made to cater for the expected load conditions. Where relays have both current and potential coils, as in directional and MHO relays particular check should be made to see whether the internal connections of the two sets of coils are correct. If the polarity of one with respect to the other is not right, the relay will fail to operate on a fault, which should, of course, never be permitted to occur. If everything is alright, the relay cover may he put back, after checking the interior once again and wiping all dust on the cover. It is recommended that the date of calibration should be painted on the case for ready reference. A test certificate should be issued to the field officer for record. Simultaneously, maximum demand and energy meters should also he got calibrated and sealed in consultation with the Supply Authority. 20931 Protective Devices at Sub-stations The following protective and indicating devices are provided for each traction transformer : 1.Differential protection 2.Restricted earth fault protection on EHV and 25 kV sides. 3.Buchholz relay with alarm and trip contacts. 4. Winding temperature protection with alarm and trip contacts. 5.Oil temperature protection with alarm and trip contacts. 6. Protection against low oil level. In addition, a low oil level indicator is provided on the conservator tank. Local Indicators are provided on the transformer tank for excessive oil and winding temperatures, whereas a common indication only is provided on the control panel at the RCC for excessive winding and oil temperatures as well as Buchholz relay. The following further protective relays are provided for each feeder circuit breakers : 1. Over-current relay for faults close to the substation 2. MHO relay for distance protection. 3. MHO relay for wrong coupling between two substations. Proper functioning of each of these relays and the contact mechanism of each should be checked individually.At the same time, the correct operation of the following annunciations and the associated cancelling buttons and flag indications should also be checked : 1.EHV transformer circuit breaker auto-trip. 2. Buchholz alarm INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 185 3. Buchholz trip 4. Winding temperature alarm 5. Winding temperature trip 6 Oil temperature alarm 7 Oil temperature trip 8 Low oil trip 9 25 KV transformer circuit breaker trip. 10., 25 kV feeder circuit breaker trip 11 Transformer circuit breaker inter-trip 12. 230 V ac failure 13 110 V dc low voltage 14 24 V dc low voltage d Check should be made of all indicating instruments on the control panel to see if the movements are free and the readings are correct. Test plugs where provided for checking relay operation should be examined if they fit properly. Indicating lamps should be functioning properly, but a switch should be provided to cut them out when the station is unattended. Check should also be made for proper functioning of device provided for tripping CBs in the event of 110 V dc supply failure. 20932 Control Circuits and Wiring After installation of all equipment and completion of control cable connections, a detailed check of the wiring should be conducted. verifying the colour, code and identification tags and markings on the terminal strips on the equipment and the control panels with respect to the approved wiring diagram. Insulation and continuity tests should also be taken and values recorded. A word of caution is necessary here. The detailed diagrams of control circuit and wiring, of control panel supplied by the Manufacturers should not merely be taken on trust, but subjected to careful scrutiny as to their correctness. Errors do occur in drawings and if they are not detected at the very early stage Itself, they may cause a great deal of confusion and trouble later. The best method of detecting errors in detailed wiring diagram is to prepare a simplified schematic or functional diagram so that the circuit arrangements becomes quite clear and obvious. It will then be known what exactly to do for any test, what links to close or open and what connections to make or break. To restore the connections back to normal after the tests have been successfully completed, a detailed diary should be kept of every change or alteration made for purpose of test. If any modifications are required to correct the errors discovered, the Manufacturer should be advised immediately and his confirmation obtained. When the work is completed, overall operation may be checked by manually closing the relay contacts and finding out whether the appropriate device has operated or not.. 20933 Fuses Control circuit fuses shall be-of correct rating. If the-trip battery circuit fuse is under-rated, it is liable to deteriorate due to excessive heating and fail ultimately, which could indeed be dangerous. To guard against this possibility, alarms are sometimes provided to draw the attention of the operator in the event of fuse failure. In ac traction, failure of battery fuse is automatically relayed to the RCC but the TPC cannot replace the fuse by RC, someone has to go and replace it which may take considerable time. In view of this, fuses in the control circuit may err by being slightly over-sized. but should never be under-sized. For the same reason all connections in the trip circuit should be well made and the fixing screws kept tight, but not over-tight which may cause excessive pinching of the connecting lead and may eventually cause a breakage. 20934 Insulation and Lead Burden Measurement Insulation resistance to earth should be measured. Any connection to earth and wiring made deliberately such as earthing links on current and voltage transformers and on dc supply should be removed before the test; care being INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 186 ‘A' should be a moving coil centre –zero type low range ammeter. A 6 V storage battery may be used to energized the primary winding through a single pole push-button switch. On closing the push button, the dc ammeter should show a positive flick, and on opening a negative flick. 20936 Primary Injection Test This check is carried out with a “ primary injection set” , which is usually arrange for connection to the 240 V supply means and furnishes heavy current at a low voltage. Provision usually exists to connect the secondary windings of the test set either in series or in parallel to get the necessary output. A 10 KVA test set usually permits currents up to 1000 A to be obtained with four secondary windings in parallel and upto 250 A at a higher voltage with the windings in series. When dealing with very large currents, it is essential that the connecting leads and area of contact and contact pressure should be adequate enough: otherwise, higher values of current will not flow. The merit of primary injection test is that it gives an overall check on the correctness of the entire circuitry. 