Radian TRC

Welcome to Radian TRC

We are specialist power transformer manufacturers. If you are looking for further information on Rectifier Transformers, AC & DC Furnace Transformers, Convertor Transformers or Distribution Transformers please contact us.


We focus in the range of 1 MVA to 20 MVA, and will consider ratings outside of that range. Typically our customers require HV voltages in the 3.3 kV to 33 kV range, though we can offer higher values.

We also offer high current reactors in steel core and air core varieties and high current, high voltage range transductors (saturable reactors) , typically for diode rectifier applications.

We are developing a compact, integrated rectiformer (rectifier transformer and rectifier) using a diode rectifier and transductor control. The unit is aimed at our customers requiring a simple robust solution for electrolysis-based processes.

Rectifier Transformers

Rectifier transformers cover a large number of configurations. The IEC60076 standard lists 19 configurations. Many of these were developed in the era of mercury-arc rectifiers and has less relevance since the development of high current thyristors (silicon controlled rectifiers) and more advanced devices such as GTOs and IGCTs.

Typical Configurations

Two rectifier configurations are commonly used, namely the common 3 phase bridge rectifier and a 6 phase double star with inter-phase transformer (IPT) which requires a dual secondary winding transformer design. The normal bridge rectifier uses a normal 3 phase transformer design.

We offer extended delta, phase shifted transformers where impedance and voltage matching is critical in a twelve pulse (12P) plant.

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Furnace Transformers

The smelting industry uses an AC or DC process depending on the Arc Furnace application. DC Electric Arc Furnace (EAF) transformers are similar in design to rectifier transformers, but have many more taps and on-load tap-changers. AC EAF transformers are subject to repeated short circuit conditions, and require a far more conservative design approach. They too typically have many taps and on-load tap-changers. AC EAF transformers are very often built as single phase units which allows the furnace design and process to be optimised. Tapping arrangements can become quite complicated depending on the voltage range and curve required.

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Converter Transformers

Convertor transformers are optimised for to supply variable speed drives (VSD) for motor control. A VSD typically injects a whole spectrum of harmonics into the supply lines, and the transformer design needs to accommodate these harmonics.

A convertor transformer is typically rated at 100% capacity where a distribution transformer is typically rated at 80% capacity. VSD drives are based on power electronics and usually require a neutral line, hence the most common vector group is Dyn11, that is a delta primary with a star secondary with the neutral point brought out.

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Distribution Transformers

Distribution transformers are type of which most people are aware. They range from small pole-mounted units to large units in distribution yards and substations. Typically robust oil-natural, air natural (ONAN) cooling is used due to the remoteness of the installation site and added complexity of other cooling options.

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Standard Range

Our standard range of distribution transformers follows SABS 780.

630 800 1000 1250 1600 2000 2500 3150

We will manufacture non-standard ratings and voltages to customer specification.

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Transductors (Saturable Reactors)

We have developed a robust solution targeting the high current, high voltage range requirements of DC furnace applications. The solution is transferable to all DC process applications.

Transductors offer a simple, robust control mechanism using two controlled DC current sources.

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Steel Core, Oil Cooled

A gapped steel core reactor immersed in oil offers a well controlled reactance and effective cooling in high current applications. The reactor is generally compact and well protected.

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Air core, air/water cooled

A drawback with steel core reactors is that they can saturate under adverse conditions, effectively removing their reactance from the circuit. This is not tolerable in AC and DC furnace applications, hence the requirement for air core reactors. The resistive losses can become prohibitive at large current ratings, so one often resorts to water or oil cooled busbars in the reactor.

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