Current Transformers (CT's) take a high current and reduce it to 5 amps on the secondary winding so that it can be used with a watthour meter, ammeter, or digital panel meter. The rating of an instrument transfer is expressed by two groups of numbers representing the nominal current or voltage which may be applied to its primary winding and the current or voltage which would then be induced in its secondary winding. a designation of 600:5 amperes expresses the rating of a current transformer and means that when 600 amperes flow through the primary, 5 amperes will flow through the secondary. This 5A output from the secondary winding is an industry standard range that is available in most input panel meters and controls.

Current Transformers can be solid-core, round or square, or split-core with a flexible opening to allow installation over a conductor without an interruption in power. Within this line of CT's, current can be monitored on primary conductors up to 6000 amps with apertures of up to 8" in diameter. They are designed for indoor or outdoor applications and are fully encapsulated and rubber molded to protect against moisture, dirt, oil and corona. All models have an accuracy of +/-1% over their stated range.