Accessories
4.8 Residual current devices
3VA molded case circuit breakers with IEC certificate
478
Manual, 03/2019, A5E03603177010-03
4.8.3
Modular residual current device
Thanks to their design, the modular residual current devices (MRCD) type A 5SV8101-6KK
and type B (5SV8101-4KK, 5SV8111-4KK / 0 to 2000 Hz) are compatible with all molded
case circuit breaker designs and can therefore be combined with 3VA1 molded case circuit
breakers/switch disconnectors and with molded case circuit breakers from the 3VA2 range.
The MRCD is installed on a DIN rail (35 mm) as close as possible to the molded case circuit
breaker/switch disconnector.
Operating principle
The MRCD is connected to a summation current transformer through which all live
conductors (including neutral conductor where applicable) must be routed. The residual
current is detected in the summation current transformer and transferred to the MRCD. If this
current exceeds the limit value for the set rated residual current I
Δn
, the residual current
device trips the molded case circuit breaker/switch disconnector by means of a shunt trip or
undervoltage release.