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Section 11
Testing functionality by secondary injection
I
Injected W
IECEQUATION18061 V1 EN-US
11.3.5.3
Verifying the three-phase pickup from winding one side
1.
Connect the test set for three-phase currents injection to the current terminals of the IED, which
are connected to the CTs on the winding one side of the power transformer.
2.
Inject symmetrical three-phase currents (for example, positive sequence current only). Increase
the current magnitude symmetrically in all three phases until the protection function operates
and note the operating current. The operating secondary current should have the following
value:
I
Pickup
IECEQUATION18058 V1 EN-US
3.
Check that the trip and alarm contacts operate according to the configuration logic.
4.
Decrease the current slowly from the operate value and note the reset value.
5.
Switch off the currents and connect an external timer to measure the operate time of the
function. Set the current in all three phases to twice the above measured pickup value.
6.
Switch on the currents and note the operate time of the PSTPDIF function.
7.
Check that the trip information is stored in the IED internal Event List and Disturbance
Recorder.
8.
Check that the trip information is properly indicated on the LHMI LEDs.
11.3.5.4
Verifying the single-phase pickup from winding one side
1.
Connect the test set for three-phase currents injection to the current terminals of the IED, which
are connected to the CTs on the winding one side of the power transformer.
2.
Increase the current magnitude in phase L1 only until the protection function operates and note
the secondary current at the moment of pickup. The operating secondary current should have
one of the following two values:
•
•
98
CTsec
W
1
*
I
_ 1
Base W
_ 1
CTprim
W
1
The phase angle for all three injected currents on the test set shall have the same
value of zero degree. As a consequence, the PSTPDIF function will work in either
of the following two ways:
•
Trip, if the parameter ZSCurrSubtrW1 = Off and all three differential currents
and the bias current shall be 100%. These values are available as outputs
and service values from the PSTPDIF function.
•
Not trip, if the parameter ZSCurrSubtrW1 = On and all three differential
currents and the bias current shall be 0%. These values are available as
outputs and service values from the PSTPDIF function.
CTsec
W
1
*
IdMin I
*
3
Ph W
CTprim
1
W
1
The pickup current is independent of the actual phase angle shift across the
protected PST.
Equal to the tested three-phase pickup value from winding one side if the parameter
ZSCurrSubtrW1 = Off.
Greater for factor 1.5 from the tested three-phase pickup value from winding one side if
the parameter ZSCurrSubtrW1 = On.
© 2017 - 2022 Hitachi Energy. All rights reserved
Base W
_ 1
1MRK 504 165-UEN Rev. K
(Equation 1)
GUID-FAD1B3C3-840F-4250-8617-6592CB90A951 v1
(Equation 2)
GUID-E3AF062D-9040-4784-831E-23F91638C69C v1
Transformer protection RET670
Commissioning manual
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