| 摘要 |
PCT No. PCT/DE95/00581 Sec. 371 Date Jan. 2, 1997 Sec. 102(e) Date Jan. 2, 1997 PCT Filed Apr. 24, 1995 PCT Pub. No. WO95/30264 PCT Pub. Date Nov. 9, 1995A differential current protective device for a transformer arranged in a multi-phase power supply system and having at least one star-connected winding arrangement with a grounded star point. The differential current protective device receives currents proportional to the system currents via current transformers provided on the high and low voltage sides of the transformer. A computing circuit of the protective device determines a differential phase-related current from the currents measured, taking into account a current parameter that corresponds to the zero system current based on the phase and whose intensity is monitored. The differential current protective device includes an auxiliary current transformer having its primary winding in the connection between the star point and ground. The computing circuit processes the secondary current of the auxiliary current transformer as the current parameter corresponding to the zero system current.
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