20937 Voltage Transformer Ratio and Polarity Check Polarity of the potential transformer could also be checked using the same method described for current transformer testing. In this case, however, care should be taken to connect the battery supply to the primary winding with the moving coil ammeter connected to the secondary winding. The ratio check can be may when the 25 KV busbars are first made alive. The PT secondary voltage is then compared with that of another PT known to have the correct ratio, after connecting it to the primary bars. 20938 Electrical Operation of Indicators and Associated Devices All shunt connected indicator, annunciators, internal auxiliary elements, DC auxiliary and master trip relays, should be checked for operation at the minimum voltage stipulated by the Manufacturer. Series-operated indicators or auxiliary relays should be checked at their pick-up values. Confirm that auxiliary relays reset when voltage and current supply is removed after operation. 20939 Secondary Injection Test These tests are done with a secondary injection test set. Normally, operating times and minimum closing values are checked for induction relays. For instantaneous attracted armature type relays, the minimum closing and resetting values are checked. For directional relays, directional characteristics are checked. 20940 Alarm and Trip Check Ensure that all fuses, links, trip latches etc. are in normal position. By operating each relays manually, verified if the appropriate circuit breaker trips. Inter-tripping of primary and secondary circuit breakers should also be checked. There should be no normal-operation of any other circuit. In every case of tripping, the appropriate flag indication should take place on annunciator, accompanied by operation of the alarm. 20941 Load Test After the section is commissioned, a final check should be made of the proper operation of all voltmeters ammeteres and relays when normal load currents are flowing through the circuits. For differential circuits, spill currents should be measured to prove that protection will be stable under external faults, by shorting the secondary terminal on one, current,transformer : operation under an internal fault should also be checked The directional features of directional relays should also, be checked This ensures that the,relative polarity of CT and PT is correct. 20942 Confirmatory test of OHE Protective Relays A short time after OHE has been successfully charged at 25 kV, it is de-energized to conduct final confirmatory test on the operation of OHE protective relays. Although relays would necessarily have been tested on the test INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 188 bench at the laboratory and subsequently in the field after erection, a final confirmatory field test is essential before declaring the section as fit for commercial operation to ensure that in the event of a fault the relays do trip. 2. The over current and MHO relays should all be set for instantaneous operation as mentioned earlier. In all, the following three tests are necessary and in each case all the feeder circuit breakers and their associated relays should be tested one after another : a) A direct fault on the busbars of the feeding post to test operation of the over-current relays. b) A fault at the farthest end of a single line section under emergency feed conditions to check the operation of the MHO relay and also the under-voltage relay at the sectioning post. C) Closing the bridging interruptor at sectioning post to check the operation of wrong phase coupling relay. 3. Test (a) can be conducted as soon as the substation and feeding posts are commissioned, without waiting for the energization of the OHE. In carrying out Tests (b) and (c) one must provide and be prepared for the very remote contingency of the MHO relay failing to trip the circuit breaker when It is closed on the fault, due to polarity of the potential coil of the MHO relay not being correct in relation to that of the current coil. Before starting the test, trip circuit operation should be checked by manual closing of the relay contacts. A responsible official should remove the MHO relay cover and be ready to close the relay contacts manually and trip the circuit breaker, should it fall to do so automatically when the circuit breaker Is closed on the fault. Should this happen, the connecting leads either of the potential coil or the current coil on the MHO relay should be reversed and the test repeated. 4. For carrying out the short circuit tests, care should be taken to earth the line by a solid flexible, jumper connection (105 mm to an earthed structure. A thin wire such as 14 SWG should never be used for connection to earth, under the mistaken impression that the fuse would blow out and not jeopardize system stability, should the 25 kV circuit breaker fail to trip. It should be remembered that the circuit breaker is designed to clear the fault whereas the improvised fuse is not. When it blows on account of heavy short circuit current, the flash over caused by it can damage the galvanizing of the mast and perhaps shatter any insulator nearby. 5. A point to be- ensured in particular is that none of the relays at the grid substation trips during any of these short circuit tests. This can be ensured earlier by proper co-ordination of relay settings at the traction sub-station. Normally, the traction circuit breaker trips out within about 250 milli-seconds from the occurrence of short circuit. The Supply Authorities should be requested to set their relays allowing a time lag of 0.5 seconds to ensure that the substation circuit breaker dots not trip for faults on the railway traction system. 6. It is quite possible that in these short circuit tests, more than one relay associated with the feeder circuit breaker may operate; for example, the MHO relay In addition to the over-current relay, even for a fault close to the sub- station. This is quite in order, since this automatically gives back up protection. A note should be made as to which flag indications have operated to ascertain which of the protective relays have operated during each test. 7. When testing the wrong phase coupling relay, it may sometimes happen that the relay at one substation alone may operate and not at both ends, as may be expected. This is possible if the operating times of the two relays differ even slightly. This, however, does not matter at all. Nevertheless if it is required to check the other relay, the relay which has operated may be blocked and the performance of the other relay tested by a second test. 8. The operation of the under-voltage relay at the sectioning post for a fault at the farthest end under emergency feed conditions can be checked by posting someone at the sectioning post. The test could however be postponed by a few days and conducted after introduction of commercial services. 9. Since these confirmatory tests are to be conducted after successful energization of the OHE and before introduction of commercial operation, It is essential to complete the tests in the shortest possible time. However, being the most severe tests these should not be repeated too often. This can be ensured by organizing the work properly by posting testing parties at the right places and controlling all operations through the TPC and by RC. INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 IV. SWITCHING STATIONS AND BOOSTER TRANSFORMER STATIONS 20943 Power Supply Power supply for all switching stations is arranged through the 10 KVA,25 Kv/240V auxiliary transformers connected to UP and DN line in double line section. If an ac 240 V supply near by is available from the supply authority, a service connection should be taken from the source as well. A 24 hour record of voltage should be taken and the tap switch of the auxiliary transformers correctly set. 20944 Installation of Equipment The installation of every item of equipment like interruptors, isolators, busbars, lightning arresters and wiring from equipment to the control panel in the switching stations cubicle, 72/110 V and 24 V batteries and ,battery chargers etc..should be,checked, keeping the points referred to in paras 20915 to 20918 in mind, except for the following minor variations. 