Chapter 22: Requirements of Signalling in 25KV AC Electrified Area PDF

Chapter 22: Requirements of Signalling in 25 KV AC Electrified Area Section 1: General 22.1.1 Objectives (a) To ensure that signalling equipment continues to function normally in the presence of trac...

Chapter 22: Requirements of Signalling in 25 KV AC Electrified Area Section 1: General 22.1.1 Objectives (a) To ensure that signalling equipment continues to function normally in the presence of traction current. (b) To ensure that interference from the traction system cannot, under any circumstances, cause the Signalling system to exhibit false indications, or in any other way imperil the safe operation of trains. This objective must be achieved even if the traction or Signalling system is in a faulty or anomalous condition. (c) To safeguard equipment and staff from electric shock. 22.1.2 Factors Affecting Signalling in AC Electrified Area (a) Visibility of signals due to OHE structure. (b) Electrical clearances of signals due to live OHE close by. (c) Traction return current. (d) Electrostatic induction and Electro-magnetic Induction. 22.1.3 Visibility of Signals shall be taken care of by the proper implantation of OHE structures during the design stage of OHE. Where electrical clearances are not possible to maintain, suitable protective shields for signal structures shall be provided. Lay Out Plan for OHE shall be based on approved Signalling Plan. Note: (i) Protective wire-mesh screen of approved design and size shall be provided wherever clearance of more than 2 meter for any part of the signal from live OHE conductor is not possible to get. (ii) OHE bonds (Structural, longitudinal and cross bonds) to be provided by electrical department in the yard and in the block section wherever required for proper functioning of field S&T equipment. These bonds should be properly fastened with the structure/mast/rails and must be insulated for portion passing under positive rail of track circuit. 22.1.4 The electrostatic induction is practically eliminated by transferring a circuit into underground cables protected by a metal sheath. The Electro-magnetic Induction causes various currents and voltages to develop in conductors parallel to the track. These include the rails, traction return conductors where provided, cable sheath, any other conductors in the vicinity, and signalling and telecommunication circuits. The voltages that occur in the conductors appear as potential gradients. In addition, there are potential differences between various points along the conductors and the adjacent Earths. The value of this induced voltage depends on various factors, such as- Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 474 of 530  (a) Length of parallelism between the cable conductors and the electrified track. (b) Soil conductivity. (c) Screening efficiency of the cable sheath where existing. (d) Return current through the rails and return conductor where provided. (e) Mutual inductance between catenary and the cable conductors. (f) Separation between catenary and cable. (g) Current carried by the catenary etc. Section 2: Signal Structures in RE area 22.2.1 Colour light signals only shall be used in electrified areas. 22.2.2 On electrified sections, the masts, insulators, wires and supports obstruct the visibility of Signals. In addition, the Signals have to be so erected that they maintain a minimum clearance from the live parts of the O.H.E. The instructions in this section shall be strictly followed in so far as the electrical clearance is concerned. These instructions may be taken as a rough guide in determining the location of signals, which would afford the best visibility to the Loco Pilots of approaching trains. However, the actual visibility shall in all cases, be checked by a Signal Sighting Committee and action to improve the visibility taken on the recommendations of the Committee. 22.2.3 The location of signals and the protection required shall be worked out from the following signal clearance diagram for Broad gauge. Drg. No 22-D1 For Tangent tracks & tracks with super elevation less than 60 mm. Drg. No 22-D2 For Curved tracks with super elevation 60 mm to 140 mm. Drg. No 22-D3 For Curved tracks with super elevation 140 mm to 185 mm. 22.2.4 In these diagrams the un-shaded portion shown above the standard moving dimensions is the area into which a signal posts or any of its fittings shall, under no circumstances, be allowed to infringe. The shaded envelope around this is the area into which a signal or its fittings shall not normally be allowed to infringe. If due to unavoidable reasons, a portion of the signal post or its fittings has to infringe into this shaded area, special protective measures as detailed in para 22.2.6 shall be taken. The dotted outline in Drg. Nos. 22-D1, 22-D2, 22-D3 for Broad Gauge is applicable when there are two sets of Catenary and Contact wires parallel to each other in the same span, viz. insulated and un- insulated overlap locations. It is to be noted that these diagrams are not applicable to (i) anchor spans, (ii) turnouts, (iii) 3 meters on either side of masts, and (iv) in loco sheds and inspection pits. The diagrams are also not applicable when there is a feeder line running along with masts or where booster transformers and return conductors are provided. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 475 of 530 22.2.5 The normal height of the contact wire is 5.60 meters at supports. The normal height of the catenary at its highest point is 7.05 meters. In tunnels as well as underneath bridges, where clearances are limited, the contact wire may be as low as 4.58 meters for Broad Gauge and the catenary is also lowered suitably or terminated at the face of Bridges or Tunnels. The clearance diagrams have, however, been drawn to suit the extreme positions of the catenary and the contact wire. In addition, the diagrams make allowances for the stagger as well as displacement of wires by wind. 22.2.6 Clearances for Safety In the matter of electrical clearances, the fundamental rule to be observed is that no one is allowed, under normal conditions, to approach closer than 2 meters from the extreme positions of the live parts of the O.H.E. The following protective measures shall, therefore, be adopted. (a) If any portion of a signal post or its fittings where signalling staff have to work, falls within 2 meters of a 25 KV live conductor, or any metal part electrically connected to this conductor such portion shall as far as practicable be protected by