What are the requirements for low frequency heating equipment for manufacturing special transformers and air core reactors?

A typical low-frequency heating unit for transformer winding drying is designed to heat windings to roughly +75°C to +120°C by passing low-frequency AC through the coils; units commonly provide adjustable frequencies from about 0.5 Hz to 10 Hz, AC output voltages up to ~400 V (automatic control) and output currents in the low-hundreds of amps (specs are typically up to 300 A AC, with sinusoidal output ratings commonly quoted to ~200 A depending on configuration). These units are intended to run in dry ambient conditions (0°C to 40°C), have ingress and impact protection (typical ratings IP54 and IK09), and often include automatic process control that continues heating until oil moisture reaches a target (commonly cited as <10 g/ton). They can be used alongside thermal vacuum dryers to speed moisture transfer from windings into oil, and power-supply parameters can usually be customized to customer needs.

Limitations and practical requirements to observe are straightforward: do not operate the equipment with internal moisture or condensation, verify the exact current/frequency ratings for your configured unit, and ensure ambient and enclosure protection are suitable for your site. The published capability set focuses on heating transformer windings; there is no explicit specification for air-core reactors or special transformer manufacturing in the standard product data, so for air-core reactors or atypical winding geometries you should confirm the heating method, required current/voltage, impedance and insulation class with the vendor or engineering team before applying LFD-style low-frequency heating.