1. Intterruptors are installed for controlling supplies to the sub-sectors. The remarks made under para 20908 are equally applicable, except that no relays are associated with them. 2. Potential transformers for catenary supply indication are mounted on the switching station gantry. 3. 25 kV lightning arrestors are also installed on the gantry. 20945 Clearances Check whether the following minimum clearances for 25 kV do exist: 1. Height of any live conductors from ground level 3m 2. Distance between any live part(25kV) and 500m earthed part or part likely to be earthed (In special circumstances and with the approval of the design office this can be 450mm.) 3. Between any live part (3kV) and earthed part 150mm such as return conductor or return feeder No live part may project beyond the fenced enclosure except at a height of 6.1m or more. This should be particularly checked to guard against the possibility of danger to any member of the public who may walk by the side of the switching station with an umbrella or a long pole. Check and ensure that the distance from the centre of the nearest track to the face of the switching station gantry is not less than 3.5 m. 20946 Auxiliary Transformers & Booster Transformers These should be inspected and tested in accordance with the procedure earlier stipulated under “substation” –part I above. The mounting of these transformers should be checked to ensure proper fitment and conformity with schedule of dimensions and electrical clearances. The booster installations, in particular should be checked for correct jumper connections. INDIAN RAILWAYS - AC TRACTIOP4 MANUAL - VOLUME 11 PART 20947 General Verify whether the erection of fencing is neat and all parts are given a good finish with paint, the gate is provided with a good lock and anti-climbing devices are satisfactory. The area inside the switching station should be leveled at least 10 cm above the surrounding area. Good drainage must be provided so that there may be no possibility of water logging at any time. To facilitate unloading and loading of heavy materials transported by trolley or OHE inspection car, a suitable loading platform should be provided from which a path-way should be available upto, the gate. Wherever possible a jeepable road approach should also be provided from the nearest public road. When the switching station is at the foot of or at the top of a steep embankment, suitable foot steps should be provided leading upto the gate. 20948 Interlocking Verify whether the double-pole isolator associated with every interruptor is equipped with an interlock and it is functioning properly. It should not be possible to open or close the isolator unless the interruptor is locked in the open position. It should also not be possible to operate the interruptor either manually or by RC, unless the isolator is locked in the open or closed position. To ensure this, the interlocking device should consist of a lock combined with an electrical contactor on the operating mechanism of the interruptor to make or break the RC circuit and a lock for the isolator operating mechanism, with a common captive interlock key for the two locks. 20949 Feeding Posts At locations where the traction substation is close to the tracks, the feeding post may be a part of the substation; if, however, it is far away, the feeding post close to the tracks will receive 25 kV supply from the traction substation, with 25 kV feeder circuit breakers located at the substation end. In either case, the neutral conductor (also called the negative or return conductor) of the feeder line should be solidly connected to the track rails, In addition to being earthed at the traction transformer end. This connection to the rails is vitally important for the proper and safe working of the traction system and it should under no circumstances be broken. To ensure this, the neutral conductor is connected to the rails by eight independent galvanized steel stranded (7/16) cables for a double track section with two conductors for each rail. The ends of stranded cables are brazed or welded on to suitable shoes which are riveted to the rail webs. Examine all the connections and make sure that the cables are well bonded to the rails with sufficient length left free for flexibility. The down-lead from the terminal tower should be well protected mechanically to prevent its being cut and stolen. 20950 Number Plates and Boards Check the numbering of the interruptors, isolators, PTs and then jumper connections to the OHE to see if they do correspond to the numbering scheme on the control panel in the switching station equipment room, the mimic diagram board at the RCC and the sub-sector numbers. Check also if the following boards and fittings are provided at each switching station : 1 Switching station name board, 2."Danger boards" to caution public, 3. "Protected place" board prohibiting unauthorized entry, 4. Fire-buckets and fire extinguisher inside the equipment room. INDIAN RAILWAYS - AC TRACTION MANUAL VOLUME 11 PART 1 5. First aid box and “Rules for Resuscitation from Electric Shock” board inside the equipment room. Essential caution boards and number plates should be painted with fluorescent paint so as to be brightly visible in light at night. 20951 Earthing and Bonding The structural steel work as well as the neutral conductor of auxiliary transformer, and the metal case of every electrical equipment shall be connected by two independent connection to earth in accordance with the “ Code for Earthing Traction Power Supply Installation” vide Appendix III. According to this code, HT and LT earths should be provided separately, but interconnected together by a link. It is equally important to check that the structure supporting the busbars are solidly connected by two independent connections to the none- track circuited rail with single rail track circuit or to the mid point of the impedance bonds where both rails are used for track circuiting. During detailed inspection, the resistance of each electrode should be measured and recorded by a megger earth tester so that the combined resistance of the HT earthing system is 2 Ohm, or less and of the LT earth 10 Ohm or less, when not connected to the rails. V. REMOTE CONTROL EQUIPMENT 20952 Importance of Remote Control Remote Control Center is the nerve center of the traction system, from where full control over every switching operation on the entire electrified route is exercised, its efficient operation is, therefore, of prime importance for successful working of the system. It is desirable to complete all tests and trials on the RC equipment at the RCC and at the switching stations and to make them fully functional before energization of OHE. To achieve this, tests and trials should start about a month earlier, by which time the following item of work should be ready. 