Manual WIP1 GB
Woodward
DOK-TD-WIP1 Rev.F
47
7.2.4 Checking the input circuits and measured values
Inject a current, which is less than the relay pickup cur-rent set values, in phase 1 (terminals 1S1-1S2), and
check the measured current on the display by pressing the push button <SELECT/RESET>. The current can
be also injected into the other current input circuits (Phase 2: terminals 2S1-2S2, Phase 3: terminals
3S1-3S2. Compare the displayed current value with the reading of the ammeter. The deviation must not ex-
ceed 5% In. By using an RMS-metering instrument, a greater deviation may be observed if the test current
contains harmonics. Because the WIP1 relay measures only the fundamental component of the input sig-
nals, the harmonics will be rejected by the internal DFFT-digital filter. Whereas the RMS-metering instrument
measures the RMS-value of the input signals.
7.2.5 Checking the overcurrent element
To check the relay operating time, a timer must be connected to the trip output relay contact. The timer
should be started simultaneously with the current injection in the current input circuit and stopped by the trip
relay contact. Set the current to a value corresponding to twice the operating value and inject the current in-
stantaneously. The operating time measured by the timer should have a deviation of less than 3% of the set
value or ±10 ms (DEFT). Accuracy for inverse time characteristics refer to IEC 255-3.
Repeat the test on the other phases or with the inverse time characteristics in the similar manner.
In case of inverse time characteristics the injected cur-rent should be selected according to the characteristic
curve, e.g. two times IS. The tripping time may be red from the characteristic curve diagram or calculated
with the equations given under "technical data".
Please observe that during the secondary injection test the test current must be very stable, not deviating
more than 1%. Otherwise the test results may be wrong.
7.2.6 Checking the high set element of the relay
The high set element of the WIP1 is checked in the same manner. It is important, however, that the selected
test current is not too high because of trip delay at inverse time characteristics may become shorter than the
high set setting. The reason is that both tripping signals operate the same tripping relay or the same electric
impulse output.
Note !
Where test currents >2.5 x I
N
are used, the thermal withstand capability of the current paths has to be con-
sidered (see technical data, chapter 7).