an iron screening of approved design solidly connected to the structural work. (b) If for any reason it is not practicable to provide the protective iron screening as mentioned above, a Caution Board of approved design shall be provided on the signal post at a height of 3 meters above the rail level, to caution the signal staff. Note: Technical personnel shall exercise particular care to protect themselves while working on signal posts not provided with protective screens. If there is any likelihood of any part of their tools or equipment coming within 2 meter of live equipment, they shall take a power block as detailed in Chapter VI of the Manual of AC Traction-Volume II (Part-I). The same precautions are also required in the vicinity of return conductors, which should be treated as live. (c) The SSE/JE (Signal) shall explain these instructions to the staff working under them and ensure that they are correctly complied with. 22.2.7 Drg. Nos. 22-D4 and 22-D5 illustrate the location of signals on the left-hand side and right hand side of Broad Gauge track and the figures indicate the minimum heights and distances of Signal from the track to avoid electrical infringements. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 476 of 530 22.2.8 Location of Neutral Section (Reference: Para No. 16.4 to 16.5 of ACTM, Appendix I) Para Neutral section shall be located away from stop signals, level crossing and No. 16.4 shall be on tangent track and on level to the possible extent. Para If neutral section is provided after a stop signal, the distance* between signal and No. neutral section shall be such that after stopping, the train shall be able to pick up 16.4.1 enough speed to coast the neutral section without any risk of stalling. Para If neutral section is provided before a stop signal, the distance* between No. neutral section and signal shall be such that the train shall not cross the 16.4.2 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. The PTFE type short neutral section shall be located on level tangent track at least 400 m after the stop signal and 200 m before the stop signal. Where, however, modifications require to comply with these guide lines are difficult or entail heavy investment, the Chief Electrical Engineer of the Railway may direct any other arrangement to be followed consistent with safety and reliability, and for location on graded section according to para 16.4.1 and 16.4.2. (Para No. 16.4.5 of ACTM). Section 3: Erection of Signals in RE Area 22.3.1 Location of Signals in RE Area Normally, all signals should be located on the left side of the track for which it refers. In exceptional cases the signals may be located on the right side. To ensure adequate visibility of signals the OHE masts should be implanted as per the ACTM. In case it is not possible, offset brackets may be used for signal units without affecting the schedule of dimensions. Further the following steps should be taken to achieve adequate visibility. (a) In case the traction mast is located in front of the signal post, the distance between the traction mast and signal post should not be less than 30 meters. In addition, it should be ensured that no traction mast is located in advance of the signal post at a distance less than 10 meters. (b) PCSTEs and PCEEs of the zonal railways shall give dispensation for reduction in the distance of placing mast in front of the signal from 30 meters to 10 meters on straight track after ensuring staggering for proper visibility of signal as per provisions of ACTM and SEM. (c) The signal post should be sufficiently high so as to be seen clearly. (d) On tangent tracks it is desirable that the signal should be located within the OHE structure, i.e. the implantation of the signal from the track centre shall be less than the implantation of the OHE mast from the track centre. The setting of OHE masts in the vicinity of the colour light signals shall be as per para 20.5 of Appendix-I of the AC Traction Manual, Vol-II (Part-!I). Relevant extracts as in Annexure:22-A1. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 477 of 530  (e) On curved track or in areas, where other obstructions such as buildings, trees etc. exist, the site should be individually examined by the 'signal sighting committee' for deciding the most appropriate location of the signal. 22.3.2 No portion of a post or fittings of a colour light signal shall infringe with the schedule of dimensions from the centre line of the nearest track. 22.3.3 Signals without Junction Indicators Outside Tracks (a) Distance of OHE masts shall be in accordance with Drg. No.22-D6. (b) The signal units shall be so fixed that the height of the centre line of the red signal shall be approximately 3.65 meters above rail level. No part of Signal without a route indicator shall normally be higher than 5.2 meters above rail level. 22.3.4 Signals without Junction Indicators between Tracks (a) If signals are located between tracks no OHE structures shall be provided in the same track space for at least 600 meters in rear of the signals. (b) Portal drop arms shall not normally be located at least for a distance of 600 meters before the signal in track space where signals are located. (c) If a portal drop arm has to be unavoidably located in rear of signal itself, the signal shall be mounted on an offset bracket. In addition special study shall be made in each case to see whether the portal drop arm should also be offset from the centre line of the track space in the direction opposite to the offset of the signal. This special study shall be made for at least three portal drop arms in rear of the signal and shall also cover the possibility of shortening the portal drop arm. 22.3.5 Signals with Junction Indicators Outside Tracks Signals with Junction Indicators outside tracks Setting distances of OHE masts shall be in accordance with Drg.No.22-D7. 22.3.6 Signals with Junction Indicators between Tracks (a) Precautions and parameters for location of portal drop arms shall be as specified under Para 22.3.4. (b) For details of drawings, illustrating the above principles for Colour Light Signals, refer to Drg.No.22-D7. 