ABB RET670 Commissioning Manual page 211

1MRK 504 165-UUS -
Transformer protection RET670 2.2 ANSI
Commissioning manual
Note that operation of this feature is based on internally calculated voltage
peak RMS value. That means that this feature is also able to trip for current
signals with varying frequency.
Here will be shown how to test the fourth point from the above table. Other points can be
tested in the similar way:
1. Inject 140% of the base current (that is, 1.4 · 0.587A = 0.822A at 50Hz for this SCB)
in phase Aonly.
2. Check that function binary output signals PU_HOL_IDMT_A and PU_HOL are set
to one.
3. Check that function binary output signals TRHOL and TRIP are set to one after the
expected time (for example, 15s for this voltage level in accordance with the above
table) 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 for current in phase A, on the local HMI under Main menu/
Test is approximately 411A (that is, 0.822A · (500/1) = 411A).
6. Check that service value for voltage across SCB in phase A, on the local HMI under
Main menu/Test is approximately 140%.
7. Stop injection of all currents (that is, set all currents back to 0A).
8. Check that all above mentioned function binary output signals now have logical
value zero.
9. Repeat above steps 1 - 8 for phase B and phase C.
10. Repeat above steps 1 - 8 to test different points from the above table.
Operation of this feature is based on internally calculated peak RMS voltage value. That
means that this feature is also able to trip for current signals with varying frequency. Note
that for the fundamental frequency injection, internally calculated voltage in percent
corresponds directly to the injected current value given in percent. However if it is
required to test IDMT characteristic with a varying frequency, the magnitude of the
injected current must be adjusted accordingly. The following formula can be used to
calculate required current RMS value in percent at the desired injection frequency in order
to archive voltage percentage value given in the above table:
f
[ ]
[ ]
%
=×
injected
I %
.V
inj
f
rated
EQUATION2274-ANSI V1 EN
Testing functionality by secondary injection
Section 11
(Equation 90)
205