FIELD: electricity.
SUBSTANCE: in this method negative-sequence current of the lines under protection is used as controlled electrical quantity, it is educed by measurement and calculation as a symmetrical component of three-phase currents in the system lines. Negative-sequence current is measured continuously before and upon occurrence of ground fault for all lines under protection. Increment of negative-sequence current is used as an input parameter for the protection operation, it is determined at once upon fault occurrence by subtraction of pre-recorded value of negative-sequence current from its actual value.
EFFECT: improving selectivity and reliability of protection.
1 dwg
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