22.3.7 The visibility of the signal shall be checked by day as well as by night by the Official in charge (Signal) of the section after each phase of the O.H.E work, i.e. erection of masts, provision of brackets, wiring, etc. If at any stage the official feels that the visibility is not adequate, he shall impose suitable speed restrictions and take such steps as are required to improve the visibility. Note: For Details on Cable laying in RE Area, please Refer to Chapter 15 of SEM. 22.3.8 For Clearances for Signals for High Rise OHE (for Running Double Stack Container & Three Tier Car) , Please see Annexure: 22-A3 and Drg.No.22-D7 Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 478 of 530  Section 4: Signaling Circuits in RE area 22.4.1 As a rule, no aerial circuits shall be retained in the electrified zone. In every case, the length of parallelism and the distance of Block Wires from the nearest electrified track shall be checked to ensure that the maximum induced voltage does not the exceed 60 volts limits prescribed by CCITT. 22.4.2 Barring block-instrument circuits, no other earth-return circuit shall be permitted in A.C electrified territory. Block instruments, however, shall be suitably protected by a filter of approved design as explained in Chapter 18 of SEM. 22.4.3 The following electrical signalling equipment are not safe to withstand AC induced voltage. The coils of this equipment can only be used inside a cabin or a location box or internal circuits only. The coils of these equipment shall be worked from a separate battery/DC-DC Converter and this battery/DC-DC Converter shall not be connected to any external circuits going outside the cabin/location box. (a) Luminous Indicators. (b) Telephone type relays. (c) Electrical Lever Locks. (d) Door Coil of IRS Block Instrument. (e) 250 Ohm D.C. neutral Line Relay. (f) Rotary Key Transmitter. (g) D.C. Neutral Polar Relays. 22.4.4 All Batteries and the wiring in the equipment, location box or cabin shall be well insulated from the ground. PVC insulated wires to an approved specification (IRS- S-76) shall be used for wiring in location boxes and cabins. 22.4.5 Separate Batteries/DC-DC Converters shall be provided for external and internal circuits. 22.4.6 When more than one cable is laid between two locations or cabins, it shall be ensured that as far as possible, all wires pertaining to any individual circuit are within the same cable. 22.4.7 Polarized Relays using permanent magnet shall not be used in any external circuit in 25 KV AC electrified areas as the permanent magnet in the relay tends to lose its magnetic properties due to continuous application of induced voltages. Competent authority shall authorise any exception in specific cases. 22.4.8 The relays, which release an interlocking, shall be slow acting so that the interlocking is not released inadvertently by voltage variations of short duration. Time delay may be of the order of 0.6 to 0.8 seconds. 22.4.9 All external circuits in AC. electrified area shall work with double cutting. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 479 of 530  Section 5: Outdoor Signalling Circuits in RE area 22.5.1 Maximum Length of Parallelism (a) The length of any signalling line circuit must be limited to ensure that the induced voltage from the traction system does not exceed 400 Volts under normal conditions. If necessary, line circuits must be sectionalized. Where line circuits leave line side enclosures or buildings in different directions, this could give rise to a continuous circuit of such length that the limits of induced voltage above could be exceeded. In such cases a sectionalized power supply unit should be provided for each direction. (b) The induced voltage in the underground-Unscreened cable shall be reckoned as 116 Volts/km on single line and 95 Volts/km on Double Line under normal conditions when the catenary current of 800 amperes for single line and 1000 amperes for double line. (c) When such circuits are terminated on relays/equipment their immunity shall not be less than 400 V AC. Length of feed cable terminated on relay shall be suitably reduced depending upon its AC immunity. (d) The length of DC Circuits on Line Relays with unscreened cable shall be restricted to- Type of Relay AC immunity Maximum permissible length on* level in volts Single Line Double Line QNA1/QNNA1/QNA1K 1000 2.1 km 2.8 km K50 B1 170 1.0 km 1.2 km K50 B1-A2 450 2.1 km 2.8 km K50 130 750 meters 900 meters AC Immunized neutral 750 2.1 km 2.8 km relay (IHC Make) * Maximum permissible induced voltage is restricted to 400 V for human safety and factor of safety 1.5 has been considered. Section 6: Signal Feed Circuitry in RE area 22.6.1 Feeding Distance Signal feed system shall be of the 110 V 50 Hz type or any approved type. 22.6.2 The distance between the signal control relays and the signal must not exceed the prescribed limits in electrified zone, measured along the line of way. This will ensure that the voltage induced in the circuit will be inadequate to illuminate the lamps, even under the most adverse circumstances and with one or more earth faults present. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 480 of 530 22.6.3 Maximum permitted length of direct feed of signal shall be as per Table given below. Type of Cable 110 Volts feed system Single Track Double Track Unscreened 180 m 220 m 22.6.4 When a signal is located at a distance greater than that specified in para 22.6.3 the signal shall be fed locally by controlling relays located at the location. Such signals may also be remotely fed from the cabin by using a controlling relay at the location. Typical circuit is given in Drg. No. 22-D9. 22.6.5 It shall be ensured that the power transformer for feeding circuits as per para 22.6.2 shall be different from the transformer feeding longer circuits. Section 7: Point Operation & Detection in RE area 22.7.1 Point can be operated electrically or mechanically by rodding. Mechanical operation of point will require special measures for the protection of operating staff. Electric operation shall have restriction on maximum length between point control relays and point machine depending upon their immunity level. 22.7.2 Electric Operation of Point (a) Point detection and point detection repeat circuits shall use ac-immunized relay. (b) The maximum permissible length for various types of commonly used Point Machines is as under: Maximum permissible parallelism in meters Type of AC immunity between Point Contactor and Point Motor Machine level in volts Single line Double line As per 160 910 1100 IRS S-24 400 2200 2800 Factor of safety is 1.5 (c) 3 phase point machine is inherently immune to induced voltage and therefore can be used for operating point to any length subject to its own operating limitation. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 481 of 530 22.7.3 Rod Runs in RE Areas The point rods in A.C electrified areas are subject to a certain amount of induced voltage. In addition since the rods are in contact with the rails at some point or other, the rail voltage, which can be quite high in case of faults, is transmitted through them to the lever frame. Insulators shall, therefore, be provided on the rodding as per instructions in para 22.7.4 for protecting the Operating & Maintenance Staff from the effects of these voltages. 22.7.4 Insulated Rod Joints for RE (a) The insulated rod joints shall be as per approved drawings. (b) Each rod shall be provided with an insulator in the lead out as close to the cabin as possible. While providing this insulator, it shall be ensured that there is no possibility of a contact between the insulated portion of one rod and the un-insulated portion of another rod or signal wires, the rail or O.H.E mast. (c) An additional insulator shall be provided between the last adjustable crank and the point or the lock bar. The purpose of this insulator is to prevent the rail voltage being passed on to the main run of rods. (d) If the distance between the two insulators at either end is greater than 300 meters, additional insulators shall be provided on each rod, so that the distance between two consecutive insulators on the same rod is not greater than 300 meters. (e) Each Point, Trap indicator and lock bar operated by rodding shall be electrically isolated from the track. (f) All insulators in a run shall be provided between the same two sets of rollers and guides, so that there is no possibility of the insulated portion of one rod coming into contact with the un-insulated portion of another rod. (g) The clearance between the insulator and the adjacent rod roller shall be adequate to permit normal movement of the rod. (h) When a rod crosses the track, the top of the rod shall not be less than 40 mm from the bottom of the rail. When steel or C.I sleepers are used, the distance between the rod and the sleeper shall be also not less than 40 mm. Similarly, the distance between any O.H.E mast and the point rods shall not be less than 40 mm. (i) The operating rod of locally worked points on all electrified lines and of similar points taking off from the non-electrified track adjacent to the last electrified line shall also be provided with an insulator so that the point lever or point box is insulated from the rail. (j) When the Engineering department provides the point lever or point box, Engineering department shall provide the insulator on the operating rod. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 482 of 530 22.7.5 (a) Please refer to SEM Chapter 16 for details of Power supply arrangements. (b) Please refer to SEM Chapter 17 for details of Track Circuits, AFTC in RE area, Axle counter. (c) Please refer to SEM Chapter 18, section 2 for details of Block working in RE area. (d) Please refer to SEM Chapter 19, section 11 for details of Earthing. Section 8: Rules for Protection of Staff working on Signal & Telecommunication Installation 22.8.1 Protection for Staff Railway personnel working on Signal & Telecommunication equipment on sections provided with 25 KV A.C traction are required to take suitable precautions on account of the following:- (a) Proximity to live conductors. (b) Presence of returns currents in the rails. (c) Induction in all metallic bodies situated near the overhead equipment. 22.8.2 Proximity of a Live Conductor: Any contact direct or indirect, with the 25 KV conductors is dangerous and shall be strictly avoided. 22.8.3 Pressure of Return Current in Rail The flow of return current in the rails will give rise to a potential difference. (a) Between adjacent rails at an insulated joint of a track circuit or at an ordinary joint in case the fish plates and bonding are broken. (b) Between the ends of a fractured rail at the fracture. (c) Between an insulated rail and the non-insulated rail used for the traction return current. (d) Between the rail and the surrounding mass of earth. 22.8.4 Wherever staff has to work on installations, which are in direct or indirect contact with the rails, they shall: (a) Insulated tools must be used in accordance with approved instructions. (b) Observe provisions of Section 'J' of permanent way manual (extract given at Annexure: 22-A2). Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 483 of 530 22.8.5 Induction in Metallic Bodies Situated Close to OHE Induced voltage may appear in Signalling and Telecommunication Circuits when the length of parallelism to the track is appreciable. Even if there is no induced voltage in a circuit at the time of starting a work, precautionary measures listed below shall be taken, as induced voltages may develop at any time on account of an increase in current in the traction lines. It is also to be noted that in the case of equipment or circuits, which are earthed, a contact, which may normally be without danger, may give rise to an electric shock in the case of a break in the circuit or in the earth connections. Consequently, when staff have to work on Signal and Telecommunication Circuits on 25 KV AC electrified lines, they shall take the following precautionary measures: (a) They shall as a general rule, wear rubber gloves and use tools with insulated handles. (b) When the work to be done is of such a nature that rubber gloves cannot be used conveniently, special precautions shall be taken by splitting the circuits into sections or earthing them. In special cases, both the steps shall be taken simultaneously. If these protective measures cannot be applied, staff must insulate themselves from the ground by using rubber mats, etc. (c) The cable conductors pertaining to the block instruments are likely to develop heavy induced voltages and every time the staff handles the terminals of Block Circuits, they must rigidly observe the provisions of paragraphs (a) and (b) above. These cable terminals shall be printed “RED” to remind the Maintenance staff of the danger. The Maintenance SSE/JE (Signal) shall explain the meaning of this painting to the maintenance staff and ensure that they correctly understand it. 22.8.6 Before any work is undertaken on Signalling/Telecommunication cables, the staff shall take the following precautionary measures: (a) Reduce the length of the circuit as much as possible. (b) Use Rubber gloves as far as possible or alternatively use insulated rubber mats. (c) Before cutting the armour or the metal sheath of the cable or the wires in the cables, an electrical connection of low resistance shall be established between the two parts of the armour, the Sheathing and wires that are to be separated by cutting. 