The influence of current transformer iron core saturation of protection analysis

Current transformer iron core saturation effect on protection analysis - 2019 03 - 30 15:05:36 1, the influence of current transformer iron core saturation of current protection current protection criterion: Ij is greater than the Ij in Iz type is into the secondary short circuit current value of the relay, Iz for current relay setting value. Current transformer iron core saturation, the secondary action of current Ij decrescent, refusing action, may cause this is especially significant in the current instantaneous fault protection. After serious saturation current transformer iron core, primary current all into excitation current, secondary induced current is zero, the current through the current relay is zero, protection device refused to move. 2, the influence of current transformer iron core saturation of busbar differential protection according to the characteristics of the current transformer iron core saturation, it fails, because the magnetic flux in core cannot mutate, current transformer iron core is not immediately enter the saturated zone, but there is a 3 & ndash; 5 ms linear transfer zone. When bus bar fault, differential element of differential current and fault voltage and current at the same time; When the bus protection fault zone, and a set of current transformer iron core saturation, differential element of differential current appeared later than fault voltage and current 3 & ndash; 5ms。