Equipments such as, capacitors or rotating
machines being connected after the RCD may
cause an essential prolongation of the calcu-
lated trip time.
Contact voltage measurement may be influ-
enced by potential fields of other grounding
systems.
Particular conditions of special built RCDs (e.g.
selective or surge current resistant versions)
must be taken into consideration for the tests.
The UNITEST ELECTROcheck is not the appro-
priate instrument to test selective RCDs.
If the residual current circuit breaker already
trips during contact voltage test, the warning
symbol (14), the symbol 'test current error'
(18), and 'socket error’ (4) are displayed. When
testing the trip time, the 'OK” (6) symbol is dis-
played, additionally.
Figure 5.5.1: Display for RCD tripping caused by
contact voltage test
In this case, check if the rotary switch 'Mea-
surement function’ is set to the correct nomi-
nal fault current. If an incorrect fault current
has been selected, the current bias of the pro-
tective conductor is possibly at such a high
level, that the residual current circuit breaker
trips due to the test current; or the residual cur-
rent circuit breaker might be defective.
If the warning symbol (14) and the symbol ‘test
current fault” (18) are displayed during the test
without display of the socket error symbol
(11), then the integrated instrument fuse has
blown and must be replaced. Please refer to
section 9.0
Figure 5.5.2: Display for defective fuse
No foreign voltage may be present at the pro-
tective conductor for the contact voltage test.
If, however, a foreign voltage is present, the in-
strument only evaluates the voltage during the
contact voltage test that has been self-gener-
ated by the test.
A test interruption during the trip test by ex-
ceeding the limit value (25 V) is, however,
caused by the actual voltage present between
neutral conductor (N) and the protective con-
ductor (PE).
22
General Information Regarding RCD Tests
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