SIPROTEC 4 7SJ63 Multifunction Protection Relay - Siemens

5 Overcurrent Protection / 7SJ63Typical connectionsConnection for compensated networksThe figure shows the connection of twophase-to-earth voltages and the V Evoltage ofthe open delta winding and a phasebalanceneutral current transformer for theearth current. This connection maintainsmaximum precision for directional earthfaultdetection and must be used in compensatednetworks.Figure 5/130 shows sensitive directionalearth-fault detection.Fig. 5/130Sensitive directionalearth-fault detectionwith directionalelement for phases5Fig. 5/131Sensitive directionalearth-fault detectionConnection for isolated-neutralor compensated networks onlyIf directional earth-fault protection is notused, the connection can be made with onlytwo phase current transformers. Directionalphase short-circuit protection can beachieved by using only two primary transformers.Fig. 5/132Isolated-neutral orcompensatednetworksSiemens SIP · 20065/131