Guidance on Signalling and Safety-Related Telecommunications Power Supplies and Circuits

Transcription

1 Railway Group Guidance Note Guidance on Signalling and Safety-Related Telecommunications Power Supplies and Signatures removed from electronic version Submitted by Synopsis This document provides guidance on meeting the requirements of Railway Group Standard GI/RT7017. Brian Bashford Project Manager Content approved by Multifunctional Subject Committee held on 12 May 2004 comprising representatives from the following subject committees: Train Control and Communications Subject Committee Plant Subject Committee Electrification Subject Committee Authorised by Anne Blakeney Acting Department Head Railway Group Standards Management Copyright in the Railway Group Standards is owned by Rail Safety and Standards Board Limited. All rights are hereby reserved. No Railway Group Standard (in whole or in part) may be reproduced, stored in a retrieval system, or transmitted, in any form or means, without the prior written permission of Rail Safety and Standards Board Limited, or as expressly permitted by law. In circumstances where Rail Safety and Standards Board Limited has granted a particular person or organisation permission to copy extracts from Railway Group Standards, Rail Safety and Standards Board Limited accepts no responsibility for, and excludes all liability in connection with, the use of such extracts, or any claims arising therefrom. This disclaimer applies to all forms of media in which extracts from Railway Group Standards may be reproduced. Published by: Rail Safety and Standards Board Evergreen House 160 Euston Road London NW1 2DX Copyright 2004 Rail Safety and Standards Board Limited

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3 Railway Group Guidance Note Page 1 of 18 Contents Section Description Page Part A A1 Issue record 2 A2 Implementation of this document 2 A3 Responsibilities 2 A4 Health and safety responsibilities 2 A5 Supply 2 Part B B1 Purpose 3 B2 Application of this document 3 B3 Definitions 3 B4 Principles 5 B5 Performance requirements 5 B6 Records 9 B7 Protection of signalling and safety-related telecommunications circuits 9 B8 Power supply restoration 11 B9 Personnel safety 11 B10 Identification 12 Figures 1 4 Demarcation between power supply systems and functional circuits 14 References 18 RAIL SAFETY AND STANDARDS BOARD 1

4 Railway Group Guidance Note Page 2 of 18 Document to be withdrawn as of 05/03/2011 A1 Issue record Part A Issue Date Comments One August 2004 Original document This document will be updated when necessary by distribution of a complete replacement. A2 Implementation of this document The publication date of this document is 7 August This document does not supersede any other RSSB Guidance Notes. A3 Responsibilities Railway Group Guidance Notes are non-mandatory documents providing helpful information relating to the control of hazards and often set out a suggested approach, which may be appropriate for Railway Group* members to follow. * The Railway Group comprises Network Rail Infrastructure Limited, Rail Safety and Standards Board Limited, and the train and station operators who hold Railway Safety Cases for operation on or related to infrastructure controlled by Network Rail Infrastructure Limited. Network Rail Infrastructure Limited is also known as Network Rail. Rail Safety and Standards Board Limited is also known as RSSB. A4 Health and safety responsibilities A5 Supply Each Railway Group member is reminded of the need to consider its own responsibilities to ensure health and safety at work and its own duties under health and safety legislation. RSSB does not warrant that compliance with all or any documents published by RSSB is sufficient in itself to ensure safe systems of work or operation or to satisfy such responsibilities or duties. Controlled and uncontrolled copies of this document may be obtained from the Corporate Communications Dept, Rail Safety and Standards Board, Evergreen House, 160 Euston Road, London NW1 2DX, telephone or enquiries@rssb.co.uk. Railway Group Standards can also be viewed at 2 RAIL SAFETY AND STANDARDS BOARD

