RCCB’s working principle
Years of operating experience at home and abroad show that the promotion of the use of RCCB to prevent electric shock casualties, to avoid leakage caused by a fire accident, with obvious results. This article on the widely used RCCB to make some introduction to the working principle.
RCCB works: RCCB includes detection components (zero-sequence current transformer), the intermediate links (including amplifiers, comparators, releases, etc.), the implementation of components (main switch) and several other components of the test element . Three-phase four-wire power supply system leakage protection schematic diagram. TA is the zero-sequence current transformer, GF is the main switch, TL is the main switch shunt release coil. In the protected circuit is working properly, there is no leakage or electric shock case, by Kirchhoff’s law shows that the current through the TA side of the phasor and equal to zero, that is: This TA secondary side does not produce induced electromotive force, leakage protection No action, the system to maintain normal power supply. When the circuit being protected or the electric shock occurs, due to the existence of the leakage current, the phase current through the primary side of the TA is no longer equal to zero and the leakage current Ik is generated. Alternating flux appears in the core. Under the action of alternating magnetic flux, there is induced electromotive force in the secondary coil of TL. The leakage signal is processed and compared through the intermediate link. When the predetermined value is reached, the main switch shunt release coil TL is energized to drive the main Switch GF automatically trip, cut off the fault circuit, in order to achieve protection. The same applies to the earth leakage protector for single-phase circuits and three-phase three-wire systems