GE MiCOM P40 Agile Technical Manual

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Application Notes P44x/EN AP/Hb6MiCOM P40 Agile P442, P444 (AP) 5-21S >5 x (10% x Vn x 20% x In x cos (85°)This sum is calculated on five successive samples.the RCA angle of the delta algorithms is equal to 60° (-30°) if the protected line is not seriecompensated (otherwise RCA is equal to 0°).2.2.5 Phase SelectionPhase selection is made on the basis of a comparison between the transition values for thederivatives of currents IA, IB and IC:∆I'A, ∆I'B, ∆I'C, ∆I'AB, ∆I'BC, ∆I'CANote: The derivatives of the currents are used to eliminate the effects of the DC currentcomponent.Therefore:∑ +≥∆= 400iAAN )²'(S nninI ∑ +≥∆= 400iAB )²'(S nninABI∑ +≥∆= 400iBBN )²'(S nninI ∑ +≥∆= 400iBC )²'(S nninBCI∑ +≥∆= 400iCCN )²'(S nninI ∑ +≥∆= 400iCA )²'(S nninCAIThe phase selection is valid if the sum (SAB+SBC+SCA ) is higher than a threshold. This sum isnot valid if the positive sequence impedance on the source side is far higher than the zerosequence impedance. In this case, the conventional algorithms are used to select the faultedphase(s).Sums on one-phase and two-phase loops are performed. The relative magnitudes of thesesums determine the faulted phase(s).For example, assume:If SABBCCA and If SAB<BC, the fault has had little effect on the loop A to B. IfSANBNCN , the fault declared as single phase fault C.If the fault is not detected as single-phase by the previous criterion, the fault conditions aremulti-phase.If SAN BNCN and If SAB<BC, the fault is B to C.If SAN BNCN and If SAB≈SBC≈SCA and if SAN≈SBN≈SCN , the fault is three-phase (the faultoccurs on the three phases).2.2.6 SummaryA transition is detected if ∆I > 20% x In or ∆V >10% x VnThen three tasks are starting in parallel:• Fault confirmation: ∆I and ∆V (3 consecutive samples)• Faulty phase selection (4 consecutive samples)• Fault directional decision (5 consecutive samples)