5 Railway Group Guidance Note Page 3 of 18 B1 Purpose Part B This document provides guidance on meeting the requirements of Railway Group Standard GI/RT7017. Boxed extracts from the Railway Group Standard GI/RT7017 are included followed by guidance on the requirements. Where no guidance is provided for a specific section this is stated. B2 Application of this document B2.1 To whom the guidance applies This document contains guidance that is applicable to duty holders of the infrastructure controller category of Railway Safety Case. B3 Definitions Designed load The maximum load on a distribution main when all functional circuits that can operate simultaneously are in use. Distribution main A current-carrying circuit, containing no functional logic, from a source of supply to one or more equipment housings forming part of the power supply distribution system. Earth The conductive mass of the earth, whose electric potential at any point is conventionally taken as zero. The impedance to earth from equipment at a particular site may vary due to local ground conditions. Earth electrode A conductor, or group of conductors, in intimate contact with, and providing an electrical connection to, earth. Enclosure For the purposes of this document the immediate surround of electrical equipment provided for protection against direct contact with live conductors. Equipotential bond An electrical connection putting various exposed conductive parts and extraneous conductive parts at a substantially equal potential. This is sometimes abbreviated to bond or bonding. Exposed conductive part A conductive part of equipment which can be touched and which is not a live part but which has the potential to become live under fault conditions. External circuit A functional signalling circuit that extends, for example in cable, along the lineside between housings or other signalling or operational telecommunications equipment. entirely between housings that are located adjacent to each other are included in the definition of internal circuit. Fault A circuit condition in which current flows through an abnormal or unintended path, which may result from an insulation failure or bridging of insulation. Functional signalling circuit A circuit containing functional logic that operates signalling equipment or repeats its state to the controlling signalling centre. RAIL SAFETY AND STANDARDS BOARD 3

6 Railway Group Guidance Note Page 4 of 18 Document to be withdrawn as of 05/03/2011 Functional supply point Functional supply point, for the purposes of this document, is the point that the power supply distribution system connects with an item of supplied equipment. Housing A building, permanent or relocatable, apparatus case or other structure containing electrical equipment. Internal circuit A functional signalling circuit that is contained entirely within a single housing or between housings that are adjacent to each other. Power supply distribution system A system consisting of one or more distribution mains conveying power from a connection or connections with public supplies or private supplies to the functional supply point at the supplied equipment. Private supplies A power supply derived from a private source such as a generator or railwayowned high voltage distribution system, not subject to the requirements of the Electricity Safety, Quality and Continuity Regulations Public supplies A power supply provided from a network, subject to the regulation imposed by the Electricity Safety, Quality and Continuity Regulations Ring main For the purposes of this document a distribution main connecting a supply to a number of equipment housings by two paths in the form of a ring. The currentcarrying conductors are each rated to carry the total load of the whole ring. Safety management and information system The safety management and information system (SMIS), also known as the improved safety management and information system (ISMIS), is a national IT system used by all Railway Group members with legislation mandating its use. It is a database of all safety incidents and accidents occurring on Network Rail controlled infrastructure or within the Network Rail Safety Case. Safety-related telecommunications Telecommunications equipment or systems in operational use that have the potential to materially reduce the likelihood of risk to the safety of trains or personnel. Service failure (power supply) Service failure, for the purposes of this document, is a loss of power supply that results in a signalling failure. Signalling equipment Apparatus installed for the control and protection of trains and trackside personnel, including, but not limited to, point operation and proving, signals, train detection equipment, interlockings and signal box equipment. Signalling failure An interruption to the normal working of signalling equipment or systems resulting in a loss of, or incorrect, functionality sufficient to warrant an entry in SMIS. Supplied equipment For the purposes of this document, supplied equipment includes any piece of signalling equipment or safety-related telecommunications equipment, including power supply equipment where this contains safety-critical functions. (Such functions include polarity or phase of the power supply where this is safety critical.) Other defined terms are set out in GK/GN RAIL SAFETY AND STANDARDS BOARD

7 Railway Group Guidance Note Page 5 of 18 B4 Principles There is no guidance associated with this section. The following definitions apply to this Guidance Note: Double cut The insertion of relay or other contacts into both legs of a circuit, so as to provide enhanced protection against mal-operation due to earth faults. Single cut The insertion of relay or other contacts into one leg only of a circuit. B4.1 Railway Safety Principles and Guidance This document supports the following safety principles described in Her Majesty s Railway Inspectorate Railway Safety Principles and Guidance: Principle 20: The signalling system should provide for the safe routeing, spacing and control of trains. Principle 21: The signalling system should continue to provide for the safe passage of trains permitted to run under degraded conditions. B4.2 Statutory instruments This document supports the following statutory instruments: a) The Electricity at Work Regulations 1989 b) The Electrical Equipment (Safety) Regulations 1994 c) The Electricity Safety, Quality and Continuity Regulations B5 Performance requirements There is no guidance associated with this section. B5.1 Quality For each functional supply point, the infrastructure controller shall define and document the requirements for the power supply at the designed load. The requirements defined shall ensure the correct and safe operation of that equipment and shall include tolerances on each parameter. Parameters to be defined shall take into account the operational and safety needs of the system and shall include but not be limited to: a) supply voltage b) frequency c) current rating d) harmonic content e) the magnitude and duration of any spikes, noise or other perturbations on the power supply f) power factor g) inrush current. The infrastructure controller shall ensure that the power supply distribution RAIL SAFETY AND STANDARDS BOARD 5