1. Derivative cables from the main telecommunication trunk cable should be led and terminated inside the equipment room in RCC, substations and each of the switching stations. Care should be taken to ensure that the metal sheathing of the derivative cable is terminated short of the cable terminating box and kept insulated from earth inside the equipment room and surge arrestors are provided for each terminal. 2. Repeater stations should be fully functioning. 3. All control phones in RCC and TPC telephones in sub-stations and switching stations be installed and commissioned. 4. The air conditioning of the RCC should be complete before the erection of the RC equipment starts. 5. RC equipment should be ready and wired up at RCC control led posts. 6. Batteries and battery charger along with power supply and charging arrangements should be ready. 20953 Manning of Substations and switching posts When RC equipment is first brought into operation, it will take about 6 months before teething troubles are overcome and equipment stabilizes for trouble free service. During this time, it is necessary to man the substations and switching stations to operate the interruptors manually and give reports to TPC when required. This situation also arises for longer period if the RCC is not ready before energization. The switching station attendants should be given adequate training in their duties and should normally be available from about a month before the date of commissioning. It is usually possible to introduce commercial service on limited scale, before commissioning of RC equipment. INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 20954 Level Measurements Signal levels should be measured and recorded both at the sending and receiving ends at the control center as well as at every substation and switching station. These measurements are of two kinds: 1. Individual levels of every frequency on the 'send' channel. These are measured by a vacuum- tube voltmeter (VTVM) /Transistorized voltmeter (TVM with its selector switch in "high" Impedance position at the oscillator output terminals. These should be about - 16 dB. 2. On the receive side, the levels are taken with VTVM in the "high" - impedance position, at the detector Input terminals: this should be between-17 and - 25 dBm. 1 3. Composite levels taken between the terminals of the tele-command and tele-signal cable pairs with a VT VM with selector,switch in the "high" impedance position. Readings may also be taken at the input and output terminals of the repeater station and plotted. on a graph sheet. 4. Measurements should be taken of the levels of every channel on send and receive pairs at the control centre using the Selective Level Meter. The levels for the send-channels should not be lower than - 22 dBm. and for the receive channels - 22 to - 30 dBm. 5. After final adjustment of the levels, a note should be made of the values of the attenuation pads included in all the circuits and kept as a permanent record for purposes of comparison and reference. It may be noted that the line impedance of the send and receive circuits is 1120 Ohm whereas that of the amplifier output only 150 Ohm. A matching transformer is therefore provided between the two. When measurements are taken, care is required to keep the selector switch of the VTVM in the "high" position, as long as the circuits are through, but if the output level is to be me asured with the line or equipment disconnected the switch shall be kept at the 150 Ohm or 1120 Ohm position as necessary to achieve matching. Another point to be kept in mind is that although the individual level of a single channel is say -22 dBm, the level indicated on the line is much higher if measured with VTVM because of the presence of a large number of frequencies each of which has a level of - 22 dBm. Thus the correct reading of - 22 dBm is indicated when a Selective Level Meter is used with frequency range switch in the "frequency" position; but the same meter would indicate perhaps + 5 dBm if there are say 12 channels and the frequency range switch is kept In the "flat" position. Distinction should therefore be made between the individual channel levels and composite level, where all frequencies are present. 20955 Detailed Inspection of RC Equipment Detailed program of erection of equipment, sequence of preliminary tests to be carried out at the RCC and controlled stations, shall be furnished by the contractor to enable the Railway staff to carry out stage Inspections and testing of individual panels, equipment cabinets and control units at the master station and Remote Terminal units. When contractor reports completion of erection, commissioning and all adjustments and testing work and notifies that the installations are ready, detailed inspection shall be carried out by AEE (TRD) and open line staff along with their counterparts on construction organization and representative of the contractor. The defects noticed shall be rectified immediately. Contractor shall also furnish a detailed test program for the final testing of the RC equipment for the approval of the Railway Engineers. These tests will he done jointly by open line officers, RE officers and the contractors' representative. The test program shall cover the proving tests for all the parameters and facilities provided for the operation of RC equipment In the specification. The tests at site after Installation and commissioning shall constitute the acceptance tests, which will be carried out after the detailed Inspection and rectification of defects is completed. Thorough checking of all switching operations, correct operation of all alarm, Indications and annunciation facilities, tele- signallng and tele-metering arrangements, mimic diagram displays, VDU displays, INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART data –logging and data storage, diagnostic facilities etc. shall be done from both control stands of the master station as well as from the remote terminal units. Operating time for various operation shall also be checked and recorded. All these tests carried out jointly shall be recorded so as to establish, authentic initial record of the performance of the equipment to ensure that the RC equipment is complete and trouble free. 20956 Interlocking of the Bridging Interruptor Interlocks in the RC equipment for the bridging interruptor at the sectioning post provide for the following: 1. When catenary supply is available on both sides of the interruptor, the interruptor should not close. 2. When supply is available only on one side, the interruptor can be closed. 3. When supply is not available on both sides of the interruptor the interruptor can be closed but should trip immediately This is achieved by utilizing 100 or 110 V ac supply from potential transformers provided for this purpose at the sectioning post. Provision is also made for the bridging interruptor to trip if the catenary voltage drops too low. This sectioning is adjustable between 15kV and 19kV and should be set at 19kV. The above interlocks should be throughly checked when commissioning RC equipment at sectioning posts. 