22.8.7 Staff who have to work on electrical circuits shall be equipped with insulated tools such as box spanners, pliers, screw-drivers, etc. They shall, in addition, be supplied with rubber mats and rubber gloves. In regard to staff who have to work on equipment directly connected to the rails, tools with insulated handles may be supplied as far as possible and as far as practicable. A plastic sleeve on the handle will be sufficient in most cases. 22.8.8 Staff shall make themselves familiar with the instructions for treatment of persons suffering from electric shocks. Instruction Boards in English and in the regional languages describing the methods to be adopted for treatment of electric shock shall be clearly displayed in all SSEs/JEs (Signal)' offices. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 484 of 530 22.8.9 Breakage of Catenary/Contact Wire In the event of break of catenary/contact wire of the overhead electrical equipment, the following precautions shall be taken for the safe working of the signalling equipment: (a) The Train Controller, on receipt of an advice of a break in Traction Overhead Lines or confirmation of such an advice from the Traction Power Controller, shall immediately advise by the quickest possible means, to all the staff responsible for the maintenance and operation of the signalling equipment of the section where the catenary/contact wire has broken. (b) The staff responsible for the operation of the Signalling equipment of the section shall immediately check whether the block and other signalling equipment are working normally. If an abnormal working of any equipment is noticed, its working shall be immediately suspended and necessary action under the Rules shall be-taken. (c) On receipt of this intimation, the staff responsible for the maintenance of Signalling system of the section shall immediately proceed to the site and test all circuits and allied equipment paying particular attention to the external signalling gear to ensure that no damage to it has taken place. An authorised representative of the Signal Department not below the rank of SSE (Signal) shall submit Certificate that everything is working all right and send it to his superiors along with a detailed test report as soon as possible. 22.8.10 2.2 KV Charging as an Anti-Theft Measure (a) Guidelines for anti-theft charging pertaining to S&T works as prescribed in Appendix VII of ACTM Vol-II Part II shall be followed. (b) Besides, any specific works pertaining to specific section, the following S&T work shall be completed before issue of certificate for 2.2 KV charging. (i) Replacement of existing DC track relays and DC line relays by AC immunized relays. (ii) Provisions of wire mesh screen on the working platform of existing signals in case the requisite electrical working clearance of 2 meters is not available. No portion of signal post or its fittings shall be less than 700 mm from the live conductor. (iii) Supply of insulated tools to maintenance staff. (iv) Conversions of all overhead track crossings of BSNL and Railway into cables and removal of overhead wires thereof. (v) Certificate of clearance from DOT regarding 2.2 KV anti-theft energisation. 22.8.11 An approved checklist of the works to be completed as per provisions of this chapter shall be issued by Principal Chief Signal and Telecom Engineer to the field offices. Compliance of this checklist shall be insured by the nominated officers responsible for issue of certificate before OHE is charged at 25 KV. Note: Please refer to concerned chapters for specific requirements for any particular Type of equipment. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 485 of 530  Note : This Chapter has under mentioned Annexures S.No Annexure No Description 1 22-A1 Visibility of Signals in RE Area (Extracts of Para 20.5 of Appendix-1: Manual of AC Traction) 2 22-A2 Maintenance in Electrified areas (Extract of part 'J' of Permanent Way Manual) 3 22-A3 Clearances for Signals for High Rise OHE (for Running Double Stack Container & Three Tier Car) Vol. II (Part-II) This Chapter has under mentioned Drawings in Appendix II S. No Drawing No Description 1 22-D1 Signal Clearance Diagram to Suit 25 KV AC Traction for Tangent Tracks and Curved Tracks with S.E.60. 2 22-D2 Signal Clearance Diagram to Suit 25 KV AC Traction for Curved Tracks with 60 to 140 S.E. 3 22-D3 Signal Clearance Diagram to Suit 25 KV AC Traction for Curved Tracks with 140 to 185 S.E. 4 22-D4 Colour Light Signal Left Hand or Right Hand Broad Guage (Tangent Track). 5 22-D5 Colour Light Signal with Junction Route Indicator Left Hand or Right Hand Broad Gauge (Tangent Track). 6 22-D6 Distance in Rear from the Signal in Meters (Sheets 2). 7 22-D7 Distance in Rear from the Signal in Meters for High Rise OHE (Sheets 2). 8 22-D8 Implantation of OHE Structures with respect to Colour Light Signal. 9 22-D9 Signalling Feed Arrangement with Cut-In Relays. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 486 of 530 Para No. 22.3.1(d) Annexure: 22-A1 Visibility of Signals in RE Area (Extracts of Para 20.5 of Appendix-1: Manual of AC Traction - Volume II (Part-II) 20.5 Masts near Signals: The visibility of signal should be kept in mind while deciding the setting up masts in their vicinity. The following principles should be observed for deciding the setting of masts near signals. 20.5.1 Colour light signals located outside all tracks. (a) Colour Light Signals without Route Indicators: (i) Where no approach signal is provided: The minimum settings of mast before should be 3.25, 3.10,3.05,2.90 and 2.75 m for distance up to 80m, beyond and up to 110m, beyond and up to 190 m, beyond and up to 270 m and beyond and up to 400m respectively. (ii) Where approach signal is provided and for signals other than distant signals: The minimum setting of masts before the signal should be 3.25, 3.10, 3.05, 2.90 and 2.75 m for distance up to 50 m, beyond and up to 70 m, beyond and up to 115 m, beyond and up to 160 m and beyond and up to 240 m respectively. (b) Colour Light Signal with Route Indicators: (i) With Horizontal Route Indicator: The minimum setting of masts before the signal should be 3.72, 3.50, 3.25, 3.05, 2.90 and 2.75 m for distances up to 60 m, beyond and up to 125 m, beyond and up to 170 m, beyond and up to 215, beyond and up to 250 m, beyond and up to 310 m respectively. (ii) With other than Horizontal Route Indicator: The minimum setting of masts before the signal should be 3.50, 3.25, 3.05, 2.90 and 2.75 m for distance up to 70 m, beyond and up to 130 m, beyond and up to 170 m, beyond and up to 215 m and beyond and up to 280 m respectively. Note: 1. See Drg. No. ETI/OHE/G/00112 also. The setting may be reduced in special cases, conforming to Figs. 6 to 9 of ibid. 2. Setting distance may be reduced for starter signals of loop lines and yard lines. 