For protective relaying, can differential current protection be used for phase-to-phase faults?

Thread Starter

Mountain_cat

Joined Jul 11, 2016
9
If a phase to phase fault happens on a cable, then current differential, phase comparison and directional relays wont be helpful because the measured values at the start and end of the cable will be the same, correct?

So this leaves only the over current relay protection scheme as a viable option for phase to phase faults?

Am I correct in this thinking?
 

MrAl

Joined Jun 17, 2014
11,389
Hi,

If you draw a diagram of your circuit and what is being measured now and what you want to measure in the future to improve the design that would help understand what you are after.

For example, if you measure current in a line and the phase of the source changes and there is no load then yes you cant detect a change in current. But if there is a load then you should be able to detect that change in line current. Just one example as i am not sure what you have there exactly and dont know what kind of load you have.
 

YZee

Joined Aug 11, 2016
1
Hi

In protection design you would not use a differential protection scheme for a transmission line. The differential protection scheme is used for protecting equipment such as a transformers.

To protect a transmission line you would use protection schemes designed for that purpose. This could include using overcurrent relays or zone/distance relay.
 
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