16
Commissioning
and testing
The relay incorporates a self-supervision logic
that continuously supervises the operation of
the relay and provides an IRF alarm when an
internal relay fault is detected. However, the
manufacturer recommends regular testing of the
relay, for instance, every five years. This test
should be carried out as a primary test, which
includes the entire supervision chain covered by
the synchro-check relay, from the instrument
transformers to the circuit breakers.
Special attention should be paid to the connec-
tion of the relay. Further, it should be checked
that the primary side wiring is correct. The ta-
ble below can be used for checking the wiring.
Measuring circuit
wiring and wiring
test
Faulty wiring of the voltage inputs of the relay
will cause malfunction in the synchro-check re-
lay. If the wires of an energizing input have
changed places, the polarity of the voltage of
the input is reversed (180
°
). Then the relay per-
mits circuit breaker closing in a situation where
the voltages actually are in opposite phases. For
this reason it is extremely important that the
wiring from the voltage transformers to the ter-
minals on the rear of the relay is consistent re-
garding the energizing inputs U1, U2 and U3.
The table below shows the energizing inputs and
the related terminals.
Energizing input U1/100 V
Energizing input U2/100 V
Energizing input U3/100 V
Terminal
13
16
19
14
17
20
Energizing input U1/110 V
Energizing input U2/110 V
Energizing input U3/110 V
Terminal
13
16
19
15
18
21
The wiring should be verified by checking the
reading of the phase difference measured be-
tween the voltages U1 and U3 and between the
voltages U2 and U3. When checking the phase
differences the circuit breaker between the con-
cerned voltages have to be closed, to make sure
there is no phase difference. The phase differ-
ence measured by the relay has to be close to
zero within the permitted accuracy tolerances.
The phase differences measured are indicated
in the third submenu of the LEDs U1 and U2.
At the same time it is recommended to check
the voltage difference and the frequency differ-
ences presented in the first and the second sub-
menu, respectively. These values should be
within the permitted tolerances, close to zero.
The frequency measured from the network, for
example 50 Hz, can be read in the first sub-
menu of the U3 indicator.