20.5.2 Colour Light Signals Located Between Tracks (a) Signals without Route Indicators: No OHE mast should, as far as possible be located in the same lane as the signal for a distance of at least 600 m before a signal. Drop arms of portals should also not normally be located in the lane where signals are located at least for a distance of 600 m before the signal. Where this is not possible, for any reason, the signal should be mounted on an off-set bracket. In addition, a special study should be made in each such case in respect of three drop arms before the signal, to see whether the drop arms can be off-set from the center line of the lane in a direction opposite to the off-set of the signal or alternatively, whether it is possible to shorten the drop arms. Reduction in the signal's height may also be examined. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 487 of 530 (b) Signals with Route Indicators: The principles mentioned under para 20.5.2 (a) should be observed in these case also. Note: 1. No. part of a colour light signal without a route indicator should, as far as possible be higher than 5.2 m above rail level. Great care should be exercised in deciding the locations of colour light signals with route indicators so that the necessary minimum clearances are available between the signals and live out of run conductors, or pantogaphs way zone. 2. On signal-line sections, signals (colour light as well as semaphore) should, as far as possible be located on the side of the track opposite to the OHE masts. 20.5.3 For semaphore signals located outside the track: The minimum settings of masts before the signal should be 3.05, 2.90 and 2.75 meters for the first, second and next three masts respectively. Note: For details see Drg. No. ETI/OHE/G/00112. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 488 of 530 Para No. 22.8.4(b) Annexure: 22-A2 Maintenance in Electrified Areas (Extract of part 'J' of Permanent Way Manual PART 'J') 282 General Instructions to Staff: - 1) General Knowledge of Engineering Staff (a) Every Engineering official working in electrical traction area shall be in possession of a copy of rules framed for the purpose of the operation of the Traction Power Distributions System pertaining to Engineering Department and ensure that staff working under him are also acquainted with the rules. He will ensure that rules pertaining to carrying out engineering works are strictly observed. (b) All electrical equipment, every power line or cable shall be regarded as being 'live' at all times. No work shall be commenced adjacent to any electrical equipment except on authority issued in writing by a competent official of the Electrical Department to the effect that the equipment has been made dead and earthed. 2) Defects in Overhead Equipment: Defects or break downs in the overhead equipment including track and structure bonds noticed by the Engineering staff shall be reported immediately to the Traction Power Controller. When defects in the overhead equipment that are likely to cause damage to pantographs or trains are noticed, and it is not possible to convey information to Station Masters or Signal men to enable them to issue caution orders, the line shall be protected by the staff noticing such defects according to General Rule 3.62. 3) Traction Bonds: In electrified areas the return current fully or partially flows through the rail. To ensure a reliable electrical circuit continuity and also to ensure proper earthing in case of leakage of current, various types of traction bonds as described below are provided at suitable places and maintained by the Electrical Traction Department: - (a) Longitudinal Rail Bonds: In the case of D.C. traction system, practically the whole return current flows through the rail. Therefore, two flexible copper bonds offering minimum resistance to the flow of current are provided at each rail joint under the fishplates. Two solid lugs at the two ends of the copper bonds are inserted in holes drilled at the two rail ends between the fish bolt holes and are pressed by using a bend press to rivet them firmly to the rails. On points and crossings and at junction fishplates where continuity bonds of the above type cannot be provided due to space constraints, continuity of return current path is achieved by using mild steel straps or G.I. wire ropes. Absence of such bonds may cause unsafe working condition and in extreme cases may damage the rail ends. (b) Cross Bonds (D.C): Cross bonds are provided between adjacent tracks at regular intervals to reduce resistance of the current to the minimum. Such cross bonds are also known as transverse bonds. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 489 of 530  (c) Structure Bonds: All structures supporting overhead equipment either in AC or D.C. track circuited areas are connected to the running rails for ensuring good earthing. Failure of insulator or leakage of current switches off the supply from the sub station so that men coming in contact with supporting structure etc., do not get electric shock. Removal or tampering of such bonds can, therefore, result in unsafe conditions. Since the structure are grouted in concrete, they are likely to become charged in case such bonds are kept disconnected. Similarly, other steel structures such as foot-over bridges, sheds, etc., in the vicinity of O.H.E lines are also connected to rails through similar structure bonds. 