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Copyright © ATL Transformers Ltd 2019
Doc Ref TECH148 Issue 1
1. Isolate incoming supply, when isolated remove transformer lid and disconnect Input supply
and Secondary Output connections.
2. Using a calibrated 500V d.c insulation resistance tester check insulation resistance. Primary to
body (Earth) Secondary to body (Earth) & Primary to Secondary.
3. Check incoming supply voltage at protection, If within tolerance Isolate supply at the
protection and connect Incoming supply cables onto the respective transformer terminals.
4. Using a DVM and with the transformer energised, safely check at the output terminals
secondary tap voltages are within 2% using the tap selector to cycle transformer taps
accordingly. Check Secondary tap voltages which should be within 2% of the terminal voltage.
5. Isolate Supply and when safe re-connect Secondary Output cables.
6. Energise the transformer and using a calibrated ammeter check the load current.
Relevant safety checks & testing should be conducted in addition to these checks & in line with
Network Rails controlled safety & inspection procedures prior to energizing the transformer.
4.2 TESTING IN SERVICE
These units are non serviceable and require observational maintenance only to their Terminals,
cables and enclosure panels which must be intact and installed as originally supplied.
Always ensure that there is 100mm clearance around the transformer taking care not to
obstruct or impede on the transformers cooling louvres.
Do not place any foreign bodies on top of the enclosure lid or inside the transformer housing.
This does not supersede any maintenance tasks or scheduling procedures network rail deem
necessary and set in accordance with. NR/SP/SIG/10661 Signalling Maintenance Task Intervals.
Each unit is provided with a serial number and part code reference. This Information is located
on the transformer rating plate and should be quoted at any Point where the unit is examined
and suspected to be compromised.
4. PRODUCT MAINTENANCE
4.1 ROUTINE MAINTENANCE
