Negative-Sequence Time Overcurrent Protection For Machines Ns2Ptoc (46I2); Verifying Settings By Secondary Injection - ABB Relion 670 Series Commissioning Manual

Section 11
Testing functionality by secondary injection
11.5.17 Negative-sequence time overcurrent protection for machines
NS2PTOC (46I2)
11.5.17.1

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 /IED Settings/Current protection /NegSeqOverCurr2Step/NSOn /
General and make sure that the function is enabled, that is Operation is set to 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 I2-1>. Corresponding trip signals TRST1 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.
8. Set the current to 200 % of the pickup level of the step 1, switch on the current and check the
definite time delay for trip signals TRST1 and TRIP. Once the measured negative sequence current
exceeds the set pickup level I2-1>, the settable definite timer t1 starts to count and trip signals is
released after the set time delay has elapsed. The same test must be carried out to check the
accuracy of definite time delay for ALARM signal.
Note: The output ALARM is operated by PICKUP signal.
9. If inverse time is selected the trip signals TRST1 and TRIP operates after a time corresponding to
the formula:
196
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.
t s
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Multiple of Pickup
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1MRK 504 165-UUS Rev. J
GUID-48A6DA1D-5CF5-4C1B-B1A4-3F2C73851FD4 v2
GUID-F7AA2194-4D1C-4475-8853-C7D064912614 v4
GUID-EB788169-532A-4A3E-BBEC-DCB28169DF86 v7
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Transformer protection RET670
Commissioning manual