Old products
The D-serie is based on knowledge within ARC-detection since 1962.
The arc detecting relay is connected to light sensitive detectors suitable placed in the various cubicles or drawers inside the switchboard. the overcurrent relay is used if overcurrent as well as an arc has to be present before the supply circuit breaker is tripped. However, arcing time is hereby increased.
The time relay is an extra security. It is design to trip a back-up breaker further back in the supply with a time delay, if both an arc and an overcurrent are present after tripping of the supply breaker.
Below you find a number of documents which covers the D-serie program, which still are produced.