PHASE CURRENT DIFFFERENTIAL: Phase A Phase B Phase C HMI HMI HMI pick P/U D/O P/U D/O P/U D/O up Idiff Idiff (A) = (A) (A) (A) (A) (A) 87LPP = IBT = ICT IAT (sec A) (sec A) (secA) Pick up Accuracy: ±3% ±0.01 INOM, According to the Catalogue for manual # 20130311 Page 56 Phase A Phase B Phase C HMI HMI HMI pick P/U D/O P/U D/O P/U D/O up Idiff (A) (A) (A) = (A) (A) = (A) = IAT IBT ICT (secA) (sec A) (sec A) NEGATIVE/ ZERO SEQ CURRENT DIFFERENTIAL: 87L2 seq diff 87LG- zero seq diff –Negative Expected HMI HMI 87L2P/ pick up display display 87LGP 87L2P or P/U (A) D/O (A) P/U (A) D/O (A) Idiff= 3I2T Idiff= 3I0T 87LGP (pri A) (Pri A) Note: For 87L2 /87LG sensitivity a single current shall be injected. In this case the negative sequence (I2) or zero sequence (I0) current is equal to 1/3* Iph. But the relay compares 3 x I2_injected and 3 x I0_injected with the 87L2P / 87LGP thresholds. TIMING TEST:
PHASE CURRENT DIFFFERENTIAL: pick up 87LPP Phase A Phase B Phase C P/U (A) HMI = IAT (secA) D/O (A) P/U (A) HMI Idiff = IBT (sec A) D/O (A) P/U (A) HMI Idiff = ICT (sec A) D/O (A) Pick up Accuracy: ±3% ±0.01 INOM, According to the Catalogue for manual # 20130311 Page 56 pick up Phase A Phase B Phase C P/U (A) HMI Idiff = IAT (secA) D/O (A) P/U (A) HMI = IBT (sec A) D/O (A) P/U (A) HMI = ICT (sec A) D/O (A) NEGATIVE/ ZERO SEQ CURRENT DIFFERENTIAL: 87L2P/ 87LGP Expected pick up 87L2P or 87LGP 87L2 –Negative seq diff 87LG- zero seq diff P/U (A) HMI display Idiff= 3I2T (pri A) D/O (A) P/U (A) HMI display Idiff= 3I0T (Pri A) D/O (A) Note: For 87L2 /87LG sensitivity a single current shall be injected. In this case the negative sequence (I2) or zero sequence (I0) current is equal to 1/3* Iph. But the relay compares 3 x I2_injected and 3 x I0_injected with the 87L2P / 87LGP thresholds. TIMING TEST:
sel-411l_-_line_distance___differential.docx