8 Railway Group Guidance Note Page 6 of 18 Document to be withdrawn as of 05/03/2011 system is designed in accordance with the above requirements. When sourced from a public supply, the standard limits on the supply are defined by the Electricity Safety, Quality and Continuity Regulations 2002 which sets the limits as: a) Voltage: +10% -6% (based upon a nominal of 230 V phase voltage) b) Frequency: ±1% ( Hz). The National Grid Code allows for a range of Hz under exceptional circumstances. The infrastructure controller should ensure that the limits of voltage and frequency generated by emergency diesel generators and uninterruptible power supplies (UPS) are such that operational and occupational safety is not compromised. An example is the overspeeding of a standby generator causing synchronous timers to operate more quickly. The requirements, as defined at the functional supply point, should allow for additional voltage drop in the signalling or safety-related telecommunications functional power supply distribution system. The voltage drop at the extremities of distribution mains should be such to achieve the required parameters at the functional supply point under the final designed load, that is, the load applied when all of the equipment scheduled to be connected to the main is in full operation after final commissioning of the installation. The voltage drop at the extremity of the signalling power supply distribution system should not typically be greater than 10% of the supply voltage calculated or measured at the full designed load of the distribution main. Similar considerations should apply to the extremities of a ring main that is capable of being broken at any point. It is accepted that the supply voltage at each terminal on a distribution main that is capable of being fed from each end or is in the form of a ring main cannot be accurately regulated in all circumstances. Where equipment such as point machines are fed direct from the distribution main, it is acceptable to arrange for their sequential operation, so as to limit the design load. Overcurrent protective devices should be rated to take account of inrush current and other transients. B5.2 Availability The infrastructure controller shall define and document the required level of availability for the power supply to signalling and safety-related telecommunications at the functional supply point, consistent with the characteristics of the railway and its traffic. Equipment and systems shall be configured to minimise the effect of interruption of power to the supplied equipment. The infrastructure controller shall ensure that the power supply distribution system is designed in accordance with the above requirements. When assessing the availability of a power supply, it is necessary to consider the system as a whole, including the power supply, the equipment supplied and the overall configuration. One or more of the following arrangements should be employed, as specified by the infrastructure controller, according to the strategic requirements of the installation: 6 RAIL SAFETY AND STANDARDS BOARD

9 Railway Group Guidance Note Page 7 of 18 a) an alternative supply with provision to maintain the supply without interruption for the duration of the outage, for example, by the provision of UPS. Where UPS is specified, the infrastructure controller should state the maximum duration of power outage to be bridged by the UPS b) provision to limit the duration of an interruption to the supply, for example, by the provision of alternative sources of power, with an automatic changeover device c) provision to limit the duration of an interruption to the supply, for example, by the provision of alternative sources of power, but without an automatic changeover device d) provision for the temporary connection of an alternative source of power e) no provision for an alternative source of power. The design of the power supply feeding arrangements should be such as to limit the extent of a failure to an operationally logical area of railway, for example, by providing separate distribution mains for fast and slow lines. Faults at the extremities of long distribution mains, with cables reducing in size, may not in all instances pass sufficient current to operate the overcurrent device at the feed end. The system should be designed to allow for the detection and clearance of all credible fault conditions, for example, by the use of intermediate overcurrent protective devices. Ring mains should be installed where considered beneficial. Where ring mains are installed, switching facilities should be provided to open the ring at places specified by the infrastructure controller to enable faulty sections to be isolated. All sections of the ring main should be rated for the full designed load current of the whole ring. The source of external supplies should be assessed to ensure that they are satisfactory. This is because supplies incorporating residual current devices (RCDs), whilst offering an increased level of personal safety, possess an inherently reduced reliability and should be avoided unless the system design incorporates a means for maintaining the supply, for example, batteries or UPS. B5.3 Maintainability Equipment and systems shall be designed to enable maintenance and testing to be undertaken and configured without interruption of power to the supplied equipment unless it is demonstrated that it is not practicable to do so. The infrastructure controller shall ensure that the allocation of responsibility for maintaining parts of the system does not result in the failure to adequately maintain the complete system. Where very high levels of availability are required, power supply distribution systems should be designed to enable their component parts, including any automatic changeover facilities, to be tested whilst maintaining a supply to the supplied equipment. The only part of the system that might need to be disconnected for testing should be that which directly feeds functional signalling circuits. Measures to control risk during live working are addressed in clause B9.1 of the standard. Where responsibility for design, installation and/or maintenance is divided between several organisations or companies, the infrastructure controller should prepare a plan or method statement to ensure that the component parts, RAIL SAFETY AND STANDARDS BOARD 7

