Verifying The Zero-Sequence Current Reduction From The Winding One Side; Verifying The Three-Phase Pickup From Winding One Side - ABB Relion 670 Series Commissioning Manual

Section 11
Testing functionality by secondary injection
and DIFANGLE outputs have value that corresponds to the PST tap position at which the function
needs to be tested.
4. Apply the logical value one to the binary input STOPCOMP into PSTPDIF function. The function will
now remember the transformation ratio and phase angle shift, which corresponds to this particular
PST tap. These two values will be stored and used as long as the input STOPCOMP has a logical
value one. To perform this, the IED shall be configured accordingly beforehand. Typically, one front
LHMI key or one binary input can be configured in the configuration tool to perform this task. If
additional security is needed, this action can be only allowed when the IED is in Testmode.
5. Interrupt all six currents from the test set and verify that DIFRATIO and DIFANGLE outputs still
have value that corresponds to the PST tap position, at which the function needs to be tested.
The function is now prepared to be tested at this particular tap position in a similar way as the
standard transformer differential protection.
The following sections explain how the PSTPDIF shall be tested for this particular tap position. Note that,
the above procedure and the following tests shall be repeated for every PST tap position, at which the
function needs to be tested.
Note that the following tests can be used for any dedicated tap-position available in the protected PST. In
actual installation, perform these tests for two extrema tap positions, mid-tap position and one or two
more freely selected tap-position(s).
11.3.5.2

Verifying the zero-sequence current reduction from the 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 current in all three phases with equal magnitudes corresponding to the rated load of the PST
(i.e. 100%) in secondary amperes as given below:
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:
102
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 (87T) 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 (87T) 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 (87T) function.
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1MRK 504 165-UUS Rev. J
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(Equation 1)
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Transformer protection RET670
Commissioning manual