Meant for testing of instrument-class current transformers, CTCS-3.3 includes input scaling converters (instrument CTs) and commutation unit.

Its circuit provides that 2 currents (from the reference CT & CT-under-test) are measured and compared.

With Energomonitor 3.3T1, CTCS-3.3 makes it possible to measure ratio and angle errors of instrument current transformers of 0.2S accuracy class with nominal secondary current 1A or 5A.