JST is one of the world's largest and most reputable manufacturers of medium-voltage cast resin transformers from 150 kVA to 20,000 kVA. Below is some basic information about our products:

JST transformers use the proven May-Christie type design, employing a core cruciform construction with a mitered step lap.


  • Both HV & LV windings vacuum cast in epoxy
  • Step-lap mitered cruciform core
  • 185°C cast epoxy insulation system
  • Vibration isolators protecting core and coil


  • Primary voltages up to 34.5 kV
  • UL Class H insulation systems – 185°C
  • Temperature rises of 115°C and 80°C
  • Basic Impulse Levels (BILs):
    > Primary: 60 kV – 200 kV
    > Secondary: 10 kV – 95 kV

Our transformers meet the standards of:

  • IEC
  • CSA
  • UL
  • NEMA
Our coils, both primary and secondary, are fully cast in epoxy resin. This achieves the highest mechanical strength, dielectric strength, and reliability.

We use a knock-down type enclosure made of cold rolled steel and finished with electrostatic powder paint.

Available options include:

  • Indoor or outdoor enclosures
  • With or without fans
Our cast resin transformer.
Copyright @ 2009 Jinpan International USA Limited  l  Tel. 201.460.8778  l  Fax. 201.460.8775  l