Current transformer excitation, ratio, and polarity test set

  • Tests current transformers mounted in transformers or switchgear
  • Saturation, ratio and polarity tests performed without changing test lead connections
  • Overload and short-circuit protection
  • Provides a low range of 40 volts and a high range of 1000 volts

The CTER-91 current transformer excitation, ratio, and polarity test set is a lightweight, portable unit for performing excitation, ratio, and polarity tests on current transformers (CTs) using the voltage-comparison method.

Using the latest technology, the CTER-91 provides a variable voltage output and precision instrumentation for testing single and multi-ratio CTs. All three tests – excitation, ratio, and polarity – can be performed without changing any leads. CTs can be tested in their equipment configuration, such as being mounted in transformers, oil circuit breakers, or switchgear. However, it is necessary for the equipment to be totally isolated from the electrical system prior to testing.

The CTER-91 has a voltmeter to measure external voltages up to 600 volts AC and a RUN/HOLD switch that freezes readings on instruments when switched to the HOLD position. It provides a low range of 40 volts for CTs that saturate at low voltages and provides a high range of 1000 volts. A zero-start interlock is incorporated to minimise the possibility of energising the CT under test with a sudden high voltage.