Differential Module of Protection Scheme

Differential

1. Differential Relay testing

2. Theory of Differential protection
•Protection is based on Kirchhoff Current law.
•Cover complete protection of the Transformer
•Act on the basis of residual current flow in the relay.
Fig: Principle of Differential Relay

3. Theory of Differential protection
•Added bias Current concept to provide additional
stability for external fault
•Differential Characteristic for protection
Fig: Differential characteristic of Relay

4. Basic Considerations for Transformer
Differential Protection
•Correction for possible phase shift across the
transformer windings (phase correction)
•The effects of the variety of earthingand winding
arrangements (filtering of zero sequence currents)
•Correction for possible unbalance of signals from
current transformers on either side of the windings
(ratio correction)
•The effect of magnetising inrush during initial
energisation (5
th
Harmonic)
•The possible occurrence of over-fluxing (2
nd
Harmonics)

5. Differential 87

6. Differential 87
87T-Transformer Differential
87G-Generator Differential
87L-Line Differential

7. Tap to Define
Transformer, CTs
Etc
Tap to Relay
Characteristic
Harmonics
Setting for
Inrush, Over
Fluxing
Differential 87T

8. •Transformer setting interface in Differential 87
Fig:Over All Transformer setting interface
Transformer
Setting and
Vector Group
87T-Transformer setting

9. 87T-Transformer setting
•Transformer vector group selection setting
Fig:Transformer Vector group Selection Interface

10. 87T-Transformer setting
•Transformer setting with vector Group
Fig:Transformer rating tab with Vector group data

11. 87T-Grounding CT setting
•Grounding CT Setting
Fig:Grounding CT

12. 87T-CT setting
•Current Transformer setting
Fig:CurrentTransformer setting

13. 87T Interposing CT setting
Fig:Interposing CurrentTransformer setting

14. 87T Internal Current Compensation
Fig:Interposing CurrentTransformer setting

15. 87T-Relay Characteristic
Single Slop
Characteristic
Dual Slop Characteristic
ABB, SEL, AREVA
Dual Slop with Knee
Point Characteristic
Reyrolle Duobias
Characteristic
GE T60 Universal Relay
Characteristic

16. 87T-Relay Characteristic-Slope
Single Slope
Characteristic
Dual Slope
Characteristic
ABB, SEL, AREVA

17. 87T-Relay Characteristic-Slope
Dual Slop with
Knee Point
Characteristic
ReyrolleDuobias
Characteristic

18. 87T-Relay Characteristic-Slope
GE T60
Universal Relay
Characteristic
IBiasFormula

19. Differential Module Differential relay
characteristic display
•Based on the setting of the
Relay, a differential characteristic
will draw.
•To draw characteristics, Relay
Template also available
•Including more relays in library.
Fig:Differential Characteristic

20. 87T Harmonics testing interface
Fig7:Harmonics testing interface

21. Differential Module Harmonic characteristic
Fig:Differential Characteristics
Harmonics
selection
Setting for
Characteristic

22. Differential Module Harmonic characteristic
Fig:Differential Characteristics
Harmonics
selection
Setting for
Characteristic

23. Test Selection
•Click and Test: Click on Characteristic of relay
and fault will inject to relay and trip will
recorded. This test can conducted one by one.
•Verify Curve: In this test, Software
automatically check whole characteristic of
relay.
•Harmonics Restraint: Testing of Harmonics
effect on the relay. In this test, software will
find out exact boundary in between tripping
and Non Tripping Zone.
•Trip Time Test:in this test, software verify trip
time of the relay with deviations
•Stability Test: In case, if fault is outside
protection zone, relay should not trip. This
feature is verify by stability test

24. Test Selection_Verify Curve
Automatic test
point selection
Manual Test
point selection
by click on graph

25. Test Selection_Harmonics Restraint

26. Test Selection_Trip Time Test

27. Test Selection_Verify Curve
Automatic test
point selection
Manual Test
point selection
by click on graph

28. Test
•After selection of test points, run the
test and store all tests into results

29. Result
•Now save the test and print test report.

30. Report in Differential 87
Fig:Different report view

31. Report in Differential 87
Fig:Different report views

32. Report in Differential 87
Fig:Different report views