Analysis and improvement in repulsive force of 630 A frame Moulded Case Circuit Breaker (MCCB)

SummaryMoulded Case Circuit Breaker (MCCB) is a protective device used for low voltage protection in the range of 12–1250A. It is having fast breaking and making ability due to special contact structure. In case of transformer it is generally placed in secondary side and in case of motor protection it is used as backup protection. The existing design is suffering from chattering of contact tip which lead to erosion and in turn affect electrical life. It also reduces interrupting/breaking capacity of MCCB. In this paper, detailed study of the factors and constraints related to repulsion threshold current (Irp) and consistency of magnetic release for 630 A MCCB is carried out using Finite Element tool JMAG to find out limitations and scope of design improvements in existing design. The proposed suggestion is validated by testing