This sensor is used for earth-fault detection. The potential-free connection between the sensor and the display unit is done by a fibre optic cable. The sensor must be mounted on screened cables.
A divisible layered steel ring is laid around all the three phases to measure the sum current. Therefore the sensor can be retrofitted. The sensor is fixed on the conductor or cable with a cable tie-wrap.
The trip current can be selected by a 7-step rotary switch.