Completing The Test - ABB RET670 Commissioning Manual

Section 10
Testing functionality by secondary injection
Above procedure can also be used to test definite time step. Pay attention that IDMT step can also
trip during such injection. Therefore make sure that appropriate settings are entered in order to
insure correct test results for definite time step.
10.5.14.2

Completing the test

Continue to test another functions or end the test by changing the Test mode setting to
Restore connections and settings to their original values, if they were changed for testing
purposes. Make sure that all built-in features for this function, which shall be in operation, are
enabled and with correct settings.
10.5.15 Negative-sequence time overcurrent protection for machines
NS2PTOC (46I2)
10.5.15.1 Verifying settings by secondary injection
1. Connect the test set for injection of three-phase currents to the appropriate current
terminals of the IED.
2. Go to Main menu/Settings/Setting group n/Current protection/NegSeqOverCurr2Step/
NSOn/General and make sure that the function is enabled, that is
Enabled .
3. Inject current into IEDs in such a way that negative sequence component is created and then
verify that negative sequence component of the injected currents is calculated correctly by
the function. See example below for 1 A rated current transformer.
4. Inject pure negative sequence current, that is, phase currents with exactly same magnitude,
reversed sequence and exactly 120° phase displaced into the IED with an initial value below
negative sequence current pickup level. No output signals should be activated.
Note: If it is difficult to obtain pure negative sequence current for the secondary injection
test, a current corresponding to the two phase short-circuit condition can be used. A two
phase short-circuit gives a negative sequence current of a magnitude: magnitude = (1/√3) ·
fault current.
5. Increase the injected current and note the value at which the step 1 of the function operates.
Pickup signal PU_ST1 must be activated when amplitude of the negative sequence current
lies slightly above the pickup level
activated after the pre-set time delay has expired.
Note: Block or disable operation of step 2 when testing step 1 if the injected current activates
the step 2.
6. Decrease the current slowly and note the reset value.
162
Note that it is recommended to test IDMT operating times by injected current with
the rated frequency.
When inverse time overcurrent characteristic is selected, the trip time of the stage
will be the sum of the inverse time delay and the set definite time delay. Thus, if
only the inverse time delay is required, it is important to set the definite time delay
for that stage to zero.
I2-1> . Corresponding trip signals TRST1 and TRIP is
1MRK 504 154-UUS B
GUID-5AB7880E-629C-45E5-AF91-3EBDF19DEA79 v2
Disabled .
GUID-48A6DA1D-5CF5-4C1B-B1A4-3F2C73851FD4 v2
GUID-F7AA2194-4D1C-4475-8853-C7D064912614 v4
GUID-EB788169-532A-4A3E-BBEC-DCB28169DF86 v6
Operation is set to
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