10 Railway Group Guidance Note Page 8 of 18 Document to be withdrawn as of 05/03/2011 including particularly the interfaces, are adequately maintained to ensure their functionality as a complete system. Consideration should be given to adapting the rules of the route to permit maintenance to be carried out. B5.4 Electrical testing B5.4.1 Power supply distribution system Facilities to aid fault-finding and testing of components of the power supply distribution system shall be included in the design. It is permissible for some or all of such testing to be undertaken from a remote location. The inspection and testing regime set out in BS 7671, or an equivalent standard, shall be applied to the power supply distribution system. Examples of facilities include the provision of test points, installed measuring equipment and monitoring equipment. The maintenance plan should allow for the full testing of alternative power sources and generators, including a simulated failure of the normal power source. B5.4.2 Extent of testing When developing the plan for testing of the power supply distribution system, the infrastructure controller shall take account of the effect on train running requirements. The testing requirements and their periodicity shall be determined, taking account of the following factors: a) the occupational safety of staff working thereon b) the operational safety of train movements c) the diversity of protection systems and equipment. The extent and periodicity of testing and any supporting assessment results shall be documented. The infrastructure controller shall ensure that this plan is adhered to whenever testing takes place. Testing of power supply systems should be programmed to take place at times of light traffic density. Consideration should be given to adapting the rules of the route to permit testing to be carried out. Unless UPS or other arrangements are in place to ensure continuity of supply to functional equipment, testing of changeover arrangements should assume that a short interruption of power to supplied equipment will occur. The infrastructure controller should make provision for the periodic inspection and/or testing of: a) equipotential bonding b) earth electrodes c) protective diodes, surge arrestors and spark gaps d) busbars of supplies not having earth fault detection e) earth fault detectors f) live circuits, as required by fault-finding and maintenance procedures g) cables 8 RAIL SAFETY AND STANDARDS BOARD

11 Railway Group Guidance Note Page 9 of 18 h) circuit breakers and other protective switchgear. B5.5 Environment The infrastructure controller shall specify the particular environmental requirements set out in BS EN with which each power supply distribution system shall comply. BS EN 50125, Part 2, outlines performance requirements for environmental conditions for fixed electrical installations. Part 3 deals similarly with signalling and telecommunications equipment. B5.6 Security of equipment The infrastructure controller shall establish the location, construction and security of signalling and safety-related telecommunications power supply equipment, including all associated cabling, to minimise the likelihood of criminal damage or unintentional disturbance to the extent commensurate with the application. There is no guidance associated with this section. B6 Records The infrastructure controller shall create and retain design records for new installations and modifications to existing installations that shall include but not be limited to: a) wiring diagrams b) cable and equipment ratings c) protection device ratings and discrimination d) distribution e) layout plan f) supply characteristics of private and public power supplies g) maintenance and test records. Consideration should be given to the retrospective application of this measure in respect of existing installations that have high availability targets. Appropriate records should be provided on site to aid maintenance and fault finding. RAIL SAFETY AND STANDARDS BOARD 9

12 Railway Group Guidance Note Page 10 of 18 Document to be withdrawn as of 05/03/2011 B7 Protection of signalling and safety-related telecommunications circuits B7.1 Safety-critical functional signalling circuits Safety-critical functional signalling circuits shall be resistant to high-risk failures, due to false operation as a result of: a) power supply interruption and restoration b) single or double earth faults. A reduced level of protection from earth faults is permissible where an assessment of possible failure modes of all such interconnected circuits indicates that this does not result in an increased risk to train operations. Functional signalling circuits should be designed to be free of earth and of earth reference. Exceptions arise where power supplies to electronic equipment, for example, train describers, are required to be earth referenced for technical reasons, but the earth-referenced supply is electrically isolated from all associated earth-free supplies. Methods available to achieve immunity to false operation due to earth faults include: a) double cutting of circuits b) the use of earth fault detection devices c) the use of electrically isolated power supplies d) insulation monitoring. Examples of existing applications where a reduced level of protection (single cutting) has been applied, include: e) first filament failure indication circuits (if sufficient contacts cannot reasonably be provided) f) signal lighting circuits and circuits where any credible earth fault would not cause a high-risk signalling failure g) internal circuits, fed from a supply that is internal within the same housing h) circuits that are otherwise protected, for example, by being suitably coded. Functional signalling circuit protection should usually be provided in one pole of the circuit, except in areas of conductor rail electrification where it is permissible to provide protection in both poles. Functional signalling circuits are commonly powered by any or all of the following supplies: i) 120 volt d.c. for point operation j) 110 volt a.c. for signals and general use k) 50 volt d.c. for relay circuits l) 24 volt a.c. for panel indications 10 RAIL SAFETY AND STANDARDS BOARD

