Rogowski coils suit relay protection and measurement [of power systems]

Microprocessor-based technology has been accepted today in virtually all areas of electrical engineering, including power. Input signals that accurately replicate events are critical for the proper operation of microprocessor-based equipment. Therefore, current sensors are an integral element of relay protection and current measuring systems. Current transformers (CTs) have been used exclusively for protection and measurement applications in part because of their ability to produce the high power output needed by electromechanical equipment. The introduction of microprocessor-based equipment has made the high-power output of CTs unnecessary and made the use of other measurement techniques possible. One such measuring device that does not produce high-power output but offers many advantages over CTs is the Rogowski coil. This article describes Rogowski coil operational characteristics and it applications for current measurements