Specifications
Siemens Mobility, Traffic Solutions
Sopers Lane, Poole, Dorset
BH17 7ER
Version 10 Page 108 of 120 Status Issued
Last Editor harry.smyth Date 03 November 2014
Document
Name
GENERAL HANDBOOK FOR HEIMDALL
DETECTORS
Doc. No.
667/HB/31900/000
Copyright Siemens plc 2014 All Rights Reserved
10 POWER SUPPLIES AND CABLE REQUIREMENTS
10.1 Heimdall Detector Power Supply Options
The Heimdall detector may be powered by a nominal 24 volts ac or dc supply and either
method may be employed depending upon circumstances.
The Heimdall detector power supply voltage should be within +20% of its nominal value,
i.e. 19.2v to 28.8v dc or ac RMS, and should not be more than 29 volts under any
circumstances.
The power supply requirements for the Heimdall detectors are listed in the appropriate
detector specification, Section 5.
10.2 Controller Power Supply Options
10.2.1 24V DC Supply
In general Siemens controllers are equipped with a 24 volt dc supply which is available
for a small number of detectors. This supply may be used providing there is sufficient
spare current capacity.
10.2.2 24V AC Supply – LV (Standard) Traffic Controllers
If the DC controller supply capacity is insufficient then an additional 24v ac voltage supply
may be added.
The standard Siemens part numbers of the controller mounted AC Detector Supply kits
are:-
Nominal 50 VA, (2 amps):- 667/1/27853/000
Nominal 160 VA, (6.6amps):- 667/1/20292/008
The kit contains a transformer, fusing and termination facilities.
The output of the transformer is nominally 25 volts but it will drop if the mains voltage falls
to the legal minimum (207 volts, which is -10% on the standard European voltage of 230v
or -13.75% on the standard UK voltage of 240v). Further voltage drops will occur due to
the loading of the transformer, the initial tolerance of the transformer and the resistance
of the cable.
Section 11, details the appropriate look-up tables for these transformers.
For more eccentric installations or non-standard transformer installation, section 12
details the appropriate method for calculating the appropriate cable lengths.