CH 19.pdf

Chapter 19: Outdoor Signalling - Installation, Testing and Maintenance of Equipment Section 1: General Instructions on Tools 19.1.1 (a) All staff engaged in the installation and maintenance of signalling equipment shall be in possession of rubber...

Chapter 19: Outdoor Signalling - Installation, Testing and Maintenance of Equipment Section 1: General Instructions on Tools 19.1.1 (a) All staff engaged in the installation and maintenance of signalling equipment shall be in possession of rubber gloves, proper tools pliers, screw drivers, etc. (b) While using metal tools like screwdrivers, nose pliers, cutting pliers, etc. near the working equipment, care shall be taken to avoid short circuiting and consequent blowing off of the fuse. Adequate number of insulated tools shall also be maintained. (c) A list of specific tools to be maintained, shall be circulated by PCSTE as per specific needs of zonal Railway. (d) A rubber floor mat shall be used for attending to circuits carrying more than 110 V. 19.1.2 Soldering Care (a) Staff working in the installation and maintenance of signalling equipment shall be conversant in use of soldering iron/gun for making good soldering joints. (b) Care shall be exercised to avoid dropping of particles of solder and clippings of wire on adjacent terminals and apparatus. (c) In addition to soldering irons of adequate wattage (65-125 W), for the type of work done, the following shall be at hand: (i) A small file for dressing the soldering tip (ii) A fire proof pad for wiping the tip (iii) A mica sheet of adequate size or a suitable stand for soldering iron (d) Electrical soldering irons shall be switched off when not in use over extended periods. (e) While making a soldering joint, the surface shall be thoroughly cleaned, fluxed and tinned. (f) Use of too much solder shall be avoided to prevent lumpy connection. (g) Soldering iron shall not be held on the wire connection for too long to avoid damage to insulation. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 387 of 530  (h) Imperfect joints are the result of any one of the following causes, which should be avoided: (i) Soldering iron not sufficiently hot. (ii) Soldering iron held on the connection for insufficient length of time. (iii) Unclean terminal or wire. (iv) A solder of improper composition or inferior fluxing agent. (i) A newly soldered connection shall not be disturbed till the solder has thoroughly cooled. (j) Railway to conduct the periodical training on proper practices for soldering, in-house or through outside agencies. 19.1.3 Wire Termination (a) While terminating wires, care shall be taken to bend the wires in clockwise direction. (b) Wire strippers shall be used for the purpose of stripping off the wire insulation. Cutting pliers shall not be used for the purpose. (c) Washers and check nuts shall be used whilst fastening. (d) Not more than two wires shall be terminated on one terminal. (e) Multi-strand wires shall be terminated on terminal lugs and covered with insulation sleeves. (f) Wires of cable shall be neatly terminated and properly bunched. (g) Crimping tools of appropriate design should be used and whenever lugs are crimped, proper soldering should also be ensured. Section 2: Installation of Signals 19.2.1 Colour Light Signals Installation (a) Colour Light Signals shall be multi-unit (approved type) and be provided with LED lamps (approved type). (b) Location of Signal: The location and spacing of signals shall be in accordance with codal provisions & approved plans. The signal shall be so located to extend a clear view to the Loco pilot of an approaching train and is as close to the track as permissible. The signal shall have a minimum visibility as indicated in para 7.1.11. (i) The height of normal aspect of the Colour Light signal shall be approximately at 3.65 meter from the rail level. Wherever this is not feasible due to local terrain, height of the signal post may be suitably increased or decreased to get a clear view of the signal. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 388 of 530  (ii) Exact location of new signal or shifted signal shall be decided, based on Signal Sighting committee report to be submitted as per Annexure: 19-A1 jointly by SSE(signal), traffic inspector and loco inspector, duly observing Schedule of Dimensions given in Annexure: 19-A2. (iii) Signals shall normally be placed on the left hand side of the relevant track. However in exceptional circumstances and due to site constraints, if any signal is to be placed on right hand side, in which case prior approval of competent authority, shall be obtained and such right hand signal shall be provided with an arrow mark (on rectangular plate with white back ground) pointing towards the track to which that signal pertains, to avoid any misjudgment by loco-pilot. (iv) A new signal, which is yet to be operational, shall be turned away from Track, must not be lit and shall be provided with a X across it. (v) The visibility of existing signals shall be checked jointly by SSE (Signal), traffic inspector and loco inspector and submit Signal Visibility Certification as per Annexure: 3-A1 and a time bound action shall be taken to improve the visibility, as per recommendation of the committee. (vi) A Signal post, which is having implantation less than schedule of dimensions, shall have infringing distance marked in red colour on white back ground. 19.2.2 Mounting and Fixtures (a) Colour Light Signals may be mounted on a rigid ground post or a signal gantry. Route Indicators/Calling ON unit/Shunt signal unit to be provided as required. (b) Each signal unit shall be rigidly fixed in position. Markers to be provided to identify type of signal such as ‘G’, ‘P’, ‘A’, ‘AG’, ‘D’, ‘ID’, ‘IB’. (c) Signal posts shall be kept plumb and packed with suitable material. (d) Suitable packing may be used to close the excess gap from post to signal unit, surface base to post. The cable entry at the signal unit should be provided with wooden plug around the cable to close excess gap to prevent rodent entry. (e) Enameled/Retro-reflective Signal number plate shall be provided. It should be white back ground (for other than Gate stop signals) with black letters, as shown in Drg. No. 19-D10 (sheet 3). For Gate stop signals, the back ground shall be yellow colour. (f) Alignment: Each signal unit shall be aligned correctly for better visibility. (g) The signal ladder shall be firmly fixed with clamps and the bottom of ladder ie the ladder shoe, shall be concreted firmly. The ladder alignment shall meet the requirements of schedule of dimensions. Where infringing, the signal ladder shall be blanked off (refer chapter no 1 item no 8 note (c) of schedule of dimensions), by providing a metal sheet around the signal post including ladder. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 389 of 530  (h) The cable entries of the signal unit should be closed properly using cement to avoid rodent entry. (i) Signal numbering plate (as per Signalling plan) to be provided with black letters on white back ground. 19.2.3 Hoods and Back Screens Hoods of adequate size to counter act the effects of sunrays shall be provided. Where required, metallic mesh at suitable spacing shall be provided to protect lenses from outside interference. 19.2.4 Cable Entry Cables shall be used from the point of operation to the location box/signal unit and/or location box to the signal unit. Cable shall be protected suitably at the entry points of location box and signal post. 19.2.5 LED aspect unit consists of a cluster of LEDs in series and parallel combinations. LEDs in a signal aspect shall be arranged in more than one array, so that in the event of failure of a single LED, whole unit does not become blank. LEDs in the arrays shall be so inter leaved so that effect of failure of any array is spread out equally to maintain uniform visibility. Integrated (with built-in current regulators) LED signal aspects for regulating the current shall be used. Red/ yellow/green LED aspects shall be used for Main /Subsidiary signals, and lunar white LEDs shall be used for route indicator. 19.2.6 Same make of LED aspects shall be used at a station/section for ease of maintenance. 19.2.7 Gaskets and Sealing: All openings shall be gasketted and cable/wire entrance shall be sealed to make the enclosure water tight, dust-proof and vermin-proof. 19.2.8 Locking: The housing shall be kept locked. Section 3: Installation of IRS Point Machines 19.3.1 Requirements: Electric Point Machines of approved type shall be used. (a) Electric Point Machines shall be installed in accordance with approved plans. Ground fittings of approved design shall be used. Ground connections shall be thoroughly checked for any crack or improper welded joint. Normally the machine shall be installed beside the close switch leading to high-speed movements clear of all infringements. Before installation of the machine, it shall be ensured that. (b) The JE/SSE (P.Way) has made all the provisions at the Points as detailed in para 12.13.2 to 12.13.4 & Annexure: 12-A1 of Chapter 12 of SEM. (c) The machine has been properly cleaned and lubricated in accordance with the manufacturer's instructions and is working freely. (d) Proper alignment and level of connections is maintained between the machine and the point gears. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 390 of 530  (e) The top of sleepers which are to support the point machine are at level and that surrounding ballast is well tamped to prevent sinking during the passage of train. (f) The machine shall be so installed that it is clear of all infringements. (g) Proper drainage shall be provided to avoid water logging near point area. (h) Wiring from the point of operation to the location box/apparatus case nearest to the machine shall be in cable. The cable shall be of appropriate size to keep the voltage drop minimum. The connection between location box/apparatus case and point machine shall be through underground cable adequately protected below track and near point machine, through GI/RCC/DWC-HDPE pipe of approved type or any other approved means. It shall be tested for insulation and continuity before bringing into operation. (i) Crossovers shall be operated by separate point machines, one at each end. The detection of setting and locking of the points at the two ends of a crossover shall be connected in series. (j) Means shall be provided to cut off the motor feed in case of obstruction to the point movement after a predetermined time lag, based on the type of point machine used. The point operating control circuits shall have track circuit control, overload protection and cross protection. (k) The crank handles shall be provided to facilitate operation of points in case of failure of point machines. For this purpose, the points in the yard may be divided into convenient groups and to distinguish particular groups, crank handles with different wards shall be used. The slots provided, in the point machines for insertion of the crank handles shall be suitably modified to take only the crank handle applicable to the group. The crank handles shall, however, normally be locked. It shall be possible to release them for use in point machine by releasing a control from the control panel. With the crank handle released, it shall not be possible to clear the signal for the concerned routes. The interlocking of crank handle can also be achieved by using NX key of different wards. (l) The excess gap around cable entry to the machine shall be plugged to avoid rodent entry/water ingress. 19.3.2 Point Machine, Notches, Gaskets, Sealing (a) Electric Point Machine shall be provided with suitable gaskets and wire entrances shall be sealed to make them water tight and dust proof. All the extra openings shall be closed as far as possible. (b) Locking: Electric Point Machine covers shall be locked. The cover provided for insertion of crank handle shall also be locked with separate key providing access only for crank handle and crank handle key. (c) Notches in Stretcher Blades: Notches/Notch profile of the locking, driving and detection slides should not be tampered/reconditioned. Worn-out slides should be replaced with new ones. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 391 of 530  Initial Adjustment of Point Machine 19.3.3 Adjustment of Driving Rod The points shall be adjusted by operating the machine first by hand cranking. The insertion of hand crank should disconnect the power supply to the machine. When the machine has been fastened down, the throw bar connections shall be set up and the point machine hand cranked to one end of the stroke positioning the locking blades so as to allow the appropriate locking dog to pass through notches. The closed switch shall be adjusted to just in contact with the stock rail. Then the connections shall be tightened further by 2 mm to 3.5 mm to impart a springing action to the tongue rail. The machine should be hand cranked to the opposite end of the stroke and the setting repeated for the other switch. Note: it is recommended that adjustment for driving rod and lock rod shall be done for the close switch nearest to the point machine first. 19.3.4 Adjustment of Detector Contacts The machine shall be hand cranked to the end of the stroke to close the tongue rail. Insert 1.6 mm test piece between stock rail and switch rail at 150 mm from toe of the switch and operate the point. Ensure detector contacts just make. A test gauge of 3.25 mm shall be inserted between the switch rail and stock rail at a distance of 150 mm from the toe of the switch. The detector connection of the closed switch shall be adjusted till the appropriate detector contacts are just broken. The same shall be repeated at the other end of the stroke. All the relevant nuts shall be tightened. Note: Where lock slide is provided in the machine, during switch detector adjustment the test shall first be done with fictitious locking. After completing the above test, same test be repeated with machine properly locked. 19.3.5 Adjustment of Friction Clutch (a) When IRS rotary type electric point machine under obstruction test draws less than 1.75 times the normal operating current, machine needs to be checked for proper functioning at site. (b) Obstruction Test: The point driving rod and the lock connections of the machine must be so adjusted that with 5 mm thick test piece obstruction placed between the switch and the stock rail at 150 mm from the toe of the switch: (i) The point cannot be locked. (ii) The point detector contacts should not assume the position indicating point closure and (iii) Friction clutch should slip. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 392 of 530 19.3.6 Testing of Point Machine (a) Obstruction Test: The point driving rod and the lock connections of the machine must be so adjusted that with 5 mm thick test piece obstruction placed between the switch and the stock rail at 150 mm from the toe of the switch: (i) The point cannot be locked (ii) The point detector contacts should not assume the position indicating point closure (iii) Friction clutch should slip (b) The Technician shall check whether the current required to operate the machine in either direction is the same (approximately). The reason for unbalance, if any, shall be investigated and eliminated. Note: In general, excessive current indicates the friction due to rubbing of rods with rods/sleepers, poor packing, lifting of tongue, improper lubrication, dirt/dust accumulation etc. causing extra load on the machine. The cause to be identified and rectified duly advising Traffic/P.way departments. (c) Test the spring in each switch and ensure sufficient spring. It shall not be too excessive to cause excessive wear on machine part, neither it shall too less to hold the switch against the stock rail. In either of the case, the point drive rod shall be adjusted. (d) Friction clutch where provided shall slip at a value prescribed by the Manufacturer. (e) Badly worn-out pins shall be replaced; the holes shall be reamed out and fitted with a oversized pin. Split pins where provided shall be properly split out. (f) Voltage and current shall be checked periodically at the motor terminals, as per Annexure: 19-MS2. This will indicate any undue friction on the points or improperly fastened terminals at cable terminations. (g) Cable and wire insulation and continuity tests shall be done. (h) The essential requirement for interlocking of point shall be periodically checked. (i) It shall be ensured that during obstruction in the point, the feed to point is automatically disconnected or friction clutch is tripped on overload described by manufacturer and reconnects only when a fresh operation is done. Where sequential operation of point machine is done, the maximum time before disconnection may not exceed to 3.5 times the normal operating time of one machine. (j) Each sectional JE/SSE (Signal) shall test the operating values of the machine and adjustments of the machine by obstruction test every month. The Sectional incharge of the section shall carry out these tests once in three months. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 393 of 530  Section 4: Thick Web Switches (TWS) 19.4.1 Conventional over-riding type of switches suffer from geometrical deficiencies like: (a) Weakness of tongue rail due to severe reduction of section by heavy machining. Tongue rails are further weakened by heavy wear and tear by traffic. So these are to be replaced frequently. (b) Obstruction to the wheel flange at the actual toe of the switch due to thickness of the tongue rail as well as due to switch entry angle. Hence a jerk is experienced by vehicles on account of these obstructions. (c) Twist in the track over a short distance on tongue rails machined from rail of same cross section, due to overriding nature of the tongue rail. (d) Structural weakness of the entire switch assembly to withstand lateral forces at higher speeds. 