Sopers Lane, Poole, Dorset
BH17 7ER
Traffic Signal Junction Cabling
Design Certification for ELV Systems
Part no.
667/DS/20664/048
THIS DOCUMENT IS ELECTRONICALLY APPROVED
AND HELD IN THE TS DOCUMENT CONTROL TOOL
Issue Change Ref Date
1 First issue October 2007
2 TS006376 March 2012
3 TS006919 April 2013
Prepared By / Checked and ReleasedCompany/Dept. / Siemens Mobility, Traffic Solutions / Siemens Mobility, Traffic Solutions
Name / Dave Brocklehurst / David Martin
Function / Senior Product Engineer / Product Engineering Manager
Signature
Date / May 13 / May 13
COPYRIGHT STATEMENT
The information contained herein is the property of Siemens plc. and is supplied without liability for errors or omissions. No part may be reproduced or used except as authorised by contract or other written permission. The copyright and the foregoing restriction on reproduction and use extend to all media in which the information may be embodied
Copyright ã Siemens plc 2013 All Rights Reserved
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Document Name / 667-DS-20664-048 DBR2.DOC to highlight whole footer(s) and press F9. / Doc. No. / 667/DS/20664/048
/ Siemens Mobility, Traffic Solutions
Sopers Lane, Poole, Dorset
BH17 7ER
Siemens Mobility, Traffic Solutions,
Sopers Lane,
Poole,
Dorset,
BH17 7ER
SYSTEM/PROJECT/PRODUCT :
Site Reference:
Site Address:
Prepared By:
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This Document is fully issued when this page is at a FULL numeric issue and all of the following pages are at the same full numeric issue below and is either signed if provided in paper form, or has the name of the person preparing it added above by the person who has edited the detail / designed the junction cabling layout.
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This is a published work the copyright in which vests in Siemens plc. All rights reserved.
The information contained herein is the property of Siemens plc. and is supplied without liability for errors or omissions. No part may be reproduced or used except as authorised by contract or other written permission. The copyright and the foregoing restriction on reproduction and use extend to all media in which the information may be embodied.
CONTENTS
1 INTRODUCTION 4
1.1 Purpose 4
1.2 Scope 4
1.3 Related Documents 4
1.4 Glossary 4
1.5 Use 4
2 General NOTES ON INSTALLATION WIRING 4
2.1 Neutral Connections (Ground Returns ELV) 4
2.1.1 Introduction 4
2.1.2 Context 5
2.1.3 Procedure 5
3 Cabling 5
3.1 Cable Maximum Loading (Limited by the heating effect) 5
3.2 Loading limited by Cable Voltage Drop (thus associated with cable length) 6
4 ducting 11
4.1 Capacities 11
5 CABLE impedances 13
5.1 1mm2 Armoured Cable 14
5.2 1.5mm2 Armoured Cable 14
6 COMPLETION OF VERIFICATION CALCULATIONS 15
7 APPENDIX A Verification Calculations 16
8 APPENDIX B COMPLEX DUCTING CAPACITIES 18
LASt Page 19
Issue History
Site Reference Issue 3 Page 3
/ Siemens Mobility, Traffic SolutionsSopers Lane, Poole, Dorset
BH17 7ER
1 INTRODUCTION
1.1 Purpose
This document is intended to allow an assessment to be made on the suitability of the cabling design for an ELV traffic controlled junction installed by TS using TS provided cable. Providing all of the criteria noted in the subsequent sections and sub sections are complied with within the junction design, the cable and terminations design can be certified as complying with BS7671 and Electrical Installation Certificates signed off.
1.2 Scope
This document only applies to cables 998/4/70468 and 4/MC832 supplied by TS, and cable terminations supplied in TS traffic controllers and Pole Caps.
1.3 Related Documents
BS 7671 IEE wiring Regulations
667/SA/20664/000 Design and Manufacturer Supplied Information.
