Fisher Pierce® series 1301 PowerFlex high-accuracy Line-Post Current Sensors provide reliable current measurement for distribution systems - from zero to thousands of amps. The sensor consists of a porcelain line-post insulator with an embedded coil, which is inductively coupled to the conductor mounted in the insulator top groove. The voltage induced in the coil is directly proportional to the alternating current in the primary conductor. This signal may be used for capacitor switching, load surveying or protective relaying.