19.4.2 Thick Web Switches (TWS) overcome deficiencies of conventional over-riding type of switches. These are non-over riding type: (a) Thick web switch has wider switch opening of 160 mm (as against of 115 mm of conventional over riding type of switches). (b) Ground connection along with clamp lock used for operation of TWS and direct locking of tongue rail with stock rail shall be of approved type. (c) For operation and clamp locking of TWS, electric point machine of approved type with requisite throw shall be used. 19.4.3 For ground connection and clamp lock as per RDSO Drg. No. RDSO/S-3454 for 60 Kg rail and RDSO/S-3455 for 52 Kg rail, IRS point machine of 220 mm throw is used. (a) Out of 220 mm throw, during first 60 mm throw closed switch rail gets unlocked and open switch rail moves towards stock rail. During subsequent 100 mm throw both switch rails move simultaneously thereby open switch gets closed and closed switch gets opened by 100 mm. During final 60 mm throw, closed switch gets locked and open switch rail moves 60 mm further resulting in total opening of open switch by 160 mm. (b) Provides direct locking between tongue rail and stock rail in closed and open position. (c) No stretcher bar is used and both the tongue rails move independent of each other. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 394 of 530 19.4.4 Spring Setting Device (SSD) SSD of approved type shall be provided at junction of Rail head (JOH) to assist in proper setting of switch up to junction of Rail head (JOH). (a) SSD is placed between sleeper number 13 and 14. (b) SSD is insulated from both the rails. (c) SSD installation and maintenance is responsibility of Engineering Department. 19.4.5 Ground connection and clamp lock for Thick web switches shall be installed as per concerned RDSO drawings/approved drawings and installation guidelines. 19.4.6 Obstruction Test The detector slides, lock slides and drive rod must be so adjusted with 5 mm thick test piece placed between the switch and gauge face of stock rail at 150 mm from the toe of the point. The following to be observed: (a) Friction clutch de-clutches the motor from mechanism. (b) The point cannot get locked either by clamp lock or by locking segment inside the point machine. (c) Lock segment does not enter into the notches of locking slides. (d) Switch detection contacts do not make. (e) The slipping current is not exceeding twice of the normal working current. 19.4.7 Insulation Test (a) Point machine: Check that point machine is insulated from ground connection. (b) Spring setting device: Insulated from both the rails. (c) Clamp lock assembly: Check that it is insulated from both the rails. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 395 of 530  Section 5: Installation of Electrical Point Detector (EPD) 19.5.1 Electrical point detector of approved type shall be used. Normally it shall be installed beside the close switch leading to high-speed movement, clear of all infringements as per approved plan and drawing. (a) Detectors shall be mounted either on the left or on the right-hand side of a point layout clear of infringements. (b) The detectors shall be mounted on extended sleepers or as per any other approved arrangement. (c) Contacts shall be adjusted so that they make or break at the same time. Shunt contacts shall be adjusted so that they do not make before the detector contacts break. In AC traction area shunt contact shall not be used. Care shall be exercised to check that the detection contacts flex a little after they are closed. (d) All nuts and screws shall be tightened. Check nuts with spring washer shall be provided. (e) After installation before connecting the detector slide, the slides shall be pulled by hand to check for free movement. Binding, if any shall be attended to. (f) The lock slide shall be pulled and it shall be checked that as soon as the roller is lifted above the slot in the lock slide, the normal or reverse contacts are open and the shunt contacts are made. The electrical detector must be so adjusted that with 3.25 mm thick test piece obstruction placed between the switch and the stock rail at 150 mm from toe of the switch - The electrical detector contacts shall not make. (g) To keep the slides in correct position the locating marks on the switch and lock slides shall be made use of. 19.5.2 Circuit Controller: These shall not be newly installed normally (except in few Installations like LC Gates) and the existing one to be replaced in phased manner. Railways still having these equipments may please refer the earlier version of SEM Part-II, September 2001. Section 6: Signalling Relays For information on Signalling Relays, Refer to Annexure: 21-A1. 19.6.1 Relays – General Requirements: Refer to para 21.2.1 19.6.2 Installation of Relays: Refer to para: 21.2.2 19.6.3 Sealing of Plug-in Relays: Refer to para 21.2.3 19.6.4 Maintenance of Relays: Refer to para 21.2.4 19.6.5 Periodical Inspection of Relays: Refer to para 21.2.5 19.6.6 Replacement of Relays: Refer to para 21.2.6 Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 396 of 530  Section 7: Fuses 19.7.1 (a) Fuses shall be of approved type and appropriate rating. When fuse is not provided with fuse blown off indication, additional indication circuit may be provided. (b) At the time of commissioning of any signalling installation, the normal load current of every circuit shall be measured and recorded. These recorded values shall be checked with the theoretically obtained values. Fuse of correct capacity which should be not less than 2.5 times the rated current, shall be provided. (c) When there is a case of fuse blowing off, the concerned circuit current shall be measured and compared with the original recorded value. If there is a variation, action shall be taken to locate and remove the defect before a new fuse is inserted. (d) For LED signal aspects, fuse of prescribed rating (0.6 Ampere if not prescribed otherwise) shall be used. 19.7.2 Fuse change over system: Fuse Auto Changeover System with monitoring panel and alarm facility along with audio & visual indications suitable for signaling installations of Railways may be used for minimising failures due to fuse blown off. The changing over of circuit operation from main fuse to spare fuse shall be automatic, without affecting the functioning of signaling circuits, when main fuse is blown off. At every change-over, audio/visual indication shall appear and Equipment shall work either on 24 V DC, 60 V DC or 110 V AC, Reverse polarity protection and overload protection voltage may also be provided in the power supply circuit. The system shall be of approved type. These shall be maintained as per Annexure: 19-MS5. Note: Electrical signalling equipment shall be painted in accordance with the approved Colour Scheme Section 8: Testing of Signalling Circuits 19.8.1 General The checking and testing of signalling installations may be divided into five different groups as detailed below: (a) Physical inspection of the installation. (b) Checking of the wiring and cables. (c) Testing of the individual circuits. (d) Testing of the individual apparatus. (e) System testing of the installation. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 397 of 530 19.8.2 Test Procedure (a) Systematic methods such as marking on Control Tables/Locking/selection tables and suitably and clearly marking on the circuit diagrams while checking the circuits and equipment should be adopted to ensure that all circuits have been completely checked. (b) Suitable proforma should be devised for recording the tests of electrical equipment before testing of the installation is taken up to ensure availability of records of the tests and their analysis. 19.8.3 Testing Instruments Suitable instruments like Multi-meter, Volt meter, Ammeter, Ohmmeter, Frequency meter, Bell tester, Earth Tester, Earth leakage detector, Cable fault locator, Cable route tracer, Relay contact testing/cleaning kit, etc. should be used in the testing of electrical signalling circuits. Calibration of these instruments should be checked periodically. 19.8.4 Physical Inspection of the Installation It shall be checked that the work has been carried out in accordance with the approved plans and that equipment is of proper type and is in good condition. The following aspects shall also be checked during site inspections: (a) The signals, location boxes and other out-door equipment are as per approved plans and are in good condition. Arrangements for proper ventilation, where provided, are not choked. (b) Each location contains all the apparatus required as per approved plans, the apparatus is of approved type and that the power supply equipment, batteries, fuses, etc. are installed according to the approved plan and specification. (c) The location of insulation joint, jumper wiring, traction bonding in electrified areas, point machines, switch locks and other apparatus is as per approved plans and their condition is satisfactory. (d) The electrolyte, inter-connections between cells, cell voltage etc. are in required condition as per relevant specifications or instructions. (e) Each wire is tagged or marked where feasible so that it can be identified at each end and the nomenclature on the tag corresponds to that on the wiring diagram. The tags or other sleeves of identification shall be of insulating material. (f) The number of wires terminated on each terminal or relay terminal boards or other devices are counted and tallied with the number of wires shown in the wiring diagrams. (g) All connections on terminals and binding posts are properly secured. (h) The lightning arrestors are properly connected and earthed as per plan. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 398 of 530  (i) Detailed specifications & instructions for inspection and testing of different types of equipment as applicable to them should be available. (j) All other equipment such as lever frames, LC gates, cable sheaths, signal screens, location huts, etc. in AC. electrified areas shall also be properly earthed as stipulated in Chapter 22 of SEM. (k) No equipment is due for overhauling. 19.8.5 Checking of the Wiring: (a) Point to point testing: Wiring shall be checked to ensure that it has been carried out as per approved wiring diagram. Point to point testing shall be carried out before plugging in the relays. Wires shall be tested one by one for continuity and insulation. While doing continuity testing, wire count test shall also be done to verify the number of wires present on each contact. (b) Wire Count Test: Prior to conducting continuity and insulation test, contact occupancy test must be carried out for each relay as per the contact analysis made. The number of contacts allotted and wires at each contact must tally. Recommended practice: while dealing with wiring alterations, it is recommended to adopt a clear system for deletions, additions such as colour code. For example, Green colour for deletions and red colour for additions. Similarly a system of checking of such deletions/additions by a tick and second level checking by cross tick on drawing sheets/separate wiring sheets or any other suitable protocol may be adopted duly explaining to staff concerned, to give clarity and avoid rework. 19.8.6 Test of Individual Circuits (a) It shall be checked that each individual circuit is actually controlled by the proper contacts of the relays and other devices as per wiring diagram. (b) Where feed to a particular device is controlled through two or more paths in parallel, the check of each path must be carried out separately. (c) Cases of intermittent or continuous extraneous feed of even small magnitude or wrong operation of any relay observed shall be investigated thoroughly and remedial action taken to rectify the fault. (d) Once the indoor wiring works are completed before conducting the system Integrity testing, simulation test must be conducted by simulating field gears such as Track circuits, Signals & Points on a simulation panel. This will ensure the correctness of indoor wiring before connecting to outdoor gears. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 399 of 530 19.8.7 Installation, Testing of other equipments & Cables Installation & Testing shall be done in accordance with specification & instructions applicable to each individual equipment: (a) Train Detection: Track circuits, AFTC, Axle Counters as per Chapter 17 of SEM. (b) LC Gates as per Chapter 14 of SEM. (c) Cables: All signalling cables shall be laid, Tested as per Chapter 15 of SEM. Note: At least two cores of cable shall be provided between two ends of the yard to cater for telephone communication for maintenance purposes in non RE areas. Where the yard is extending over a large area, the location boxes may be grouped and one socket may be provided in one of the location boxes in the group so that telephone communication is conveniently available for co-ordination with the cabin during maintenance or rectification of failures of various ground equipments. Where such groups are situated in different directions from the cabin, a separate pair of conductors shall be used for each direction connected to the cabin. In RE area, provision shall be made for telephone communication through a telecommunication cable if already available or a separate telecom cable shall be laid for the purpose. (d) Power Supply Arrangements: Power supply systems for Signalling Installations shall be as per Chapter 16. 19.8.8 System integrity Testing (SIT): This is a complete testing involving both Indoor & Outdoor signalling equipment for functional working & safety. To be done in a new installation, at every interlocking alteration or periodically once in five years. (a) After the individual tests mentioned in previous paras for outdoor equipments and Testing of Relay Interlocking/Electronic Interlocking as given in Chapter 21 of SEM have been carried out, the signalling installation as a whole must be tested with detailed operational, functional and safety tests as per approved Control Table/Route Chart and Signalling & Interlocking Plan. (b) These tests shall be planned carefully with men, material, Tools, public address system, Walkie-Talkie Sets, Transport vehicles & other logistics. In a working installation, Non-interlocking/Disconnection duration shall be reasonable and commensurate with yard complexity and to be decided in consultation with Operating department and planned much in advance. All required sanctions/approvals shall be ensured before hand. (c) Requisite number of staff considered essential for carrying out such tests shall be mobilized at site, briefed suitably as per planning made and working protocols explained and deputed to concerned locations with relevant wiring diagrams & Tools. They should be equipped with requisite tools, meters, portable telephones and/or walkie talkie sets, so that they are in contact with the official incharge of testing and other testing parties and take such action as directed. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 400 of 530  (d) Complete System Integrity testing shall be initiated only after all the field functions are connected to the Relay Interlocking/Electronic Interlocking (during Non-interlocking/Disconnection period in a working installation) and simulation testing is completed and all errors removed. (e) Complete tests shall be carried out against approved Selection Table/ Control Table/Route Control Chart. Checks against signalling plans for main signal routes and a few spot checks of the remaining routes shall also be carried out. (f) Field Correspondence Tests: Full correspondence of field gears such as aspects of Signals, Condition of Points, Status of Track circuits, LC gates etc. with that of Control Panel/Control Terminal/VDU with respective position of knobs, switches, and indications, must be verified and corrected to obtain 1:1 correspondence, before signing safety certificate (and ending Non- interlocking/disconnection in a working installation) and allowing any signalling installation being opened to Train traffic. 19.8.9 Following simple two line station example is given for an understanding on how to conduct system integrity tests: (a) Signal Control Circuits Each route shall be set individually by operating control lever or switch(es) and/or button (s) as the case may be. After checking that the signal for this particular route has been cleared, each track circuit controlling the signal shall be shunted individually to check that the signal goes back to danger. Similar tests shall again be made by de-energizing point detection relays and other relays controlling this route. Each such relay will be de-energized individually and it shall be checked, that the signal goes back to danger. (b) Approach Locking Each route shall be set up individually. After ensuring that the signal for this particular route has been cleared, each track circuit controlling the approach locking shall be de-energised in turn. The signal shall be put back to 'ON'. Efforts shall be made to alter the route under test and to set up conflicting route. It shall be checked that it is not possible to cancel the route set up and/or to set up a conflicting route and/or to individually operate any point in the route under test. This locking shall be effective till the set route is cancelled and the time release circuit has operated, provided the track beyond the signal is not occupied. (c) Dead Approach Locking Where dead approach locking is provided, the same test procedure as in para 19.8.9 (b) shall be adopted except that there is no controlling track circuit to be de-energised. After the signal has been taken 'OFF', the approach locking shall be effective till the signal is put back to 'ON' and time release circuit has operated. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 401 of 530 (d) Route Release (i) Tests shall be carried out to ensure that once a signal is cleared for a particular route, position of none of the points in the route can be changed when track circuit immediately in advance of the signal is de- energised. (ii) Where sectional route release is provided, it shall be ensured that a sub route does not release only by picking up of the concerned track relay (s) but the same should be released only after the next track circuit has also dropped and picked up except for the berthing portion of track circuits. (iii) Where sectional route release is not provided, tests shall be made to ensure that the entire route remains locked when any of the track circuits beyond the signal up to the track circuit controlling the last point is de-energised. (iv) In cases where the route is controlled by single track circuit, the route shall be released after prescribed time delay to be effective after the concerned track circuit has been occupied and cleared by the train. (e) Time Release Time release, where provided, shall be tested to ensure that it will be possible to alter the route or set up a conflicting route or change the position of the points in the route only after the signal is put back to 'ON' and the prescribed time interval has lapsed. Similar tests shall be carried out for overlap release, where time release is provided for releasing the overlap after clearance of last track circuit in rear of berthing track and occupation of the berthing track, if any. Also overlap shall get released only after concerned signal knob/button is normalized wherever required. (f) Signal Indication Circuits Indication of 'ON' position of all signals shall be checked for its correspondence with aspect displayed at site. Each signal shall then be cleared after setting its route and the indication of each aspect shall be checked for its correspondence with the aspect displayed at the site. This test shall be carried out for each signal as well as for direction type route indicator where provided. In the case of later, it shall also be ensured that the indication relay is not energised and the indication does not appear until the minimum number of lamps/LEDs as required are actually lit. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 402 of 530 (g) Point Controlling Circuits (i) Each point shall be set to reverse position by operating the controlling lever/switch/buttons. After the point has been fully reversed, each track circuit controlling the point shall be individually shunted in turn and operation of points to normal position shall be attempted. It shall not be possible to operate the point under these conditions. These tests shall be repeated with the point set in normal position, attempt being made to operate it to the reverse position. (ii) With the obstruction in the points, the point shall be operated from normal to reverse and reverse to normal and it shall be checked that the over-load relay where provided gets energised and the feed to the motor is cut off immediately. Where over load relay is not provided, the feed to the motor shall be cut off after the lapse of a prescribed time. (iii) The out of correspondence test shall be carried out by opening cut out contact of one end of point machine and the point lever/knob/button operated. The other end of the point may operate but the point indication relay shall not energise. (h) Point Indication Circuit (i) The point shall be operated from normal to reverse and reverse to normal and the position of point detection relay as well as the indication of the point in the cabin/panel shall be checked for correspondence with the position of the points at site. It shall also be checked that with the obstruction in the point, the detection relay is de-energised and both normal and reverse point indication in the cabin/panel are extinguished in case of electromechanical signal and flash in case of PI/RRI installations. (ii) The operation of the detection relay to the correct position as well as its de-energisation should be checked by making and breaking the relevant point detector contacts at site. (i) Crank Handle Interlocking It shall be checked that when the crank handle is removed from its normal position in Electric Key Transmitter/other approved Relay interlocking arrangement, the signals reading over the concerned route/zone cannot be taken 'OFF' nor the points can be operated from the cabin/panel. It shall also be checked that when the signal reading over the concerned route/zone is taken 'OFF', the crank handle cannot be released from its normal position in Electric Key Transmitter/other approved Relay interlocking arrangement. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 403 of 530 19.8.10 Testing Procedure for Panel Interlocking/Route Relay Interlocking Installations It shall be ensured that the interlocking system as per approved plans and drawings. Typical testing procedure for a Relay interlocking installations is given below with an example for a two line station for an understanding. (The actual testing at site shall be as per station layout) 19.8.11 Testing of Relay Interlocking LOCKS Sl. SIGNAL CONTROLLED LOCK & DETECTS ROUTE ROUTE HELD BY ROUTE REMARKS No. NO. BY TRACKS POINTS POINTS 1. 2W 2WBI APPROACH BACK LOCK 2WT, A2ET NORMAL REVERSE 4EB 2E Controlled TRACKS TRACK 2T, 2BT,BT 1 2 by closed A2WT 2WT A2ET IBT position of (120 Sec 2T 2BT LC gate time delay) 2. 2W 2WBII A2WT 2WT A2ET 2WT, A2ET 1,2 4EB 2E Controlled (120 Sec 2T 2BT 2T, 2BT, BT - 3WB by closed time delay) IBT, IT A1 WT position of LC gate (a) Point Locking Operate point No. 2 to reverse position and clear the signal route No. 2WBI by operating signal switch/button. Operate point knob 2 to normal. The point should remain locked. Restore the point knob to reverse. De-energise 2RWKR. Signal 2WBI shall go to 'ON'. Restore the signal switch/button to normal. When point No No.. 2 is free, shunt the track 2T. Turn the point knob 2 from reverse to normal. The point should remain locked. (b) Approach Locking: Take 'OFF signal for route No. 2WBI by setting the points in required position. Normalize the signal switch/button with A2WT clear. The signal assumes 'ON' position. Try to alter the route, it should be free. Again take 'OFF' signal for route No. 2WBI. Shunt the approach Track A2WT. Normalize the signal switch/button. Try to alter the route. Route should be held till the route is cancelled and 120 seconds time delay has lapsed. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 404 of 530 (c) Interlocking of Signals: Clear the signal route 2WBI after setting the route. Try to clear the signal 4EB by operating the relevant switch/button. Signal 4EB should remain in 'ON' position and signal 2W should continue to display 'OFF' aspect. Similar tests shall be carried out for signal 2E also. (d) Track Circuit Controls: (i) Clear the signal route 2WBI again. Shunt the track 2WT. Signal should go to 'ON'. Remove the shunt, the signal should not re-clear. Normalize route and re-clear again. Shunt A2ET and other controlling track circuits one by one. Signal should go to 'ON' in all cases. Remove the shunt. Normalize the route. (ii) Where track circuits provided with redundancy, its proper working shall be thoroughly tested for redundancy and effectiveness in the signalling circuits. Detailed instruction and precaution for testing and fault rectification shall be issued by Zonal Railway. (e) Back Locking: (i) Clear the signal 2W for route 2WBI again. Shunt the track 2WT. The signal should go to 'ON'. Normalize the signal switch. The route should be held. Shunt and clear all the back locking tracks as per selection table in sequence. The route shall be released by sequential proving of tracks as per the provisions of para 4.3.3 of Relay interlocking specification IRS: S 36-87. (ii) Clear the signal route 2WBI again and de-energize the Level Crossing Gate control relay. The signal should go to 'ON'. Re-energize the relay, the signal should assume 'OFF' aspect. (f) Conditional Locking: Wherever conditional locking is provided (for alternate overlap/parallel movements etc. for yard flexibility), the points setting and its route holding, correct proving in the signal circuits shall be thoroughly checked. (g) Datalogger Circuits: The data loggers connected to various power supplies, relays of internal/ external circuits, block instruments, battery chargers and other applications like open/close status of relay room, battery charger/IPS/Invertors monitoring etc. shall be regularly checked/tested. Also ensure the nominated JE/SSEs/ staff are receiving the various exception reports generated from the data logger to aid their day to day works/ maintenance/fault restorations in coordination with Fault control JE/SSEs/staff incharge of Datalogger monitoring. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 405 of 530  (h) Miscellaneous Circuits: (i) Miscellaneous arrangements like effectiveness of Station Master’s key, cascading of signals on the route, Red lamp protection on the route etc. shall be thoroughly tested for the independent signal/routes. (ii) The protection arrangements like Lightning arrestors, Surge protection devices and its associated Fuse/Earthing arrangements shall be regularly tested and Maintained. (iii) The relay contacts shall be paralleled, if spare contacts are available. 19.8.12 Precautions during Testing Following precautions shall be taken during testing and checking so that (a) No signal taken 'OFF' for a train movement is thrown to 'ON' in the face of the train. (b) No signal which will create a conflicting or unsafe movement is taken ‘OFF’. (c) No point and isolation in a route set for a train movement is disturbed. (d) No track relay of an occupied track circuit is energised. (e) No voltage higher than permissible levels is applied to the equipment. (f) There should be no risk of electric shock to testing or operating personnel. Section 9: Maintenance of Outdoor Signalling 19.9.1 Insulation tests on Cables shall done as per Chapter 15 of SEM. 19.9.2 Maintenance of Colour Light Signals (a) Cleanliness of LED Lenses (i) Polycarbonate Lenses of LED lamp shall be kept clean. A dry soft cloth free from lint and abrasives shall be used for cleaning. (ii) Housing shall be kept clean and opening in inclement or stormy weather avoided. The condition of the gasket shall be checked to ensure that rain water does not have access to the interior of lamp unit. (b) Replacement (i) Defective LED lamps must be replaced immediately. (ii) The LED lamps shall be replaced as per prescribed codal life. (c) New lamp shall be pre-tested as per approved instructions before putting into use. