The flexible AC heads with DIN rail housing are based on the Rogowski principle. They are suitable for AC current measurements of a few 100mA up to 6000A. The electronics usually gets installed in the control cabinet, whilst the measuring heads can be mounted either directly by screw terminals or alternatively by socket outlet, plug, and cable up to 20m away from the electronics. The DRP and DRM series deliver a voltage output signal, which is directly proportional to the measured current. As well as single-phase, three and four-channel systems can be offered.