Switchgear Style Current Transformers

General Details

Switchgear Style Current Transformers










Switchgear Style Current Transformers (CTs) available in 600 v class, Model 780, with CSA approval. These current transformers can be used for measuring, and protection applications inside of both switchgear and medium voltage breaker apparatus.

Switchgear Style Current Transformers are a Relay Class type of current transformer from Class C10 to C200, depending on current ratio, and have standard secondary terminals for ease of installation. Ratios available range from 50 to 6,000 amps with a 5 amp secondary. Window diameter is 6.50 inches round for easy installation.

Multi Ratio CTs are also available in Model 781 series, per attached specs (see above ‘Specs’ heading) with same window size 6.50 inches round, with multi ratios availability depending on the 5 available models.

A Current Transformer (CT) is a type of transformer that is used to reduce or multiply an alternating current (AC). It produces a current in its secondary which is proportional to the current in its primary.

Current Transformers, along with voltage or potential transformers, are instrument transformers. Instrument transformers scale the large values of current to small, standardized values that are easy to handle for measuring instruments and protective relays. The Instrument transformers isolate measurement or protection circuits from the high voltage of the primary system. These units provide a secondary current that is accurately proportional to the current flowing in its primary, presenting a negligible load to the primary circuit.

These units are the current sensing units of the power system and are used at generating stations, electrical substations, and in industrial and commercial electric power distribution.

Advantages of Current Transformers are that the units can measure high current easily, high electrical isolation, simple construction, and easy maintenance and installation.


  • 600 V Class
  • Multi Ratio Models available (5 models to choose from)
  • Ratios available: 50 to 6,000 to 5 amp ac secondary
  • Relay Class C10 to C200 (depending on ratio)
  • Secondary Terminals
  • Standard Meter Output
  • Window diameter 6.50 inches round



  • CSA
  • UL


Model 780

Model 780


Single Ratio CT:

780 (6.50″window)(50-4000 A)(relay class C10-C200)


Multi Ratio’s CTs:

781-601MR (6.50″ window)(50-600A Multi Ratio)(relay class C10-C100)

781-122MR (6.50″ window)(100-1200A Multi Ratio)(relay class C10-C200)

781-202MR (6.50″ window)(300-2000A Multi Ratio)(relay class C20-C200)

781-302MR (6.50″ window)(300-3000A Multi Ratio)(relay class C10-C200)

781-402MR (6.50″ window)(500-4000A Multi Ratio)(relay class C20-C200)

  • CSA
  • UL