Transformers for Harsh Environments

A transformer installed in a demanding industrial environment must be designed taking into account much more than just its electrical characteristics. Dust, water, snow, corrosion, equipment movement, or mechanical stress can all influence its construction. WR transformers are used in some of the harshest environments, particularly in mines across the Canadian Far North and aluminum smelters where equipment must support demanding operations. 

Protection starts notably with the windings. Copper or aluminum coils are vacuum pressure impregnated using the VPI process with a polyester resin to ensure complete impregnation of the windings and their insulation. According to WR, this VPI construction enhances reliability and longevity during operations carried out in hostile environments. The transformers also use UL-approved 220 °C class insulation. 

The core is manufactured from grain-oriented steel featuring high magnetic permeability. The steel is precision-cut and coated with a finish designed to resist corrosion. Its flux density is maintained below the saturation point to reduce core losses and sound levels. On larger-capacity units, an air gap can be integrated to limit saturation and allow air to circulate to aid in cooling. 

In certain mining applications, mechanical strength also becomes a design criterion. WR indicates that transformers intended for the mining sector can be mechanically reinforced so they can be handled when oriented at 90 degrees. The coils are also compressed using insulation blocks installed between the upper and lower frames to improve their ability to withstand the forces generated by a short circuit. 

The enclosure serves as another important barrier between the transformer and its environment. WR offers NEMA 1 and NEMA 3R enclosures, which can be equipped with filters designed to protect the equipment against dust, water, or snow. Several enclosure thicknesses are available to achieve the required rigidity. In particularly corrosive environments, especially those exposed to salt air, the enclosure can also be fabricated from stainless steel. In addition, WR offers a non-ventilated configuration designed to withstand particularly severe weather conditions. 

For mining applications, the transformer and its accessories can also be mounted on a solid metal base. This configuration makes the unit easier to transport and can reduce the number of connections required with control panel components during relocation or installation. 

Connections can also be tailored to the site's realities. Transition chambers notably allow cables to enter from the top and facilitate high- and low-voltage connections. Cable supports can be added to make installation simpler and safer. Flexible braids can also limit the transmission of vibrations between the transformer and the equipment to which it is connected. 

Finally, this construction is supported by a testing process carried out at WR facilities. Each transformer undergoes routine testing, and additional tests can be performed based on project specifications. WR's testing laboratory is ISO/IEC 17025 certified, while the company also cites ISO 9001-2015, CE, UL, CSA, CSAus, and ULcan certifications.