Sounds straightforward enough you might think, but there was no technical detail on the original transformer and, in fact, in the past someone had started to strip the transformer so some parts were missing. From photos and physical size, they were able to offer a couple of options in terms of rating. Although not a part of the signalling, Network Rail wanted any transformer to comply with the new Power Transformer Specification NR/L2/SIG/30007 in addition to the usual BS EN 60076 transformer standard. From the initial quotation to the consultant based on their standard build and enclosure, a number of modifications were made in consultation with the site electrical and mechanical engineers and project managers to incorporate a Switch Disconnector on primary side of the transformer and a suitable rated Moulded Case Circuit Breaker on the secondary side.
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In addition, due to access restrictions on site, terminal chambers were incorporated in the ends of the enclosure and an additional Earth terminal placed in the secondary terminal chamber with removable copper link to the secondary neutral to allow earthing of the secondary winding to a local earth. In addition, the enclosure was then finished in a light grey paint finish to match other local equipments. Some 10 weeks after the initial enquiry was made, and 6 weeks after the placing of the contract the 100kVA three phase transformer was delivered to the site at Cannon Street Station. Majestic Transformer Co have been manufacturing single phase transformers and three phase transformers, along with chokes and transformer rectifier power supplies for over 65 years and have a wealth of experience in manufacturing custom built transformers to meet many varied specifications and standards, from basic commercial & marine, to medical, railways & defence.
For further information visit: www.transformers.uk.com
(CD/KMcA)
