EF Compensation Question
EF Compensation Question
(OP)
Hi
Could someone define for me what is meant by an uncompensated (conversely compensated) distance relay please? Is there any definition defined somewhere? From various sources I have come to understand that a compensated distance relay is one which modifies the current component fed to the measuring element so that the apparent impedance measured is the line positive sequence impedance to the fault point, Z1L. Classicaly the compensated current is Ic = IA + 3I0*IR for an A-phase fault where IR = IA + IB + IC. Where IA = IR this becomes 1 + K0.
Naturally the fault resistance is also affected by Ic.
1. If a relay does not modify the current fed to the measuring element, but instead enlarges the quadrilateral resistive and reactive reach so as to prevent underreaching with EF's is it a compensated relay?
2. Someone told me that the SEL distance relays are uncompensated but I do not think so after reading the instruction manual of one of them.
But I think it comes down to what is meant by an uncompensated relay.
Thanks.
Could someone define for me what is meant by an uncompensated (conversely compensated) distance relay please? Is there any definition defined somewhere? From various sources I have come to understand that a compensated distance relay is one which modifies the current component fed to the measuring element so that the apparent impedance measured is the line positive sequence impedance to the fault point, Z1L. Classicaly the compensated current is Ic = IA + 3I0*IR for an A-phase fault where IR = IA + IB + IC. Where IA = IR this becomes 1 + K0.
Naturally the fault resistance is also affected by Ic.
1. If a relay does not modify the current fed to the measuring element, but instead enlarges the quadrilateral resistive and reactive reach so as to prevent underreaching with EF's is it a compensated relay?
2. Someone told me that the SEL distance relays are uncompensated but I do not think so after reading the instruction manual of one of them.
But I think it comes down to what is meant by an uncompensated relay.
Thanks.