20957 General Inspection by Divisional Officers After defects noticed during the detailed inspection as above have been rectified, the Sr.DEE/DEE(TrD) of the open line together with the counterpart on the construction organization and Contractors representative’s shall carry out general inspection of the entire installation to make sure that it is in good working condition. During the inspection verification of as many tele-command and tele-signals operations as possible shall be carried out from the control centre. Inspection of the installation at every sub-station as many posts as possible shall also be carried out. Level and frequency measurements should be taken at random at a few points to compare the result obtain with those recorded during the detailed inspection. The divisional officers will issue a joint certificate if they are fully satisfied with their observations and tests, that the RC installations are fully fit for commissioning. Thereaftaer, the RC may be put into regular services and its operation closely watched by manning the switching stations and sub- stations as mentioned earlier. Detailed record of every failure shall be maintained by TPC and the maintenance official. Each of these failure should be gone into fully to ascertain the cause of failure, which incidentally would give the staff excellent opportunity to get familiar with the circuitry and fault- find in a procedure. VI. OVERHEAD EQUIPMENT 20958 Detailed Joint Inspection of OHE The importance of OHE arises from the fact that it is extensive, with a very large number of insulators, fittings and component parts, failure of any one of which may result in dislocation of traction services for appreciable periods untill the defect is rectified. The adjustment work is particularly important at cross-over and over-lap spans since any wide departures from the standards laid down could cause entanglement of the pantograph with the OHE, with serious repercussions. The need for a very thorough detailed inspection of every part of the installation, post by post, can not, therefore, be over-stragged. When the OHE contractor reports completion of all adjustment work, detailed inspection will be carried out by the AEE(TrD) and staff of the open line with their counterparts on the construction organization and INDIAN RAILWAYS - AC TRACTION MANUAL VOLUME 11 PART 1 representatives of the Contractor, using on OHE inspection car, flat-topped wagon of wiring train, or ladders as may be convenient. 20959 Compliance with Latest The OHE shall be strictly in compliance with the latest approved General Supply Diagram, Sectioning Diagram, Layout Plan and Structure Erection, particularly in regard to 1. run of conductors; stagger and height; 2. disposition of brackets and clearances; 3. correctness of jumper connections, especially at switching and booster transformer stations; 4. numbering of interruptors, circuit breakers and isolators in relation to the elementary sections, sub- sectors or sectors controlled. 20960 Infringements None of the wayside or over-line structures shall cause infringement of the Schedule of Dimensions. Every such infringement shall be individually recorded and action taken immediately either to have them removed or, where this Is not possible, to obtain sanction from the Commissioner of Railway Safety. 20961 Important Point to he Checked The following points shall be checked during the detailed inspection: 1. Cantilever Assemblies: Every cantilever assembly shall be adjusted strictly in accordance with the approved structure erection , especially in regard to the positioning of stay arm, bracket tube and register arm. The projection of bracket tube and register arm and the allowance in the stay arm shall be sufficient for slewing of tracks. Normally this allowance is 15 cm to 20 cm from the centre line of catenary suspension bracket to end of bracket tube and 20 cm (min.) for register arms. All nuts should be tightened and locking plates provided with split pins or check nuts. Make sure that all temporary earths provided by Contractor's men during construction work have been removed. 2. Anchoring Points: The movement of counter-weights shall be free and not obstructed in any way. Flexible steel ropes shall move freely and centrally with respect to the pulley sheaves and not rub against any member. The distance between the pulley centres and the height of counterweight above the muff level, shall be as per the chart in relation to the prevailing ambient temperature. Anti- creeps shall be properly tensioned and positioned. 3. Overlap Spans.. Adjustments at insulated and uninsulated overlap spans, turn-outs, crossovers and section insulator assembly shall be correct not only in respect of the run of conductors and jumper connections, but also the height of contact wire. The separation between different OHE and displacement of cantilevers at insulated overlaps should be adequate. 4. Insulators : Insulators shall be perfectly clean. Should the surface be polluted by dust, it should be cleaned and gloss restored. All. insulators on out-of-run wires should be so located that they do not foul but are well away from the zone swept by the pantographs: The runners of section insulators should be so located as to be beyond the zone of sweep of pantographs running on adjacent tracks. There should be no undue sag due to the section insulators, the runners should be level and not be tilted to one side so that the pantograph may pass smoothly. 5. Height of Contact Wire: This shall be checked at every structure and at mid-span for regulated OHE. A pre- determined sag in the contact wire of 50 mm or 100 mm at mid-span on a 72 m span for 50 or 100 mm presag compensated OHE respectively should exist on the open routes. Height of contact wire at level crossings shall not be less than 5.50 m. INDIAN RAILWAYS - AC TRACTION MANUAL VOLUME 11 PART 1 195 6. Stagger : Stagger in tangent track shall be to the left and to the right of the alternatively, not exceeding 200 mm on either side of the centre line of the track, except where otherwise specified in Structure Erection Drawings. Stagger for in-running OHE shall not be more than 300 mm at the mast/structure on the outside of curves except in case of overlap spans and also at the turn-outs. Stagger of contact wire at mid- span in transition portion of the curves shall be within 200 mm. 7. Gradient of Contact Wire : On both side of overline structures, tunnels and level crossings, the gradient of contact wire shall be in accordance with the approved profile. 8. Clearances: The live metallic caps of insulators on out of run wires shall be at atleast 2 m away from adjacent earthed mast/structure (other than the OHE structure). The distance of these insulators shall be 3 m from the bracket supporting the OHE in case of insulated overlaps. Clearance of 2 m shall normally exist from nearest point of two adjacent elementary sections except at the section insulators. Where clearance of 2 m is not available. It shall be not less than the minimum long duration electric clearance of 320 mm. Whenever the OHEs of two elementary sections cross one another, necessary cut in insulators shall be provided. 9. Bonding : Every mast/structure supporting OHE as well as platform structures, foot over bridges etc. shall be properly bonded to the rails and earthed in accordance with the Bonding and Earthing code ( Appendix II) 10. Return Conductors of Booster Transformer Installations: The return conductor connection both at the OHE and the rail should be checked from the point of view of good electrical contact and security from mechanical damage. 