Verifying The Operate Characteristic - ABB Relion 670 Series Commissioning Manual

1MRK 504 165-UEN E
•
3. Check that the trip and alarm contacts operate according to the configuration logic.
4. Decrease the current slowly from operate value and note the reset value.
5. Repeat the procedure by injecting current in phases L2 and L3 respectively.
11.3.5.8

Verifying the operate characteristic

1. Connect the test set for injection of two three-phase current sets to the current
terminals of the IED, which are connected to the CTs on the winding one and winding two
sides respectively of the power transformer.
2. Inject the x-times (where, x = any value between 1.25*
the rated load current using the positive sequence current systems only on both sides of
the PST.
For actual secondary current magnitudes of the rated PST load, see tests for zero-
sequence current reduction given above. For more details on how to calculate
magnitudes and the phase angles for the six currents to be injected, refer to the paper
Easy and Intuitive Method for Testing Transformer Differential Relays published by ABB.
When correct currents are injected, check that all three differential currents are
approximately 0% and the bias current is equal to x*100%. These values are available as
outputs and service values from the PSTPDIF function. At this point, a stable condition
for bias current of x*100% is being injected.
3. If the factor x has a value greater than 5, make sure that the testing is done relatively
quickly to avoid overheating of the input current transformers inside IED. Their
continuous rating is 4 times the rated current (i.e. 1 A or 5 A secondary).
Transformer protection RET670
Commissioning manual
For phase angle shifts greater than ±60 degrees, actual operation
will happen in one of other two phases where current has not been
injected.
When ZSCurrSubtrW2 = On , this factor will have a value between 1.50 and 1.732
depending on the actual phase angle shift as shown in
IEC18000248 V1 EN-US
Figure 24: Single-phase pickup factor when ZSCurrSubtrW2 = On
For phase angle shifts greater than ±30 degrees, actual operation will
happen in one of the other two phases where the current has not been
injected.
The pickup current is dependent on the actual phase angle shift across
the protected PST.
© Copyright 2017 ABB. All rights reserved
Testing functionality by secondary injection
Figure 24:
GUID-2A65B94E-3525-4022-A237-B8ABC596DC92 v1
IdMin and 0.95* IdUnre parameters)
Section 11
105