1. Earthfault Detection Requirements for a transient-relay:
High ohmic earthfaults up to some kOhm
Restriking faults
Intermittent faults
Directional
Independence from the moment of ignition

2. Earthfault Detection Transient behaviour of an earthfault
qu - algorithm
Low ohmic earthfault
High ohmic earthfault
Intermittent faults
Field tests
Summary

3. Beginn of an Earthfault
Change of the voltages during the charging process

4. Discharge of the Faulty Phase

5. Charge of the Healthy Phases

6. Simplified Equivalent Circuit

7. Low Ohmic Earthfault
Two healthy feeders
Faulty feeders

8. qu – algorithm

9. High Ohmic Earthfault

10. qu – algorithm

11. Restriking Fault

12. Restriking Fault

13. Field Tests

14. Field Tests

15. Field Tests

16. Field Tests

17. Field Tests

18. Field Tests

19. Field Tests

20. Summary Detection of high ohmic transients is now possible
Direction of the earthfault can be detected also during restriking and intermittent earthfaults
The sensitivity can be selected direct as function of the capacitive current Ice
Restriking faults can occur at ⇨ cable networks ⇨ poles made of concrete ⇨ configurations with an air gap ⇨ configurations with time-invariant resistance