283 Special Instructions to Staff working in Traction area: 1) Need for Precautions: Precautions are required to be taken on account of following: (a) Proximity of a Live Conductor: The risk of direct contact with live O.H.E is ever present while working in electrified sections such as for painting of steel work of through spans of bridges and platform cover. (b) Build up of Potential due to Return Current in Rails: The return current in the rails may cause a potential difference: (i) Between rail and the surrounding mass of earth; (ii) Between two ends of a fractured rail; (iii) Between the two rails at an insulated joint; & (iv) Between earth and any other metallic mass. 2) The following precautions should, therefore, be taken while working in traction areas: - (a) No work shall be done within a distance of two meters from the live parts of the O.H.E without a 'permit-to-work'. (b) For work adjacent to overhead equipment the Engineering Inspect or shall apply to the proper authority sufficiently in advance for sanctioning the traffic and power block required. The Traction Power Controller through Traction Foreman will arrange to isolate and earth the section concerned on the date and at the time specified in consultation with the Traffic Controller. He shall then issue 'Permit-to-work' to the Engineering Inspector. On completion of the work the' Perm it-to-work' should be cancelled and Traction Power Controller advised, who will then arrange to remove the Earth and restore Power supply. (c) No part of a tree shall be nearer than 4 meters from the nearest live conductor. Any tree or branches likely to fall on live conductors should be cut or trimmed periodically to maintain this clearance. Authorized O.H.E staff should do cutting or trimming. (d) No fallen wire or wires should be touched unless power is switched off and the wire or wires suitably earthed. In case the wires drop at a level crossing, the Gatekeeper shall immediately make arrangements to stop all road traffic. (e) Work on Station Roofs and Signal Gantries: Staff working on station roofs and signal gantries and similar structures adjacent to live Overhead Equipment shall not use any measuring tapes, tools and materials when there is a possibility of their being dropped or carried by wind on to the live overhead equipment. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 490 of 530 (f) Earth Work: For excavation work adjacent to tracks, the following action is taken:- (i) In D.C. traction areas, intimation should be given in writing sufficiently in advance to the concerned Traction Distribution Officer to enable him to depute the Traction Staff to be present in order to prevent possible damage in the traction underground feeder cables which are always located near the running lines. (ii) In AC traction areas, intimation should be given to the concerned officers of the Electrical General Services and also S&T Department, since all the S&T and Electrical lines are cabled on account of Electrical Induction. In all AC and D.C. traction areas, the Traction Department provides cable markers showing location of cables. In addition, tiles and bricks protect the cables and during excavation, if workmen come across such tiles or bricks in an arranged manner, they should at once report the matter to the higher officials. Any further excavation should be carried out only in the presence of the authorized staff of Electrical Traction and or S&T Department as the case may be. (g) The relative alignments of the centerline of the track with respect to the alignment of the contact wire must be maintained within the specified tolerances. This applies to both horizontal and vertical clearances. Slewing or lifting of track must not be done outside the agreed maintenance limits unless the position of the contact wire is altered at the same time. Adjustment of cant has a magnified effect on the horizontal displacement of the centerline of the track with respect to the alignment of the contact wire. Horizontal clearances to structures within the limits laid down in the Schedule of Dimensions must be maintained. For slewing or alterations to track involving adjustment of contact wire (outside the agreed maintenance limits) sufficient notice should be given to the traction staff so that that they arrange to adjust the overhead equipment. (h) Alterations to Track Bonding: All bonds removed by the staff of the Engineering Department shall be replaced by the staff of the Engineering Department and all such removals and replacements shall be reported to the Assistant Electrical Engineer, Traction Distribution in charge, concerned without delay. (j) Working of Cranes: No crane shall be worked except on the authorized 'permit-to- work'. In every case of working of a crane, arrangement should be made for the presence of authorised overhead equipment staff to ensure that all safety precautions are taken. (k) Inspection of Tunnels: For inspection of roofs and sides of a tunnel, the overhead equipment shall be rendered 'dead'. Special insulated apparatus should be used if sounding the unlined portions to locate loose rock in the roof and sides, is required to be carried out, when the overhead equipment is 'live'. (I) As far as possible closed wagons shall be used for material trains. In case open or hopper wagons are used, loading and unloading of such wagons in electrified tracks shall be done under the supervision of an Engineering official not below the rank of a Permanent Way Mistry, who shall personally ensure that no tool or any part of body of the worker comes within the' danger zone', i.e. within 2 meters of OHE. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 491 of 530  (m) Steel tapes or metallic tapes with woven metal reinforcement should not be used in electrified tracks. Linen tapes are safer and, therefore, should be used even though they are not accurate. (n) The top of foundation blocks in electrified structures should be kept clear of all materials. 284 Maintaining Continuity of Track: 1) During maintenance or renewal of track, continuity of the rails serving electrified tracks shall invariably be maintained. For bridging gaps, which may be caused during removal of fish-plates or rails, temporary metallic jumpers of approved design shall be provided as under. The Electrical Department on requisition will provide the necessary jumper. 2) In case of rail fracture, the two ends of the fractured rail shall be first temporary connected by a temporary metallic jumper of approved design (as shown in the sketch below). In all cases of discontinuity of rails, the two parts of the rail shall not be touched with bare hands; Gloves of approved quality shall be used. 3) In the case of track renewals temporary connection shall be made as showed above. 4) In the case of defective or broken rail bond, a temporary connection shall be made as shown above. 5) Before fishplates are loosened or removed temporary connections shall be made as in sub section (3) above. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 492 of 530 285 Catch Sidings: Normally all catch sidings except those, which are sanded, shall be kept alive. On sanded catch siding, the rails shall be kept clear of sand for a length of 21.5 meters, beyond the section insulators in the overhead lines and the switches controlling the sanded catch sidings shall be kept in the neutral position. If an electric engine or single or multiple unit train runs into the sanded length of a catch siding, it may possible be insulated from earth except through the buffers or couplings if connected to other vehicles, therefore, these sidings shall not be made alive when an electric engine or single or multiple unit train or any vehicle coupled thereto are standing in the sanded track until all staff have been moved away from positions where they are likely to make contact between the permanent way formation and any part of the locomotive or single or multiple unit train or coupled vehicles. No person shall attempt to enter, or leave or in any other way make contact between the permanent way formation and the electric engine or single or multiple unit train or any vehicles coupled thereto while one overhead equipment of the sanded length of siding is alive. 286 Additional Precautions in AC Traction Area: The following additional precautions are required to be taken in AC traction areas:- 1) Build-up of potential due to induction in metallic bodies situated close to O.H.E : - It is important to note that dangerous voltage may be induced in metallic masses such as fencing posts in the vicinity of traction conductors. To avoid possibility of shock due to such voltages, the metallic structures are bonded together and earthed. 2) Unloading of Rails: When unloading rails along tracks, care shall be taken to ensure that rails do not touch each other to form a continuous metallic mass of length greater than 300 meters. 3) Permanent way staff are advised to keep clear of the tracks and avoid contact with the rails when an electrically hauled train is within 250 meters. 287 Fire in Electrified Areas: The Permanent Way Officials noticing a fire likely to result in loss of life or cause damage to property shall take all possible steps to prevent it from spreading and to extinguish it. In case the fire is on adjacent to any electrified equipment, the permanent way official shall make no attempt to extinguish the fire but shall report the occurrence of fire to the nearest Station Master by most expeditious means. 288 Permanent Way Tools: Permanent Way tools (insulated and un-insulated) along with gloves shall be used in the manner as approved by the Chief Engineer of the Railway. 289 Treatment of Persons Suffering from Electric Shock: When persons receive electric shock, practically in every case, they can be revived with the prompt application of First Aid. Method of Resuscitation: The method of resuscitation resorted to should be that known as artificial respiration. Continuity of Treatment: The efforts to restore breathing must be continued regularly and with perseverance, and must not be discontinued until a Doctor has taken charge of the case. 290 Accident to Power Lines of Outside Bodies: The Engineering Inspector shall be in possession of the name and address of the officer-in-charge of each power line across Railway land to enable an immediate report of any defect or accident appertaining thereto being made, under advise to the Assistant Engineer/Divisional Engineer. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 493 of 530 Para No: 22.3.8 Annexure: 22-A3 Clearances for Signals for High Rise OHE (For Running Double Stack Container & Three Tier Car) (Extract of Design Handout for High Rise OHE Document No: TI/designs/OHE/2014/00001 (Rev-1) issued by Traction Installation Directorate/RDSO) 7.5.1 COLOUR LIGHT SIGNALS LOCATED OUTSIDE ALL TRACKS (a) COLOUR LIGHT SIGNALS WITHOUT ROUTE INDICATORS (i) Where no approach Signal is provided The minimum setting distance of structure before the signal shall be 3.55, 3.40, 3.35, 3.20 & 3.05 m for distance upto 80 m, beyond & up to 110 m, beyond & upto 190 m, beyond & upto 270 m and beyond & up to 400 m respectively. (ii) Where approach Signal is provided and for Signals other than Distant Signals The minimum setting distance of structures before the Signal should be 3.55, 3.40, 3.25, 3.10 and 3.05 m for distance upto 50 m, beyond & upto 70 m, beyond & upto 115 m, beyond & upto 160 m and beyond & upto 240 m respectively. (b) COLOUR LIGHT SIGNALS WITH ROUTE INDICATORS (i) With Horizontal Route Indicator The minimum setting distance of structure before the Signal shall be 4.02, 3.80, 3.55, 3.35, 3.20 and 3.05 m for distance upto 60 m, beyond & upto 125 m, beyond & upto 170 m, beyond & upto 215 m and beyond & upto 250 m and beyond and upto 310 m respectively. (ii) With other than Horizontal Route Indicator The minimum setting distance of structures before the Signals shall be 3.80, 3.55, 3.35, 3.20 and 3.05 m for distance upto 70 m, beyond & upto 130 m, beyond & upto 170 m and beyond & upto 215 m and beyond & upto 280 m respectively. Setting distance may be reduced for Starter Signals of loop lines and yard lines. The setting distance can be reduced in special cases, conforming to Figures 6 to 9 of Revised RDSO Drawing No. ETI/OHE/G/00112, Revision ‘D’ or latest. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 494 of 530 7.5.2 COLOUR LIGHT SIGNALS LOCATED BETWEEN TRACKS (a) SIGNALS WITHOUT ROUTE INDICATORS No overhead equipment structure shall, as far as possible, be located in the same lane as Signals for a distance of atleast 600 m before a Signal. Drop Arms of Portals shall also not normally be located in the lane where Signals are located atleast for a distance of 600 m before the Signal. Where this is not possible for any reason, the Signal shall be mounted on an Offset Bracket. In addition, a special study shall be made in each such case, in respect of these Drop Arms before the Signal, to see whether the Drop Arms can be offset from the centre line of the lane in a direction opposite to the Arms. Reduction in the Signal height must also be examined. (b) SIGNALS WITH ROUTE INDICATORS The principles mentioned in the preceding paras shall be observed in this case also. No part of a colour light Signal without a Route Indicator, shall, as far as possible, be higher than 5.2 m above rail level. Great care must be exercised in deciding the location of the colour light Signals with Route Indicators so that the necessary minimum clearances are available between the Signals and live out of run wires, or pantograph sway zone. Note:- For Drawing on Distance in Rear from the Signal in Meters for High Rise OHE , Please refer to Drg.No: 22-D7 in Appendix II. Chapter 22: Requirements Of Signalling In 25 KV AC Electrified Area Page 495 of 530