Medium Voltage Control Power Transformers

A medium voltage control power transformer is designed to step down medium voltage (typically 2.4 kV to 15 kV) to a safe, stable control voltage for auxiliary loads such as switchgear, motor starters, or relays. It provides galvanic isolation between the medium voltage distribution system and low-voltage control circuits, ensuring safety and reliability. These transformers are built for use in environments where dependable control power must be available directly from a medium voltage source, eliminating the need for a separate low-voltage supply.

The primary difference lies in construction and insulation. Medium voltage control power transformers are designed to handle much higher primary voltages than standard control transformers. They use encapsulated coil construction, high-dielectric insulation systems, and extended creepage distances to safely manage the electrical stress of medium voltage operation. The encapsulated design also protects windings from dust, moisture, and contamination. This ensures long-term reliability, stable performance, and compliance with the requirements of switchgear, substations, and heavy industrial systems.

These transformers are used wherever auxiliary low-voltage power is required from a medium voltage source. Common applications include industrial substations, motor control centers, switchgear panels, power generation plants, and remote installations. They supply control power for relays, instrumentation, lighting, or communication systems when a secondary service voltage is not available. The encapsulated coil design ensures reliable operation in demanding environments, providing electrical isolation and protection for sensitive control components even in the presence of high transient voltages.

All medium voltage control power transformers are designed and tested in accordance with CSA C9, CSA C22.2 No. 66, and IEEE C57 standards. Units are CSA certified and manufactured under Rex Power Magnetics’ ISO 9001-certified quality management system. The encapsulated coil construction provides superior environmental and electrical protection while ensuring compliance with applicable North American and international safety requirements.

Reliability is achieved through careful material selection and encapsulated coil construction. The encapsulant protects windings against moisture, dust, and vibration while enhancing heat dissipation and dielectric strength. The magnetic core is optimized for low losses and excellent voltage regulation. The combination of encapsulated design, precision winding, and rigorous testing ensures consistent operation under high-stress conditions such as switching transients, inrush currents, and voltage fluctuations. These features make Rex Power Magnetics transformers ideal for mission-critical control applications.

Encapsulated medium voltage control power transformers are low-maintenance devices. Routine inspection should include verifying terminal connections, cleaning the enclosure exterior, and checking for signs of overheating or corrosion. The encapsulated coil design eliminates the need for varnish re-application or insulation reconditioning. When operated under normal load and ambient conditions, these transformers deliver long service life with minimal upkeep. Periodic visual inspection ensures continued electrical integrity and early detection of mechanical wear in high-duty installations.

Yes. Rex Power Magnetics specializes in custom designs for specific industrial and utility applications. Customization options include primary voltage ratings up to 15 kV, special secondary voltages, insulation levels  and integrated protective devices such as fuses. Our engineering team can assist in optimizing form factor, thermal performance, and environmental protection. Each custom-built transformer undergoes the same rigorous testing and quality control as standard models, ensuring long-term reliability and compliance with project specifications.