11. Telephone or Power Crossings : Keep a close watch for any overhead telephone crossings over the OHE, which may not have been removed by oversight. Immediate steps should be taken to have these removed. High voltage transmission line crossings across the tracks shall be checked against the approved plan authorizing the crossing, particularly the clearance between the OHE and the guard wires, duly recording the results individually. If the crossing is not in accordance with the approved plan, the Supply Authority should be contacted immediately and the infringements should either be removed or necessary relaxation be obtained from CEE and Electrical Inspector to the Railway. 20962 Notices to be Displayed – Caution Boards and Number Plates During the detailed inspection, special attention shall be paid to verify whether the following notices have actually been displayed at the various locations indicated below: - 1. ‘Treatment for electric shock’ boards, giving instructions for treatment of electric shock in English and the regional language, at all railway stations (ASMs or SMs Offices) signalling cabins, PWIs Sub-PWIs and IOWs offices and depots, Signal Inspectors’ Officers and depots. OHE Maintenance depots, OHE inspection car sheds, substations, switching station cubicles, loco sheds etc. It should be noted that standard printed charts for ‘Treatment for electric shock’ are meant for voltages upto 1100 Volts. A person in contact with higher voltages should be isolated only after ‘switching off power’. 2 General ‘Caution Notices’ regarding danger of high voltage traction wires for public at various entrances to railway station and for staff at prominent places at each station, particularly on stanchions or pillars supporting platform roof. 3. “25 Kv Cautions Boards” shall affixed on to the screens erected on foot over and road over bridges. 4. ‘Danger’ boards on level crossing height gauges. 5. ‘Engine Stop’ boards, at termination of OHE in the sections to be energized. INDIAN RAILWAYS – AC TRACTION MANUAL –VOLUME II PART I 196 6"Caution-Unwired Turn out" boards ahead of all unwired turn-outs or crossovers taking off from wired tracks. 7."Warning" boards for neutral sections. 8.Boards for "Switching on" and "Switching off" of power at neutral sections. Four boards are required for each track as detailed in Chapter 11, Vol. 1. 9."Danger" boards to be installed on OHE near watering stations, if any. 10."25 kV Caution" boards at sub-stations and switching stations. 11."Caution" notices on all diesel, electric and steam locos which work on the energized section, including those owned by private parties. 12."Caution" boards at such signal posts where protective screening cannot be provided for signal and telecommunication staff. 20963 Recording of Defects and Rectifications During the detailed inspection, defects and deficiency lists as indicated in para 20903 shall be jointly prepared. As soon as the defects are rectified, the open line officers should be advised and suitable remarks made against each Item of the list. The open line officer and his staff, if deemed necessary, re-cheek the Installation, to ensure rectification of defects. - 20964 General Inspection of the OHE by Divisional Officers After all major defects observed during detailed inspection have been rectified 'Sr' DEE/DEE (TrD) of the open line and Dy. CEE(OHE) of the construction organization shall carry out a 11 General Inspection" of the entire section proposed for energization, along with the Contractor's representative. For this purpose, an OHE inspection car fitted with pantograph shall be used and run at a speed not exceeding 8 km/h observing all safety precautions laid down, such as earthing the OHE. The pantograph may be used to measure height and stagger of contact wire, which should be test checked at least at two locations per track km. The object of this "General Inspection" Is to make sure that the OHE and connected installations are in good order and are fit for energization. During this inspection, the whole installation shall be inspected visually observing, in particular, the following details and looking for any thing unusual or abnormal in the installation : 1. Cantilever assemblies, positioning of fittings, stagger of contact wire, lift of the steady arm in curves where the radial pull of contact wire tends to move the steady arm upwards, kinks or twists in contact wire, infringement of section insulators and conductors in overlap spans or any deformity suffered anywhere. Any loose wires hanging anywhere or other obstructions shall be observed, and any abnormality removed or rectified immediately. 2. Clearances to live metal parts of insulators on out-of-run wires should be atleast 2 m from the adjacent structures (other than OHE). During this inspection, spot checks shall be conducted at as many places as possible to verify whether the detailed inspection by the senior subordinates has been thorough, to confirm that the defects noticed earlier have been rectified and to make sure that the installations are in excellent order and suitable, for energization subject to final pre-comrnissioning tests. 20965 Lapping and Polishing of OHE After the OHE is ready in all respect, lapping and polishing of contact wire be undertaken to remove all dirt collected INDIAN RAILWAYS - AC TRACTION MANUAL VOLUME 11 PART 1 197 on the contact face with the pentograph. For this purposes an electric loco pentograph raised and hauled by a diesel loco may be use at a speed of 15 to 20kmp/h during the first run and not more than 40kmp/h in subsequent runs. Alternatively, an OHE inspection car may be used. It is an advantage if before lapping by pantograph under side of contact wire is manually cleaned by rubbing and wiping with a wet cloth and detergent and finally wipe with clean cloth. Normally 3 to 4 runs for lapping and polishing may be done. When lapping and polishing is in progress suitable safety precautions to block the section and earthing of the line as per rules, should be taken and work is supervised at a level not less than CTFO. 20966 Procedure for Final Test of OHE After the OHE is declared as fit for energization and all construction staff have been withdrawn from the field, insulation and continuity test shall be conducted jointly by officers of the construction organization and the open line with assistance of senior subordinates. This should be done at least a day in advance of energization. This tests should be conducted for every elementary section. The following preliminary action shall be taken to prepare the circuit for the test. To carry out the test in a systematic manner, a detailed programme of work should be prepare. A senior, experienced official should be nominated for controlling the movements of all working parties each of whom will be given a copy of the programme with specific instructions as to the sequence of switching operations to be carried out. This preliminary action should be taken atleast a week in advance of the date fixed for the test. On the day of test, interruptors and circuit breakers at all switching stations shall be taken on ‘local’ control and RC put out of operation. All interruptors and double-pole switches are then opened and locked in the open position’Danger-Men Working’ boards should be attached to the operating handle of each 25 kV isolator at feeding post. All potential and auxiliary transformers at switching stations should be temporarily disconnected from the busbars. All other isolating switches in the various yards and other locations provided for isolation of elementary section also be plays in the “off” position. When all these operation are completed a confirmatory message shall be sent to the TPC. The test shall be controlled by one senior official who shall continuously remain at the RCC and direct al operations as required. Basically, these tests comprise- 1. Measurement of insulation resistance of every elementary section with respect to earth. 