MK Electric Catalogue No. 49

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CIRCUIT PROTECTION
594
Sentry Technical
Industrial 10kA Residual Current Devices (RCDs)
Operation
The RCD provides an indication of an earth fault and contact
status as detailed below.
The operating dolly provides the following indication:
I = Switched ON
+ = Switched OFF due to Earth Fault or test button operation
0 = Switched OFF
The contact status is shown through the window.
Red = contact closed
Green = contact open (RCD is switched off)
In the event of an Earth Fault in the installation or the operation of
the test button, the dolly will move to the central position (+) and the
contact status indicator shows green. To re-connect the supply the
dolly must be reset by moving to the off position before switching on.
Testing
If an RCD is installed for additional protection against indirect
contact, it is a requirement of the IEE Regulations that the
effectiveness of the RCD be verified. This must be achieved by a
test simulating an appropriate fault condition and be independent
of any test facility incorporated in the RCD. The test currents to be
applied are as follows:
Test current Condition
0.5 x l ∆ n RCD must not trip
1.0 x l ∆ n RCD must trip within 300mS
5.0 x l ∆ n RCD must trip within 40mS
Where l ∆ n is the RCD’s rated tripping current in accordance with
wiring regulations and product standard BS EN 61008.
For time delay RCD 1.0 x l ∆ n RCD must trip between 130-
500mS.
RCD
T
1 3
2 4
7700s 100A 30mA
230V
E
PUSH TO TEST
-25
RCD
T
1 3
2 4
7700s 100A 30mA
230V
E
PUSH TO TEST
-25
RCD
T
1 3
2 4
7700s 100A 30mA
230V
E
PUSH TO TEST
-25
ON
RESET
OFF