Transformers & Rectifiers - DC Traction Power Supplies and Auxiliary Power Transformers

Transformers & Rectifiers Ltd, part of the T&R Group founded in 1951, specialises in the design, engineering and manufacture of electrical power supply equipment for a variety of applications in industrial, medical, dockyard, power generation and transport areas.

The T&R Groups' diverse product range includes transformers, power rectifiers, voltage regulating transformers, engine driven generating sets, high voltage and heavy current test equipment and specialist welding alloys and consumables.

In 1998 T&R Ltd acquired the property rights to manufacture products previously made by Allenwest Brentford Ltd and Brentford Electric Ltd, who were prominent in the manufacture of traction power supplies and voltage regulator units.

QUALITY POWER TRANSFORMERS AND RECTIFIERS FOR RAIL APPLICATIONS

We manufacture both transformers and rectifiers in-house which we feel gives us greater control over product quality and compatibility. T&R Ltd has third party quality certification to BS EN ISO 9001:2000.

LIQUID-FILLED AND AIR-COOLED TRANSFORMERS AND REACTORS

We manufacture a wide range of equipment specifically designed to meet our customers' specifications. Our product range includes:

• Liquid-filled transformers and reactors up to 7.5MVA and 36KV
• Dry type air cooled transformers and reactors up to 4MVA and 24KV
• Power DC rectifier equipment up to 30KV and 30KA rating
• Small transformers and reactors for OEMs
• Brentford" voltage regulating transformers and regulating units up to several MVA throughput

POWER SUPPLIES FOR DC TRACTION

One of our specialist areas is in the manufacture of transformer rectifier units (TRUs) and auxiliary transformers for DC traction systems - either heavy traction or light rail. Recent DC traction schemes to use our transformer rectifier units include:

• Blackpool Tram (UK) – 500kW, 550VDC
• Croydon Tramlink (UK) – 600kW and 1,000kW, 750VDC
• Railtrack - North London Line (UK) – 2,000kW and 3,000kW, 750VDC
• London Docklands Light Railway - Lewisham Extension (UK) – 2,000kW, 750VDC
• Railtrack - Euston to Watford Line (UK) – 2000kW, 750VDC
• MTRC - Tseung Kwan O Extension, Hong Kong (HK) - 4,000kW, 1,500VDC
• Rail Link Engineering (RLE) - Channel Tunnel Rail Link (UK) – 3,000kW, 750VDC
• MTRC – Penny's Bay Line (HK) – 4,000kW, 1,500VDC
• Network Rail – Southern Region Power Supply Upgrade (UK) – 3,000kW and 4,000kW, 750VDC

TRANSFORMER RECTIFIER ARRANGEMENTS

Rectifiers for DC traction normally employ twelve-pulse rectification with either series or parallel bridge arrangements. The rectifiers are normally naturally air cooled with either 'fused' or 'fuseless' designs manufactured to order.

The rectifier transformer can be dry type or liquid filled, using mineral oil or synthetic liquid, for indoor or outdoor location. For twelve-pulse rectifiers two secondary windings are employed, normally arranged as one Delta and one Star connected.

There are in some instances, particularly for underground substations, stringent requirements to meet rigorous flame and smoke emission standards. T&R have the solution and have worked with London Underground Scientific Services Division to produce equipment that is compliant with LUL fire risk specifications.

OTHER T&R GROUP COMPANIES:

• T&R Generators Ltd for engine driven generating sets up to 2,000KVA
• T&R Test Equipment Ltd for high voltage and heavy current electrical test and relay test equipment
• T&R Welding Products Ltd for specialist welding alloys and consumables

All of the T&R Group companies are situated in Guildford, Surrey, England, which is readily accessed from the M25 London orbital motorway, central London and the London Airports of Gatwick and Heathrow.