2. Checking electrical independence and insulation resistance between adjacent elementary section and also adjacent sub-sectors. 3. Checking electrical continuity of every sub-sectors. The test shall be carried out by one party with the assistance of two or more field parties as required. The control party alone will carry with it all test instruments and take measurements. The field parties will merely carry out instructions given. They should have with them necessary jumper connection and earthing poles for earthing the equipment when directed to do so.The field parties are forbidden to carry out any operations on their own. As the different working parties will be working at different locations, independent from one another, they should carry with them portable telephones through which they will remain in continuous contact with TPC through emergency telephones circuit. In case the emergency telephone circuit is not available,alternative arrangements shall be made by S&T Department for telephone communication. Along with the control party carrying out the tests, the Contractors shall attach a work party who will accompany the control party from location to location and rectify any defects which may come to light during the tests. 20967 Insulation Tests Starting from the feeding post, the control party will measure and record the insulation resistance of every INDIAN RAILWAYS- AC TRACTION MANUAL – VOLUME II PART I 198 elementary section to earth by a 2500 V megger, after arranging with the out-field parties to (i) isolate the elementary section concerned and (I!) earth adjacent elementary sections. This test will show - 1. the insulation level of every elementary section; and 2. the electrical independence of the elementary section, from adjacent elementary sections. If the tests for all elementary sections at that location are satisfactory, the control party may proceed to the next elementary section and carry out similar tests. when all elementary sections at a particular station have been tested, the control party will move to the next station, directing the field parties to do likewise and carry out the tests on each elementary section at that station as before until every elementary section in the sector has been tested. During the course of construction work, erection staff usually provide temporary earths, using a short piece of binding wire on the OHE at certain locations to safeguard themselves, but after the work is completed these temporary earths may not have been removed by oversight. Such temporary earths on the OHE will give misleading readings during the final insulation test and cause annoyance. To prevent this, Contractors should be particularly instructed earlier to remove all such temporary earths. Guide Lines for Minimum Permissible Insualtion Resistance It Is very difficult to lay down any specific rules in regard to the minimum permissible values, as they depend upon a number of factors, which should he taken into account when fixing the value In any given case. Some of these factors are mentioned below. 1.. Voltage rating has an important bearing on the minimum value necessary, before switching on supply. Obviously, the higher the voltage rating, the greater should be the insulation resistance. 2. Condition of Equipment : The insulation resistance for new equipment should necessarily be much more than for the same equipment after a few years of service. Similarly, the value required (after an equipment has been overhauled, cleaned, dried out) before being turned out of the repair shop should be appropriately higher than when the same equipment was in service before being brought into the shops. A unit which is lying idle for some time may show a comparatively low megger reading merely because of absorption of moisture and yet its insulation may be good and it would work satisfactorily when put into service; the absorbed moisture would soon be driven out when it is loaded up and the insulation resistance would automatically improve. 3. Type of equipment : It is a fundamental fact that the larger the number of leakage paths, the lower would the insulation value tend to be. Assuming that the voltage rating and the type of insulation provided for two armatures are Identical it is obvious that the one with a commutator will have a lower value of insulation resistance, than one with mere slip rings. For the same reason, the insulation resistance of 25 kV OHE tends to be quite low, Assuming that each support Insulator has a value of 500 megohm, an elementary section may have 50 of them in parallel, bringing down the overall value to 10 meg ohms. Smoke pollution will greatly diminish this too. A single badly polluted section insulator may easily bring down the value to half a meg ohm or less. While one would not dream of switching on supply to a 3.3 kV transformer showing so low a reading- 25 kV supply is commonly switched on to the OHE even in such cases since the accumulated dust and smoke particles, which are responsible for the low value of resistance, soon get burnt out, and the insulation resistance usually improves greatly after energization.. Size of plant :Some of the formulae commonly used are Large AC motors : V ------------------------- at 75"C 1000 + (kW/100) INDIAN RAILWAYS,- AC.TRACTION MANUAL - VOLUME 11 PART 1 199 Large DC motors V ------------------------at 75 0 C 1000- + kW Having referred to the various factors which should be taken into account in fixing the minimum value of insulation resistance, a few thumb rules are given below for guidance: - Insulation resistance in megohoms to earth at room temperature (40 0 C) 1. Intenal wiring 50/number of outlets 2.Power equipment in general 2Meg/kV desirable 1Meg/kVminimum 3. Transformer windings 400V-2Meg,11kV-50Meg 25kV-200Meg.,132kV-2000Meg. 4. Circuit -Breakers -do- -do- 5. OHE-Elementary Section New installation -25Meg. desirable On sections having steam traction And several section insulators. -1Meg. (These, however, would need to be cleaned to improve IR) 6.Traction Motors 1 Meg. for motors upto 750 V and 3Meg for motors of higher voltage (at 75 0 C) 20968 Continuity Tests When insulation tests are completed for all the elementary sections, the control party may proceed in the reverse direction towards the feeding posts carrying out continuity tests as described below - In this test, the various control switches which might have been opened out earlier should be put back to their final positions as indicated in the Station Working Rules, as in normal operation. Any temporary earths provided for earthing adjacent sections shall