13 Railway Group Guidance Note Page 11 of 18 m) 24 volt d.c. for level crossing equipment. The infrastructure controller should make provision for the periodic inspection and testing of: n) busbars of supplies not having earth fault detection o) earth fault detectors. B7.2 Telecommunications circuits Where telecommunications circuits share a supply with functional signalling circuits that are required to be earth free, the earth reference shall be electrically isolated from the signalling supply. There is no guidance associated with this section. B7.3 Earth fault detection Earth fault detection or insulation monitoring systems shall be provided for safetycritical functional circuits, together with arrangements for monitoring on a regular basis, on a scale commensurate with the level of risk involved. (See clause B2.5 for an exclusion for modifications to existing installations.) Conductors of functional signalling circuits are commonly designed to be free of earth and of earth reference. An exception is where power supplies to electronic equipment are required to be earth referenced for technical reasons, but the earth-referenced supply should be electrically isolated from all associated earthfree supplies. The use of separate supplies, for example, for point operation and detection functions, could serve to reduce the level of risk and hence the need for insulation monitoring. B7.4 Surge arrestors The infrastructure controller shall determine a policy for the application of surge arrestors, taking account of: a) the environment in which they are used b) their effect on train operations c) the effects of equipment failure due to surges (if surge arrestors were not provided). There is no guidance associated with this section. B8 Power supply restoration The infrastructure controller shall specify and document measures for the restoration of power supplies following a failure. The restoration of power supplies should be accomplished in a manner that: a) causes no risk of high-risk signalling failure b) avoids damage to equipment due to inrush currents c) avoids overloading due to excessive initial loading. RAIL SAFETY AND STANDARDS BOARD 11

14 Railway Group Guidance Note Page 12 of 18 Document to be withdrawn as of 05/03/2011 B9 Personnel safety B9.1 Safe system of work The infrastructure controller shall develop, maintain and document safe systems of work for personnel working on power supply systems and equipment. The installation shall comply with the accessible and touch voltage limits set out in BS EN Work on live equipment, including testing or the taking of measurements, should be subject to risk assessment, including consideration of the risk to personnel during the live working. This should include, for example, consideration of what personal protective equipment is, or needs to be, provided and the effects of wet conditions underfoot. The provisions of HSG85 should be followed as far as they apply. B9.2 Maximum length of functional circuits The maximum length of functional circuits shall be as specified by the infrastructure controller, in order to maintain occupational safety. In ac and dual ac/dc electrified areas and elsewhere, for example where the railway is paralleled by high voltage overhead transmission lines, the risk arising from shock due to induced longitudinal voltage in functional circuits shall be taken into account in the determination of functional circuit length. Unless otherwise specified by the infrastructure controller, in ac and dual ac/dc electrified areas, the maximum linear length of functional signalling circuits fed by a single power source, without the imposition of an isolating transformer, should not exceed 2 km in length. However, the design of the overhead line equipment system affects the induced longitudinal voltage, and the maximum limit should be agreed with the electrification system designer for each particular electrification scheme. Due allowance for future changes to the electrification parameters during the lifetime of the equipment should be made. This topic is addressed in a paper to the IRSE Aspect 2003 conference (see References). B9.3 Staff competency The infrastructure controller shall ensure that personnel who are required to work on signalling power systems or equipment possess the competencies required by GK/RT0101 and GO/RT3260 or a defined and documented equivalent level of competence. B10 Identification There is no guidance associated with this section. B10.1 Power supply equipment In addition to the requirements of the Electrical Equipment (Safety) Regulations 1994, the name and/or function of all items of power supply equipment, including switchgear, shall be clearly and permanently identifiable. All power sources shall be labelled as such and referenced in information provided for fire brigade personnel. The identification should include, for example, voltage, frequency, current rating. It should be contained on a plate or label that should also state the manufacturer s name and year of manufacture. 12 RAIL SAFETY AND STANDARDS BOARD

