ABB Relion 670 series, Installation And Commissioning Manual

Page: 195 / 260

15.6.11.2 Completing the test
Continue to test another function or end the test by changing the Test mode setting
to Off . Restore connections and settings to their original values, if they were
changed for testing purposes.
15.6.12 Negative-sequence time overcurrent protection for
machines NS2PTOC
When inverse time overcurrent characteristic is selected, the
operate 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 of utmost importance to set the definite time delay
for that stage to zero.
15.6.12.1 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 Operation is set to On .
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 start 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. Start signal ST1 must be activated when amplitude of the
negative sequence current lies slightly above the start level
I2-1> .
Corresponding trip signals TR1 and TRIP is 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.
7. Connect a trip output contact to a timer.
1MRK 502 029-UEN A
Section 15
Verifying settings by secondary injection
189
Installation and commissioning manual