Siemens ST950 - ST950 ELV System Components; Lamp Supply Transformer

Mobility, Intelligent Traffic Systems
Sopers Lane, Poole, Dorset, BH17 7ER
Security classification
Unrestricted
Page
25 of 154
Version
7
Status
Issued
Last Editor
manpreet.jeerh
Date
January 2020
Document Name
ST950 ICM Handbook
Document No.
667/HE/45950/000
Copyright © Siemens plc 2020. All Rights Reserved. Mobility is a division of Siemens Plc
4 ST950 ELV SYSTEM COMPONENTS
This section details the main components of the ST950 ELV system.
4.1 Lamp Supply Transformer
The Lamp Supply transformer provides the high current 48V supply to the ELV
signal heads and a separate lower current 48V supply for Regulatory Signs. It
additionally provides a low voltage AC supply for the operation of the LSLS card
logic and a 24V DC supply for powering Loop Detectors, above ground detectors
and the solar cell.
The ELV transformer has two separate primary windings, so that it can be
configured for either 220/230/240V/250V operation or for 110/120V operation.
Issue 3 (and lower) Lamp Transformer has primary taps for
220/230/240V operation and 110/120V operation
Issue 4 (and higher) Lamp Transformer has an additional primary tap for
250V operation
Figure 6 to Figure 11 below show the terminations for the issue 4 Lamp
Transformer
4.1.1 Procedure for selecting transformer connections:
With a suitable multimeter set to read AC volts, measure the incoming mains supply
voltage and select the transformer tapping according to the table below:
Measured Voltage
Select Transformer Tapping:
245V to 276V
250V (see Note above)
235V to 244V
240V
225V to 234V
230V
187V to 224V
220V
115V to 138V
120V
94V to 115V
110V
Table 1 – Lamp Transformer Tappings
For a nominal 230V supply, if the measured voltage is below 196V or
above 253V, then advice should be sought from the local electricity
supplier
Connections to the transformer are made in accordance with Figure 6 to Figure 11