Connect the secondary test set to the CT inputs on the IED dedicated for the SCB currents.
Single- or three-phase test equipment can be used but it may be required to have facility
to vary the frequency of the injected current signal(s).
11.5.13.1 Verifying the settings and operation of the function
Reconnection inhibit feature
1. Inject SCB rated current (that is, 0.587A at 50Hz for this SCB) in at least one phase
(preferably perform this test with three phase injection).
2. After couple of seconds stop injection of all currents (that is, set all currents back to
0A).
3. Check that function binary output signal RECNINH is set to logical 1 and that only
resets after the set time under parameter tReconnInhibit (for example 300s for this
SCB) has expired.
4. If this binary signal is used to prevent CB closing make sure that it is properly
connected/wired into the CB closing circuit.
Overcurrent feature
Note that during testing the overcurrent feature the harmonic voltage
overload feature or reactive power overload feature may also give pickup
and trip signals depending on their actual settings. Therefore it is best to
switch them off during this test.
1. Inject current 20% bigger than the set overcurrent pickup level under setting
parameter PU 51 (for example, 1.2 · 1.35 · 0.587A = 0951A at 50Hz for this SCB)
in phase A only.
2. Check that function binary output signals PU_51_A and PU_OC are set to one.
3. Check that function binary output signals TROC and TRIP are set to one after the set
time under parameter tOC (that is, 30s for this SCB) has expired.
4. If any of these signals are used for tripping, signaling and/or local/remote indication
check that all relevant contacts and LEDs have operated and that all relevant
GOOSE messages have been sent.
5. Check that service value from the function for current in phase A, on the local HMI
under Main menu/Test is approximately 476A (that is, 0.951A · (500/1) = 476A).
6. Stop injection of all currents (that is, set all currents back to 0A).
7. Check that all above mentioned function binary output signals now have logical
value zero.
8. Repeat above steps 1-7 for phase B and phase C.
Section 11 1MRK 504 165-UUS -
Testing functionality by secondary injection
202 Transformer protection RET670 2.2 ANSI
Commissioning manual
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