667/HE/20664/000 Installation and Commissioning Handbook
1.4 Glossary
ELV Extra Low Voltage
1.5 Use
The tables in the body of the document allow a quick check of the electrical design. For a more detailed check should one be required or if the values or extent of the tables are exceeded the calculation form in the appendix should be used.
The process is to edit the data in this document for the particular customer / site and then provide a paper or magnetic copy to the customer, who should then forward it on to the appropriate installing company. To edit the forms in the appendices of this document, you will need Microsoft Excel, double click on them and they will open up in Excel to allow editing. When you have edited the data, click back on the body of the main word document and the modified tables will be copied back to the word document. Then save the word document in the normal way. Please remember to edit the document series number picking a base number appropriate to your TS base i.e. DEPOT and selecting the next variant in order. The site reference must also be edited in the footer to ensure each page indicates the site for which it is relevant.
2 General NOTES ON INSTALLATION WIRING
The standard size of cable drum used in the field by TS is 250m; anything else is a special order.
TSs Recommendations are that ELV and detector cabling are run in separate ducts, where ever possible.
2.1 Neutral Connections (Ground Returns ELV)
For the purpose of the following text, for ELV systems the ground return is considered in the same way as a neutral return for a LV system.
2.1.1 Introduction
Street wiring faults can sometimes affect the display of traffic signals on-street. Poor connections, for example in pole top termination blocks usually leads to the failure of signals to illuminate properly which may be detected by lamp monitoring where this is implemented.
2.1.2 Context
Where common neutral connections are used it is possible for the failure of a neutral connection to cause unexpected signal displays, where one or more signals within a given signal head are incorrectly illuminated simultaneously. This lack of neutral connection is not detectable by the controller because the signal voltage presented at the controller terminals does not exceed the required thresholds for conflict or correspondence monitoring.
When incandescent signals are used a cable fault of this type usually causes the signals to be illuminated at a low level and is not particularly noticeable. For LED signals however it is possible for the signals to flash, at least at their 'dim' level. Although the rate of signal flashing is such that they are only typically illuminated for a very short time, less than the conflict / correspondence time defined in TR2500, it can be more noticeable than the display seen with incandescent lamps.
2.1.3 Procedure
Normally this type of fault only affects a single signal head or pole and due to other signals displaying correctly is unlikely to cause signalisations that could be considered dangerous, so retrospective action is not essential.
Therefore we are not mandating retrospective action on existing sites, however if the customer wishes to re-wire then we can do this on a chargeable basis
However for new LED sites where it is desired to reduce the likelihood of incorrect displays, particularly involving green signals, it is recommended that individual neutral returns are used for each green signal. For existing incandescent sites where LED signals are being now fitted and spare cables cores are available these may be used to provide additional neutral connections.
3 Cabling
3.1 Cable Maximum Loading (Limited by the heating effect)
The ST900 ELV LSLS card supplies and monitors up to 8 off ELV signal head aspects, 8 off LED Wait indicators, or 4 off TS Nearsides. The LSLS card can also supply 8 off Demand Indicators The HPU card supplies and monitors up to 8 off ELV Reg Signs. It is therefore not necessary to supply more than 8 off loads through one core, but the following information is shown for completeness.
The following is based upon the worst case with all cores carrying the specified current and the maximum number of any type of cable possible, i.e. the worst case condition (thus removing the need to calculate all scenarios),whilst also taking into account the controller maximum load per aspect drive. (See also LIMTS OF LOADING IMPOSED BY MAXIMUM DUCT CAPACITIES). Provided that the loading per core is kept below the maximum number of heads / maximum current value specified below, then the requirements of BS 7671 can be guaranteed. If loadings above these are required then Engineering at Poole should be consulted. This later is extremely unlikely.
LOADINGCore Size / Amps / ELV Reg Signs / ELV Signal Head Aspects / Red/Green Nearsides / LED Wait and Demand Indicators
1.00 mm2 / 3.5 / 24 / 14 / 9 / 24
1.50 mm2 / 4 / 27 / 16 / 10 / 27
3.2 Loading limited by Cable Voltage Drop (thus associated with cable length)
The ST900 ELV lamp loads are shown below, and will be used to calculate maximum cable lengths.