15 Railway Group Guidance Note Page 13 of 18 The name and/or function of equipment that is designed for ease of changing, for example, plug-in units, should be given on a separate label fixed adjacent to, but not attached to, the item. Where the isolation of the incoming supplie(s) does not render the whole installation dead, the presence and rating of all remaining sources of power should be identified on maintenance or other records that are made available to fire brigade personnel. Examples include UPS and point batteries. B10.2 Cable terminations All power supply cable terminations shall be clearly and permanently identified. Polarity shall be identified at any point where cables can be disconnected for maintenance, fault finding or renewal purposes. B10.3 Cables All power supply cables shall be clearly and permanently identified. B10.4 Busbars All busbars and each circuit outlet on the busbar shall be clearly and permanently identified. Where a distribution main conveys power to a number of equipment housings, the direction from which power can be fed shall be clearly indicated at each equipment housing. Busbars associated with reconfigurable feeders and ring mains shall be labelled with a warning that power can be fed in either direction. It is particularly important that cables, terminations and busbars should be clearly labelled with polarity or phase, to ensure that signalling or safety-related telecommunications functional circuits do not cause failures due to incorrect connection with the power supply. RAIL SAFETY AND STANDARDS BOARD 13

16 Railway Group Guidance Note Page 14 of 18 Document to be withdrawn as of 05/03/2011 Public Supply Grid Supply Private Supply Distribution Network Operator Supply Generator G Traction Derived Signalling Power Supply Distribution System Functional Supply Point Other Loads Supplied Equipment External Internal Circuit Figure 1: Demarcation between power supply systems and functional circuits 14 RAIL SAFETY AND STANDARDS BOARD

17 Railway Group Guidance Note Page 15 of 18 Overhead Line Equipment Distribution Network Operator Principal Supply Point UPS BS 7671 Functional Supply Point 400/110 V Figure 2: Demarcation between power supply systems and functional circuits (cont d) RAIL SAFETY AND STANDARDS BOARD 15

18 Railway Group Guidance Note Page 16 of 18 Document to be withdrawn as of 05/03/2011 REB Distribution Network Operator 240V Distribution Board Charger/Battery 50V Telephone Exch Main Distribution Frame Lineside cable Power Supply Distribution Functional Supply Point 50V Functional Signalling/ Telecomms Case Bonded to Traction Earth Figure 3: Demarcation between power supply systems and functional circuits (cont d) 16 RAIL SAFETY AND STANDARDS BOARD

19 Railway Group Guidance Note Page 17 of 18 Signaller's VDU Distribution Board 240V 240V UPS Functional Supply Point Figure 4: Demarcation between power supply systems and functional circuits (cont d) RAIL SAFETY AND STANDARDS BOARD 17

20 Railway Group Guidance Note Page 18 of 18 Document to be withdrawn as of 05/03/2011 GE/RT8015 GI/GN7607 GI/RT7007 GI/RT7017 GK/GN0802 GK/GN0806 GK/RT0101 GK/RT0206 GO/RT3260 References Railway Group Standards and other Railway Group Documents Electromagnetic Compatibility between Railway Infrastructure and Trains Guidance for Low Voltage Electrical Installations Low Voltage Electrical Installations Signalling and Safety-Related Glossary of Signalling terms Guidance Note: Signalling and Operational Telecommunications Systems: Safety Requirements Competence Standards for Signalling and Telecommunications Staff Signalling and Operational Telecommunications Systems: Safety Requirements Competence Management for Safety-Critical Staff The Catalogue of Railway Group Standards and the Railway Group Standards CD-ROM give the current issue number and status of documents published by RSSB. This information is also available from Other References BS 7671 Requirements for Electrical Installations (IEE Wiring Regulations) BS EN Railway applications Fixed installations Electrical supply and earthing systems for public transport BS EN Railway applications Environmental conditions for equipment Part 2: Fixed electrical installations Part 3: Equipment for signalling and telecommunications HSG85 Electricity at work: Safe working practices HSG153 Railway Safety Principles and Guidance Proc. IRSE (Aspect 2003) White R. Induced Longitudinal Voltage into Lineside Cables for WCRM S.I. 1989/635 The Electricity at Work Regulations 1989 S.I. 1994/3260 The Electrical Equipment (Safety) Regulations 1994 S.I. 2002/2665 The Electricity Safety, Quality and Continuity Regulations RAIL SAFETY AND STANDARDS BOARD