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Protection Riddle No.90 - Directional Earth Fault testing
I would like to know more about testing methods of Directional Earth fault Protection. Also mainly in which system Directional earth fault is mandatory?
Author : Pramod - From: India
Thu, May 24th, 2012 - 13:46
The overcurrent unit of a directional relay should be checked similarly to the overcurrent relay, with the directional unit blocked closed. The directional relay should be tested for minimum pickup, maximum torque angle, contact gap, and clutch pressure. If the phase power supply is not available, the directional unit can be tested by applying single-phase voltage and current in phase. Usually, this test will give large variations in in-phase pickup, because of in-phase angle being far different from maximum torque angle. 
Author : Hamid - From: Iran
Sat, October 13th, 2012 - 16:51
When paralell feeders are taken from two substations to a station directional O/C and E/F relays are required to avoid supply interruption to the station on one feeder fault 
Author : V.K.Nambiathiri - From: India
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