Principle of abb leakage switch

The operation principle of the leakage switch is: there are two groups on an iron core: An input current winding and an output current winding, when there is no leakage, input current and output current are equal, and the vector sum of two magnetic flux on the core is zero, the potential will not be induced in the third winding, otherwise the third winding will be induced voltage formation, after amplification to promote the actuator, make the switch trip.

In front of the UPS leakage protection switch, although the UPS no leakage phenomenon, but because of the harmonic in the core of the magnetic flux vector and due to the magnetic hysteresis of the core can not be zero, so there is a similar illusion of leakage, the leakage protector frequently trip.

Leakage will live line zero line at the same time through an O-ring as a primary, secondary with N turns output to promote an electromagnetic mechanism, electromagnetic mechanism action is tripping. The principle is that under normal circumstances, the current on the live line and the neutral line flows into is equal to the outflow, so the induction out of the secondary voltage is zero, when the live line or the neutral line has a line to ground resistance or short circuit, the current on the live line and the neutral line voltage difference, through the secondary induction, when to a certain difference will promote the electromagnetic mechanism out of the main loop.

In normal operation, no leakage current except the working current in the circuit passes through the leakage protector. At this time, the current flowing through the zero-sequence transformer (detecting transformer) is equal in magnitude and opposite in direction, and the sum is zero. The induced flux in the transformer core is also equal to zero, and the secondary winding has no output. When leakage occurs between the protected electrical device and the line or someone is electrocuted, there is a ground fault current, which makes the current flow through the detecting transformer and the sum is not zero. Magnetic flux occurs in the inducted transformer core, and the secondary winding generates induced current, which is output after amplification, so that the leakage trip device drives the automatic switch trip to achieve the purpose of leakage protection.