Bright 48VTS ELV Regulatory Sign / 7 W
TS Helios ELV (Vehicular or Far-Side Ped Signals) / 12 W
TS CLS Wait Indicator (for Far-Side Ped Signals) / 12 W
TS LED Wait Indicator (for Far-Side Ped Signals) / 7 W
TS Red/Green Nearside Signals / 18 W
TS Ped Demand Indicator (for Near-Side Signals) / 6 W
ST900 ELV Lamp Load (Watts)
When estimating cable core and controller equipment requirements for the ST900 ELV Controller the maximum cable lengths defined in the following tables must be complied with.
The voltage drop in the installation must be no more than 4% of the incoming supply. The tables should be consulted to ensure that the voltage drop is lower than this maximum for the selected core size and loading. If the voltage drop exceeds 4% the cores / conductors must be paralleled up to reduce it.
In addition the following guidance should be observed:
1. Where multiple cores are required due to long cable runs it must be noted that this may require additional LSLS Outputs (and possibly an additional LSLS Card) in order to accommodate the additional terminations in the LSLS Backplanes.
2. Where common ground return connections are used it is possible for the failure of a ground return connection to cause unexpected signal displays, where one or more signals within a given signal head are incorrectly illuminated simultaneously. This lack of ground return connection is not detectable by the controller because the signal voltage presented at the controller terminals does not exceed the required thresholds for conflict or correspondence monitoring.It is therefore recommended that individual ground returns are used for each green signal.
3. The allowable lamp load per cable run is defined in the following tables. Refer to the above table to determine the total lamp load connected to each drive cable and each return cable.
For each ‘out-going’ drive cable, determine the total load of all the signals supplied by that cable. This will typically be a single aspect (e.g. one Helios ELV signal) but could be higher where a green drive also powers a tactile unit for example.
A single LED signal return core (equivalent to the neutral in an LV system) is to be provided for each Red, Amber, Green Signal (or Nearside Red / Green Signal). Where a common return core is used, the highest lamp load that may be illuminated at any one time needs to be determined.
For a UK traffic signal head, one Helios ELV lamp load 12W is considered the highest for the return cable since only one aspect is ever illuminated; the short red/amber period is ignored.
For a near-side pedestrian signal head, the figure is one near-side signal unless it shares the same return with a Demand Indicator or a Tactile Unit.
Example, assuming a distance of 180 metres using 1.0mm2 cable:
· Near-side ped drive cables: 18W each at 180 metres = 2 cores (each)
· Ped demand indicator drive cable: 6W at 180 metres = 1 core
· Common return cable: 24W (6W+18W) at 180 metres = 3 cores
4. If required to minimise core usage it is permissible to common signal returns on the same pole as long as the total lamp load dependent on that return is considered and the cable length limitations defined in the table are observed. For example, two 12W RAG traffic signal heads require that a load of 24W is considered with a common return cable. (Note: please also consider the comments given in paragraph 2)
5. Regulatory signs should normally be cabled with a separate drive and return core.
Where more than one regulatory sign is fitted to a pole, the drive and return for these may be common, as long as total load dependent on those cables is considered and the cable length limitations defined in the table are observed.
If required to minimise core usage it is permissible to common regulatory sign and traffic signal returns on the same pole as long as the total load dependent on that return is considered and the cable length limitations defined in the table are observed.
Example, assuming a distance of 100 metres using 1.0mm2 cable:
· Reg Sign supply cable: 7W at 100 metres = 1 core
· RAG traffic signal drive cables: 12W at 100 metres = 1 core each (x3)
· Common return cable: 19W (12W+7W) at 100 metres = 1 core minimum but 2 cores recommended to allow an individual return for the green signal (see comments given in paragraph 2 ) .
It should be noted from looking at the table that above 100 metres, 2 cores would be required for the 19W common return, and above 160 metres, 2 cores would also be required for each 12W signal drive cable.