be removed. When this is done, the various elementary sections are automatically joined up electrically and each sub-sector is made through' The continuity test is then conducted by a low reading ohm-meter by measuring the resistance of each sub-sector from the feeding post and with each sub-sector earthed at the farthest point towards the neutral section. The through continuity of every sub-sector shall be checked individually. It is important to note that a megger insulation tester is unsuitable for measuring continuity as It may read zero even when the resistance is as high as 1000 ohms. If the tests show up any defects on the line, -they should be rectified at once. Sometimes, it may be found that although the insulation resistance is all right, there is no through continuity on some sub- sectors. The most probable cause for this is a disconnected jumper connection at an overlap span. This should also be immediately traced and rectified. INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 1 20969 Divisional Officers' Joint Certificate The test results shall be recorded and signed by Sr. DEE Open line and Construction and forwarded to CEE, along- with other papers for sanctioning energization in his capacity as Electrical Inspector. VII. GENERAL ARRANGEMENTS 20970 Preparation for Operating Electrified Services While the engineers are busy carrying out tests and trials of electric equipment to get everything ready by the target date fixed for commissioning, several steps have to be taken by the Operating Department to be ready to operate the electrified services when the section is commissioned. The DOM of the open line and the DOM of the construction organization shall both be jointly responsible for the following : 1. The Rules and Regulations concerning operation, namely General and Subsidiary Rules, Revised Station Working Rules to come into operation after introduction of electric traction, relevant Chapters of this Manual shall be handed over to every Station Master on the section to be electrified. In addition It is essential that the Implications of these rules and procedures should not only be explained to the concerned staff, but they should be examined verbally to make sure that they do understand them and further, their assurance In writing to that effect should be obtained. The training of Station Masters, Section Controllers, Cabin staff and other categories in the special rules and procedures applicable to 25 kV traction is best arranged at a short orientation course for the purpose in the Zonal Training School. 2. (a) At every station on the electrified section, a large scale Sectioning Diagram, should be exhibited, with the different elementary sections painted in distinguishing colours to help better understanding, also showing location of isolating switches, wired and unwired lines etc. The meaning of these should be explained to the concerned staff. (b) A complete sectioning diagram of the OHE for the relevant section should also be exhibited in the office of the Section Controller in a similar manner. These diagram shall be kept up dated by OHE supervisors, marking the changes made from time to time. 3. Sufficient number of 'Yellow Warning Collars' should be supplied to each of the signal cabins; the cabin staff should be instructed regarding their purpose. They should also be told that no electric train or EMU should ever be permitted to enter an unwired line or a section for which power block has been taken. That they understand the new procedures should be confirmed by them in writing. 4. Station Masters and Section Controllers should also be fully conversant with the system of power blocks and the need for longitudinal and cross protection on electrified lines, and the precautions to be taken by them in regard to train movements especially oversize consignments. 5. Station Masters/ Assistant station master should be issued with competency certificates, after giving practical training, to enable them to operate specific isolators under instructions of TPC. 6, First Aid boxes and charts showing resuscitation of persons who have suffered electric shock should be kept at every station. As many persons as possible should be trained in the correct method of rendering artificial respiration, preferably by a doctor. 7. The extreme danger of any one coming near line OHE should be fully explained and widely publicized amongst all staff and members of the public. No one should be permitted to ride on roofs of coaches and locomotives. INDIAN RAILWAYS - AC TRACTION MANUAL - VOLUME 11 PART 8. The rules for watering of carriages should be distributed to all TXR and station staff concerned and the procedure fully explained and assurance obtained from them in writing. 9. On all steam and diesel engines which may enter the electrified section, 'Caution' legends shall be painted on the side panels. Steam engine Drivers and the Firemen should be particularly warned that they should under no circumstances climb up the coal stack on the tender or wield the long steel rake so as to come any where near the OHE and never direct jets of water on the coal in the tenders or towards the traction wires. Experience has shown that In spite of such warnings, many an unfortunate loco Driver or Fireman have suffered electrocution: by force of habit they climb up the coal heap for loco for some work, forgetting the presence of OHE in a newly electrified section. Drivers and Firemen should be repeatedly warned of the danger of death due to such carelessness. 10. Traffic staff should be advised of the provision of emergency telephone sockets and their locations, and instructed in the correct way of plugging in these telephones into the sockets. After the two DOMs have toured the area and assured themselves that all the above preparatory steps have been implemented, they shall render a certificate to the effect that the section can be opened for public carriage of passengers under electric traction without endangering the safety of the travelling public or of the employees of the railway. 20971 Preparation by the Engineering Department The Divisional Engineer of the open line and his counterpart on the construction organization shall also warn engineering staff In regard to the precautions to be taken by them while working on electrified sections. The PWIs and the maintenance gangs should be particularly advised that the alignment of the track with respect to the OHE structures should be strictly preserved and maintained. Their attention should be drawn to the instructions contained in Chapter 11 Part 'J' of IR Permanent Way Manual for taking the necessary steps to educate the Permanent Way staff and to equip them with the accessories. 20972 Preparation by the S&T Department Introduction of ac 25 kV traction involves a considerable amount of work to be done by the S&T Department, to modify the existing circuits, shifting of signals, introduction of colour light signals and laying of appreciable lengths of signal cables apart from providing telecommunication facilities required for electric traction. The precautions to be taken in testing and commissioning the S&T equipment, which should precede electrification, are the responsibility of the S&T Department and is, therefore, not dealt with here.

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