Current Transformers

WHAT IS CURRENT TRANSFORMER

Current transformers convert an alternating current usually high in to a proportional lower one, depending on their use, Measurement type CTs are required to transform the primary current, at various classes of accuracy, as specified by the   class designation, over a current range from 1 to 120 percent of its rated primary ratio. The design of this type of transformer requires the inclusion of a core and winding which will when connected to its rated burden; perform within the limits of error as indicated by the standard’s specification. It is an advantage for a measurement type transformer to saturate above this range, which provides a protection against damage to instruments by limiting the secondary current when surge currents or faults appear in the primary circuit.

MEASURING TRANSFORMER

A current transformer intended to supply indicating instruments integrated meter, relay and similar apparatus.

CURRENT TRANSFORMER

An instrument transformer in which the secondary current, in normal condition of use, is substantially proportional to the primary current and differs in phase it by an angle which is approximately zero fo
r an appropriate direction of connections.

RATED PRIMARY CURRENT

The value of primary current which appears in the designation of the transformer and on which the performance of the currant transformer is based.

RATED SECONDARY CURRENT

The value of secondary current which appears in the designation of the transformer and on which the performance of the currant transformer is based.