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 406 of 530  (d) The following checks shall be made periodically. (i) The LED lamps bulb shall be seated fixed and fastened properly. (ii) The signal visibility shall be checked and adjusted periodically. (iii) All adjusting nuts are properly tightened. Maintenance checks to be done as per Annexure: 19-MS1. 19.9.3 Maintenance of Electric Point Machine (a) Cleanliness: Machines shall be kept in good condition free from rust, dust and dirt. (b) Lubrication: All gearing and bearing shall be properly lubricated according to manufacturer's instructions. (c) Commutator, Brushes & Electrical Connections (i) Commutator shall be kept clean, smooth and have bright appearance. Commutator may be cleaned with chamois leather. Under no circumstances, shall emery paper be used. (ii) Brushes shall be kept clean and properly bedded on the commutator. Brushes shall have proper pressure and shall be free in brush holders. (iii) All cables connections on terminal, motor terminal etc. shall be checked for intactness. (iv) All tail cables shall be checked for their insulation as per periodicity given in Annexure: 15-MS1. (d) Adjustment of Contacts: Contacts shall be clean, free from pitting and in proper adjustment. (e) Rain water drainage arrangements shall be checked especially prior to and during rainy season. (f) Fixing Nuts & Screws (i) Fixing nuts and screws of newly installed point machine often tend to get loose. Care shall be taken to attend to them and readjust where required. To prevent this, check nut with spring washer shall be provided. (ii) All moving parts including locking Dogs and notches slides, etc. shall be checked for chamfering or undue wear. Where badly worn-out, the relevant parts shall be promptly replaced. 19.9.4 Testing of Point Machine: Each sectional JE/SSE (signal) shall test the point machine and do adjustments of the machine by conducting obstruction test as per para: 19.3.6 & Annexure 19-MS2. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 407 of 530 19.9.5 Maintenance of Electrical Point Detector (EPD) Maintenance schedule as shown in Annexure: 19-MS3 shall be followed. 19.9.6 Maintenance of Circuit Controller Railways having these equipments may refer to earlier version of SEM Part-II, September 2001. These shall not be used in new installations and the existing one to be replaced in phased manner, except in few cases like LC gates. 19.9.7 Maintenance of Station Master's Slide Control Frames Railways still having these equipments may refer to previous version of SEM Part-II, September 2001.These shall not be used in new installations and the existing one to be replaced in phased manner. 19.9.8 Maintenance of Electric Key Transmitters, Fuse & Fuse Alarm Systems Maintenance schedules as shown in Annexure: 19-MS4 shall be followed for Electric Key Transmitters. Maintenance schedules as shown in Annexure: 19-MS5 shall be followed for Fuse & Fuse Alarm Systems. 19.9.9 Maintenance of Thick Web Switch Point Machine: Maintenance instructions issued by RDSO and Zonal Railways shall be followed. 19.9.10 Maintenance Schedules The maintenance schedule for various Signalling equipment are given in Appendix-I. At stations having dense traffic and high speeds, Zonal Railways may prescribe more intensive schedules as considered necessary. Section 10: Lightning & Surge Protection for Outdoor Equipment 19.10.1 Lightning and Surge protection shall be provided for Axle Counter Systems, IPS and Electronic Interlocking, IB huts/Goomties etc. 19.10.2 Installations to be Protected: (a) Equi-potential bonding to be provided for all the equipment for effective lightning and surge protection in Signal Equipment Rooms, such as End goomties/cabins. (b) External Lightning Protection and Class/Type I, II & III devices are to be provided at (i) External Lightning Protection on Top of Buildings housing S&T Equipment. (ii) Class B/Type-I devices at the Input of Power Supply Equipment. (iii) Class C/Type-II devices at Output of Power Supply Equipment. (iv) Class D/Type-III devices at Indoor and Field Equipment. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 408 of 530  Section 11: Earthing for Outdoor Signalling Equipment 19.11.1 Types of Earths (a) Earths are of two types (i) Functional Earth: The earth return used for block instruments is a functional earth which is used to conduct the current through earth during normal operation/function of equipment. (ii) Protective Earth: This earth for dissipating surges, which comes in contact with equipment’s connections through Surge Protection Devices (SPD) during Lightning or surges so as to protect the equipment. (b) Perimeter Ring Earth (PRE) shall be provided around building housing signalling equipment. Chasis of all S&T equipment shall be bonded to BRC (Bonding Ring Conductor) provided inside the Power Equipment Room or Signal Equipment Room. BRC is to be connected to MEEB in Power room and from there to PRE as per extant guidelines. In case, no BRC exists, chassis of the equipment shall be connected directly to MEEB (Main Equi- potential Earth Busbar). (c) Earthing shall be provided as per approved specifications, drawings and code of practice issued by RDSO. (d) The maximum earth resistance shall be specified as per OEM & RDSO recommendations. 19.11.2 Purpose of Earthing Earthing of cables, equipment, buildings and structures is done for one or more of the following purposes: (a) Lightning & surge protection of equipment. (b) Earthing of metal screens of telecommunications cables and equipment for reducing Electromagnetic interference. (c) Human safety. 19.11.3 Earthing to be provided at (a) The lever frame and other metallic frames of the cabin shall be earthed. (b) The earthing shall be provided at every location box where cables terminate. (c) The earthing shall be provided at each signal. (d) Wherever possible, the common earthing system to be provided for closely located location boxes, signal posts, etc. Separate earth is required for equipment requiring functional earth only. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 409 of 530  (e) Sheath & Armour of Main cables to be earthed. Armour of OFC shall be earthed at both ends. It is not necessary to earth the armouring of unscreened cables when they are used as a tail cables except in special cases where the length of the tail cable exceeds normal prescribed limits. (f) In case of signals falling within 2 meters from the electrified track, the protection screen shall be connected to an earth. (g) There shall not be any possibility of simultaneous human contact with metallic bodies connected to different earths, where it is not possible to provide suitable spacing or partition between various metallic objects referred to above, they shall be connected to a common earth. (h) Common/Equi-potential earth for modern electronic equipment such as EI, DAC, Datalogger etc. to be used in Relay room. Earth value shall not be more than one ohm and shall be measured annually during dry season. (i) Earthing wires from subsystems to earth terminal shall be of distinctive color. Green or Green Yellow (GNYE) color is recommended for quick identification of a loose or disconnected earth wire. (j) All earth wires shall be as straight as possible and shall never be coiled. Earth wires should be of adequate current carrying capacity and should not be less than 4 Square mm copper cross-section or its equivalent. (k) Earth resistance up to 10 ohm is normally permissible for protective earth except when specified otherwise. For electronic equipment, Earth resistance shall not be more than one ohm. (l) Earthing of approved type shall be provided for each block instruments and other signalling equipment at a station. Dedicated earthing arrangement to be provided for earth return circuits individually if any. (m) The resistance of earth for signalling circuits shall not exceed 10 ohm or as prescribed by OEM/RDSO. If the resistance is more than the required value, steps to reduce the earth resistance shall be taken. If it is still not possible to reduce the value below the required value, even with the adoption of these methods, additional earths may be provided in parallel. (n) Where more than one earth electrode is used, the distance between two earthing electrodes shall be as per approved design. 