FI block size x250 4-pole 250A Idn adjustable. Electronic FI block in accordance with DIN EN 60947-2 for retrofitting to circuit breakers and load break switches. Built in a modular design for easy attachment to the circuit breakers or load break switches. The residual current sensitivity and the tripping time can be set on the device. Both a mechanical and an electrical test button are available for tripping testing. Display (via LED on the device), remote display and the tripping warning of I delta n at 50% are available.