MRCD residual current device in accordance with DIN EN 60947-2
What is an MRCD (Modular Residual Current protective Device)?
RCD (Residual Current Device) is the generic term for all types of residual current devices. Along with the MRCD, this product group, inter alia, includes RCCB, RCBO and CBR. All previously mentioned devices are able to recognise a fault current and to isolate the circuit being monitored in the event of a fault. Disconnection required in accordance with DIN VDE 0100-410 will take place. In a wide range of areas these devices are required and recommended (DIN VDE 0100-530).
An MRCD is a circuit-breaker with assigned residual current detection in different component groups consisting of the following device combination:
- RCM Residual Current Monitor RCM(A)42x, RCMB
- W, WR, WF, W…AB(P) series measuring current transformers for almost any kind of operational currents
- Switching element with isolating properties (e.g. circuit breakers)
When the pre-alarm threshold is exceeded, a potential-free contact switches. Pre-alarm offers system operators numerous benefits, such as:
- Early information on the level of insulation prior to shutdown
Prevention of unscheduled system shutdowns
- Higher operational and electrical system safet.
When the set response value is exceeded the RCM's alarm relays switch and trigger the undervoltage release of the circuit breaker.
This device combination provides a protective device in accordance with DIN EN 60947-2 Annex M that fulfillls the following protection objectives, while taking into account the maximum disconnection times:
- Protection of persons
- Protection against fire
- System protection
When is an MRCD allowed to be used?
For applications in the industrial sector, in general an MRCD solution can be set up (DIN VDE 0100-530). Or when the operating current is not to be led via the terminals of an RCCB solution. Exception: An MRCD is not to be used for household installations (DIN VDE 0100-530).