Transformer Rectifiers

Certain industrial applications impose very specific electrical requirements. This is particularly the case for processes requiring high currents. Dry-type rectifier transformers manufactured by WR are used in several of these applications, notably for the electrochemical production of chlorine, copper, aluminum, and magnesium. 

To meet the various configurations required by these processes, WR’s engineering and manufacturing team has the capability to build and test transformers according to project-specific requirements. Available configurations can include 6, 12, 24, or 36-pulse systems. Secondary side connections can also be adapted, with delta, wye, or zigzag wye configurations.

This adaptability is part of WR’s overall approach to design. The company develops and manufactures its dry-type electrical transformers in North America and has facilities capable of producing high-power units exceeding 20 MVA, with voltages up to 49 kV and an insulation class of up to 220 kV BIL. 

Winding construction can be tailored to the required voltage level and insulation class. The coils, made of copper or aluminum, are vacuum pressure impregnated (VPI) with a polyester resin. Depending on the application, windings can be layer-wound or disk-wound. For certain low-voltage windings, strip conductors can also be used to reduce eddy current losses and increase short-circuit strength. In addition, WR transformers utilize UL-approved 220°C class insulation. 

Special attention is also paid to the core. It is constructed from grain-oriented steel with high magnetic permeability. The magnetic flux density remains below the saturation point to reduce core losses and noise levels. For larger-capacity units, an air gap can be added to assist with cooling and prevent core saturation. 

The mechanical and electrical integration of the transformer can also be adapted to the equipment to which it connects. WR can manufacture and install busbars coordinated with low- or high-voltage switchgear as well as transition sections. Flexible braid connectors can be added to prevent transformer vibrations from being transmitted to connected switchgear devices. These components can be factory-installed so that the entire assembly is ready for on-site connection. 

WR rectifier transformers are manufactured and tested in accordance with IEEE, ANSI, CSA, and UL standards. Each transformer undergoes the company’s testing process, which includes dielectric tests, excitation at rated voltage, polarity and ratio verification, winding resistance, as well as load loss and impedance measurements. Additional tests can be performed based on project requirements. WR’s testing laboratory is ISO/IEC 17025 certified.