LINE PROTECTION DEVICE FROM SINGLE-PHASE EARTH FAULTS IN NETWORK WITH INSULATED NEUTRAL WITH VOLTAGE OF 6-10 KV
Keywords:
current, neutral, network, protection, line, capacitance, transformer.Abstract
A device has been developed for protection the line from a single-phase earth fault in a network with isolated neutral that provides selectivity and operating speed at a single-phase earth faults through a transient resistance in case, additionally, if the capacitive current of the protected line is commensurate with the total current of the remaining lines. The developed device comprising the capacitors by number of phases connected in the junction of the primary windings of the main and additional zero sequence current transformers connected in series and having matching elements at the output, supplied with thyristor optocouplers, NAND logic elements connected in an RS-flip-flop circuit, transistor, performing the functions of the electronic key, optotiristor, which power electrodes commute the coil of a disconnection electromagnet of the line load breaker. A device has been developed for protection the line from a single-phase earth fault in a network with isolated neutral that provides selectivity and operating speed at a single-phase earth faults through a transient resistance in case, additionally, if the capacitive current of the protected line is commensurate with the total current of the remaining lines.