19.11.4 Earthing Leads (a) Earth wires shall be protected against mechanical damage and possibility of corrosion particularly at the point of connection of earth electrode. (b) The earthing lead shall be mild steel flat of size 40 mm x 6 mm or as per the approved earthing practice/drawing. (c) The earthing lead shall be soldered or crimped on a lug, which shall be bolted to the earth electrode or preferably exothermically welded. The nut & bolt to be painted with anti corrosive paint. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 410 of 530 19.11.5 Selecting Site for Earthing (a) The site for earthing shall be chosen in the following order of preference: (i) Wet marshy ground and grounds containing refuse, such as ashes, cinders and brine waste. (ii) Clay soil or loam mixed with small quantities of sand. (iii) Clay and loam mixed with varying proportions of sand, gravel and stone; and (iv) Damp and wet sand and peat. (b) A site which is naturally well drained shall be chosen. A water logged situation, however, is not essential unless the soil be sand or gravel. Perennial wells may also be used as sites for earth electrodes with advantage where the bottom of the earth is rocky. (c) Electrodes shall preferably be situated in a soil which has a fine texture and which is packed by watering and ramming as tightly as possible. Where practicable, the soil shall be sifted and all lumps broken up and stones removed in the immediate vicinity of the electrodes. (d) Where soil conductivity is poor, the chemical treatment may be resorted to improve the same. Common salt together with charcoal in alternate layers is generally used for this purpose and the addition of less than one part by weight of salt to 200 parts of soil mass may reduce the resistivity by 80% but there is little advantage in increasing the salt content above 3%. Calcium chloride and sodium carbonate are also beneficial. (e) Use should be made where possible of natural salts in soil produced by bacteriological action on decaying plants. The resistivity of the soil on which plants are growing will be less than that of a similar soil in the absence of plants. (f) As far as possible, the earthing arrangement shall be located in the natural soil. The made-up soil which has not consolidated or is likely to be eroded by weather, shall be avoided. (g) The minimum clearance of equipment earths from system earths (e.g. earthing of AT/Transformer etc.) provided by the Electrical Department either of the Railways or of the other Administrations shall be 20 meter. (h) Asphalt or concrete cover of about 50 mm thickness around the Earth for a radius of 1 meter to retain the soil moisture is desirable. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 411 of 530 19.11.6 Earth Resistance Earth Resistance of an 'earth' is the sum of three separate resistances, viz., (a) the resistance of the conductor joining the earth electrode to the installation. (b) The contact resistance between the surface of the earth electrode and the soil, and the resistance of the body of soil surrounding the earth electrodes. (c) Normally the first two resistances are negligibly small compared with the third; so, the resistance of an 'earth' is primarily determined by the nature of the soil and not by the electrode itself. (d) The material used for a standard electrode system should be corrosion resistant. Under ordinary soil conditions, use of galvanized iron or mild steel electrode is recomme recommended. nded. In cases where soil corrosion is likely to be excessive, it is preferable to use either copper or copper clad electrode. The electrodes shall be free from paint, enamel or grease. (e) Earth tester normally used for measurement of earth resistivity comp comprises of the current source and meters in a single instrument and directly read the resistance value. 19.11.7 Connection for Four Terminal Megger When using a megger as shown below, the resistivity may be evaluated from equation P = 2πSR Where, P = resistivity of soil in ohm meters, S = distance between successive electrodes in meters, R = megger readings in ohms. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 412 of 530  (a) Test Procedure: At the selected test site, four electrodes are driven into the earth along a straight line in a chosen direction at equal intervals 'S'. (b) The depth of the electrodes in the ground shall be of the order of 10 to 15 cm. The megger is placed on a steady and approximately level base, the link between terminals P1 and C1 opened and the four electrodes connected to the instrument terminals as shown in the fig. An approximate range on the instrument is then selected to obtain clear readings, avoiding the two ends of the scale, as far as possible. The readings are taken while turning the crank at about 135 rev/min (in case of Magneto Generator Type) or pressing concerned button in some Other Type of Meggers. Pl see equipment Manufacturers manual and follow as stated there in. (c) Resistivity is calculated by substituting the values of 'R' in the equation P = 2πSR. (d) The earth resistance shall be measured using suitable method. For measurement of small earthing system like that of single electrode or ring earth, ‘Fall of Potential’ method can be used. The typical diagram and measurement method is given in Annexure: 19-A3. 19.11.8 Maintenance of outdoor earths (a) Watering: Conventional Earths shall be regularly watered. Earth enhancement material should be periodically added to Maintenance free earth to improve the earth resistance. Earth pit to be regularly cleaned. (b) Earth Connections: All Earth connections shall be carefully examined and kept intact and joints soldered. The wire between each earth and the connected equipment shall be electrically isolated. The exothermic welding termination on maintenance free earth rod shall be checked and cleaned. 19.11.9 Regular Checks/Upkeep of Earths (a) Block earths and their connections shall be examined at intervals of not more than one month by JE (Signals) and not more than three months by Sectional SSE(Signal)/Incharge. (b) Block earths shall be tested for resistance at intervals of not more than 12 months by Sectional JE/SSE (Signal). Where the resistance exceeds 10 ohms, action shall be taken to reduce the resistance by providing additional earths in parallel. (c) If routine testing indicates that existing earth electrode system is not satisfactory, a new earth electrode system (or part of a system to supplement the existing system) shall be provided. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 413 of 530  Note: This Chapter has under mentioned Annexures S.No. Annexure No. Description 1 19-A1 Signal Sighting Committee Report - For Shifting of Existing Signals/ Erection of New Signals 2 19-A2 Extract of Schedule of Dimensions (SOD) 3 19-A3 Method for Finding Out the Resistance of an Earth Note: This Chapter has under mentioned Maintenance Schedules in Appendix-I S.No. Annexure No. Description 1 19-MS1 Maintenance Schedule of Colour Light Signal Maintenance Schedule of Electrically Operated Points (Inclusive 2 19-MS2 of Clamp type Point) 3 19-MS3 Maintenance Schedule of Electrical Point Detector (EPD) 4 19-MS4 Maintenance Schedule of Key Locked Checking Relay/Electric Key Transmitter (KLCR/EKT) 5 19-MS5 Maintenance Schedule of Fuses & Fuse Alarm System 6 19-MS6 Maintenance Schedule of Earthing and Lightning Protection Note: This chapter has under mentioned Drawings in Appendix-II S.No. Drawing No. Description 1 19-D1 Apparatus Case Full Size Foundation 2 19-D2 Apparatus Case Half/Quarter Size Foundation 3 19-D3 Main Signal Post Foundation (Sheets-2) 4 19-D4 Shunt Signal Foundation 5 19-D5 Drawing of Earthing for S&T Installation 6 19-D6 Earthing Arrangements for Signals, Location Boxes 7 19-D7 Copper Plate Earthing Arrangement 8 19-D8 Full Location Wiring Format 9 19-D9 Half Location Wiring Format 10 19-D10 Signal Markers & Number Plates (10 Sheets) Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 414 of 530  Para No. 19.2.1 (b) (ii), 3.6.3 (d), 9.1.4 (b) (vi) Annexure: 19-A1 (Sheet 1 of 3) Form No.S&T/19.2.1/Signal sighting Signal Sighting Committee Report - For Shifting of Existing Signals/Erection of New Signals ………………….RAILWAY SIGNAL & TELECOMMUNICATION DEPARTMENT Name of the station:………………….., Division..…………………………………..., Name of Work.