摘要:
It is desirable to provide remote digital protection of distribution transformers. A protection system is disclosed which is able to detect increases in positive sequence current and to detect increases in negative sequence current resulting from unbalanced disturbance on a distribution cable feeding a transformer. The triggering of a circuit breaker (19) is then initiated to isolate the supply cable (10) in response to a detected increase in negative sequence current only if there is a simultaneous detected increase in the positive sequence current in excess of a respective threshold increase.
摘要:
It is desirable to provide remote digital protection of distribution transformers. A protection system is disclosed which is able to detect increases in transient D.C. current flowing in the respective phases of a distribution cable (10) feeding a transformer and also to detect increases in other selected functions of supply parameters for identifying and quantifying a fault current flowing in the distribution cable (10). Increases in these other functions are analysed to identify whether the increases indicate a fault current. Any such fault current can then be quantified and the triggering of a circuit breaker (19) initiated to isolate the supply cable on identifying a fault current. The circuit breaker (19) is not triggered for any increases in the other functions for as long as there is a detected increase in D.C. current in any phase.
摘要:
It is desirable to provide remote digital protection of distribution transformers. A protection system is disclosed which is able to measure parameters of a supply to a distribution cable (10) to a distribution transformer to provide time related values for the positive sequence current, voltage and phase angle. Time related values for the susceptance of the distribution cable (10) and load connected thereto can then be calculated, and monitored to detect increases in negative susceptance. The triggering of a circuit breaker (19) is then initiated to isolate the distributor cable (10) if the increase exceeds a predetermined thershold increase.
摘要:
It is desirable to provide remote digital protection of distribution transformers. A protection system is disclosed which is able to measure parameters of a supply to a distribution cable (10) to a distribution transformer to provide time related values for the positive sequence current, voltage and phase angle. Time related values for the susceptance of the distribution cable (10) and load connected thereto can then be calculated, and monitored to detect increases in negative susceptance. The triggering of a circuit breaker (19) is then initiated to isolate the distributor cable (10) if the increase exceeds a predetermined thershold increase.
摘要:
It is desirable to provide remote digital protection of distribution transformers. A protection system is disclosed which is able to detect increases in positive sequence current and to detect increases in negative sequence current resulting from unbalanced disturbance on a distribution cable feeding a transformer. The triggering of a circuit breaker (19) is then initiated to isolate the supply cable (10) in response to a detected increase in negative sequence current only if there is a simultaneous detected increase in the positive sequence current in excess of a respective threshold increase.
摘要:
It is desirable to provide remote digital protection of distribution transformers. A protection system is disclosed which is able to detect increases in transient D.C. current flowing in the respective phases of a distribution cable (10) feeding a transformer and also to detect increases in other selected functions of supply parameters for identifying and quantifying a fault current flowing in the distribution cable (10). Increases in these other functions are analysed to identify whether the increases indicate a fault current. Any such fault current can then be quantified and the triggering of a circuit breaker (19) initiated to isolate the supply cable on identifying a fault current. The circuit breaker (19) is not triggered for any increases in the other functions for as long as there is a detected increase in D.C. current in any phase.