CH 22 Section 8 PDF

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...

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