…………………………….., Signalling Plan Number: We, the undersigned members of the Signal Sighting Committee are aware of codal provisions on locating signals , read the guidelines in page 2 and conducted site survey on Dt ……….. and propose location of signals as given below as per our best judgment, the same are marked on enclosed drawing/Sketch. Is proposed signal from the adjacent Interference from provided if within adjacent Left side stop signal is on a improve visibility normal aspect of distance marked Action proposed drawing/Sketch) If infringing with from loco pilot’s Signal above rail is on LH side/RH proposed Signal proposed Signal Distance from a Arrow provided Is the proposed Implantation of implantation of Right side track If on RH side, is /Caution Board Signal from the Fixed structure Visibility of the Obstruction by Reason for the risky location* Fixed Lights (if Tree Branches to be taken to the proposed the Proposed Screen/Mesh If on RH side, point of view Height of the SOD, is the in Red Paint Description Signal no & 2 m of Live Is Visibility Conductor Adequate (mark on (Yes/No) (if any) same track level any) side (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (12) (13) (14) (15) Note: (i) Minimum visibility in MACLS territory: Distant signal: 400 meters, Stop signal: 200 meters. (ii) Placing a signal on RH side requires approval of competent authority. (iii) *Risky location is a location, where Train will stop on steep gradients/Girder Bridge/viaduct/Culvert/Cutting/Obstruction to Road/Theft prone area/ vicinity of chemical factories etc. Signature …………………….. Signature …………………….. Signature …………………….. Name & Designation ………………….. Name & Designation ………………….. Name & Designation ………………….. Date ………………………….. Date ………………………….. Date ………………………….. Drawing/Sketch showing proposed location of signals shall be enclosed duly signed by Committee members Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 415 of 530  Annexure: 19-A1 (Sheet 2 of 3) S. Guidelines for Signal Sighting - For shifting of existing Signals/erection of new Signals No 1 Factors to be considered for Locating a signal (a) Please refer to Para no: 7.1.13, 7.1.14 of SEM for placement of Signals. (b) A Stop signal shall be avoided (as far as possible) in risky location, where Train will stop on steep gradients/Girder Bridge/viaduct/Culvert/Cutting/Obstruction to Road/Theft prone area/vicinity of chemical factories. (c) Minimum visibility in MACLS territory: Distant signal: 400 meters, Stop signal: 200 meters. Please refer to Para no: 7.1.11. (d) Height of normal aspect of the Colour Light signal shall be approximately at 3.65 meter. (e) No external light shall dominate a signal aspect. If it cannot be resolved, proper screen shall be provided behind the signal unit to improve contrast. (f) Intermediate block signal shall be located, so as to split block section into near halves. It shall not be provided in a Block section with heavy and continuous falling gradients steeper than 1 in 80 unless the brake power of trains on the section is adequate to enable the trains being stopped at IB Signal. (g) Automatic signal shall be located normally with a spacing of one km from each other subject to other considerations and headway required. It shall not be provided in a Block section with heavy and continuous falling gradients steeper than 1 in 80 unless the brake power of trains on the section is adequate to enable the trains being stopped at each of the Automatic Stop Signals. (h) Any signal, if proposed on Right Hand side, requires prior approval of Competent authority. Right Hand signal shall be provided with a retro reflective type of arrow to indicate the line to which it pertains to. Note: (i) Till a signal is brought in to use, signal unit shall be turned away from direction of Traffic. No testing of signal aspects shall be done in the face of an approaching train, by turning signal towards direction of Traffic. (ii) when a signal is not in use, it shall be distinguished by two crossed bars (X) across it, each bar being not less than one metre long and 10 cm wide. (GR 3.18) (iii) Signals not in use shall not be lit. (GR3.18 (3)) (i) When signals are going to be in close proximity, they may be combined as per Para 7.1.16. (i) Under approved special instructions, a colour light Distant signal may be combined with the last Stop signal of a station in rear or with an Intermediate Block signal or with a Stop signal protecting a level crossing. (Ref: GR: 3.07(7) , G.S.R. 157(E).-Dated-05-3-21) (ii) Where proposed IB signal location and a mid section Gate are in proximity, IB signal shall be so located, to protect LC gate also. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 416 of 530  Annexure: 19-A1 (Sheet 3 of 3) 2 Schedule of dimension (SOD) - Considerations (a) Minimum horizontal distance from centre of the track (Implantation) to any structure as per schedule of dimension. Please refer Annexure: 19-A2 of SEM (b) Each signal post shall be marked with it`s Centre to centre (Implantation) distance to track/ Tracks in Black colour in white background for Normal Implantation and in Red colour with white background for reduced implantation. (c) If any signal post and/or any of it`s components are infringing with schedule of dimensions, such post shall be painted with alternate Red & white stripes at Loco Pilot`s eye level (3.65 m) and it`s Centre to centre distance to adjacent Track(s) shall be marked in red colour on a white background on the signal post itself, showing an arrow towards infringing track, for easy identification. 3 Precautions in RE area extract from ACTM para 16.4 to 16.5 of Appendix I (a) If any portion of a signal post or its fittings falls within 2 meters of a 25 KV live conductor, or any it`s metal part, such portion shall be protected by an iron screening solidly connected to the structure. If not, a Caution Board shall be provided on the signal post at a height of 3 meters above the rail level, to caution the staff. (b) Neutral section shall be located away from stop signals, level crossing. If neutral section is provided after a stop signal, the distance* between signal and neutral section shall be such that after stopping, the train shall be able to pick up enough speed to coast through the neutral section without any risk of stalling. If neutral section is provided before a stop signal, the distance* between neutral section and signal shall be such that the train shall not cross the signal in an effort to coast the neutral section. *Note: The distance should be preferably 1600 meter away on section with gradient up to 1 in 300 and 2500 meter with higher steeper gradient up to 1 in 200, if unavoidable. If PTFE type short neutral section has been used, this distance can be reduced to at least 400 meter after the stop signal and 200 meter before the stop signal. 4 Please also refer to Extracts of Para 20.5 of Appendix-1: Manual of AC Traction - Volume II (Part-II) for placement of signals in RE area, given at Annexure: 22-A1. 5 Any other stipulation as given by Railway Board & RDSO from time to time shall also be followed. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 417 of 530 Para no: 19.2.1 Annexure: 19-A2 Extract of Schedule of Dimensions (SOD) The minimum horizontal distance from centre of the track to any structure as per schedule of dimension (SOD) (addendum & corrigendum slip no (ACS) no 26 dated 10.1.2019) shall be as follows: New works or S. For existing From Level to Level alterations to No works existing works 1 From rail level to 305 mm above rail level 1675 mm 1905 mm 2 From 305 mm above rail level to 3355 mm 2135 mm 1905 mm increasing 3 From 305 mm above rail level to 1065 mm to 2360 mm 4 From 1065 mm above rail level to 3735 mm 2360 mm 2135 mm 5 From 3355 mm above rail level to 4115 mm decreasing to 1980 mm 2360 mm 6 From 3735 mm above rail level to 4420 mm decreasing to 2135 mm 2135 mm 7 From 4420 mm above rail level to 4610 mm decreasing to 1980 mm 8 From 4115 mm above rail level to 6250 mm 1600 mm 9 From 4610 mm above rail level to 6250 mm 1600 mm 10 Below rail level up to formation level of the track 2575 mm 2575 mm on straight and curves up to radius of 875 m 11 Below rail level up to formation level of the track 2725 mm 2725 mm on straight and curves with radius less than 875 m Note: Latest Amendments of SOD as issued from time to time shall be followed. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 418 of 530 Para No. 19.11.7(d) Annexure: 19-A3 Method for Finding Out the Resistance of an Earth The typical connection diagram used for measurement of earth resistance from ‘Fall of Potential’ method is given below: The earth resistance may be measured as per ‘fall of potential’ method using four terminal earth tester, as given below: (i) Connect Current probe C1 & Potential probe P1 to the earth electrode(s) under test. (ii) Drive a probe onto the earth 30 to 60 meter away from the earth electrode(s) under test and connect to terminal C2. In case of earthing system having multiple earth electrode like ring earth, the Current probe C2 should be in the direction which is away from the set of electrode(s) under test. This probe should be driven to a depth of 15 to 30 cm. (iii) Drive another probe onto the earth midway between the electrode(s) under test and probe C2. Connect this probe to terminal P2. This probe should also be driven to a depth of 15 to 30 cm. (iv) Measure the earth resistance. Say it is Reading 1. (v) Move the potential probe P2 by 3 meter farther away from the electrode(s) under test and do the earth measurement. Say it is Reading 2. (vi) Move the potential probe P2 by 3 meter (from midway) towards the earth electrode(s) under test as shown in figure above and do the third measurement of earth resistance. Say it is Reading 3. (vii) If all the three reading are within a few percent of their average, then average of the three readings may be taken as the earth resistance of electrode(s) under test. Note: In case there is a significant variation of three measurements from their average, then location of test probe C2 may be shifted to a farther distance and test may be repeated. Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 419 of 530