Thermal and Magnetic Yield Improvement in New Range of Moulded Case Circuit Breaker (MCCBs) of Higher Rating (100 – 160 A) with VTVM

Abstract

Moulded case circuit Breaker (MCCB) is device designed to protect low voltage distribution system from both overload and short circuit conditions. Thermal-magnetic release MCCBs is favorable for the protection of such system because of their simple, compact and economical design. However, there are various concerns associated with thermal-magnetic release MCCBs, like the failure in thermal and magnetic tripping. Such abnormal performance may cause damage to the system where it is employed and also drop down the overall yield of the product which greatly affects the production cycle. It is essential to analyze the root cause of such abnormal tripping action in prolong overload and short duration over-current conditions. The proposed work emphasis on the improvement of thermal and magnetic yield of new range of MCCBs by improving the current process and design based upon data analysis to curb the failure rate. DFSS tools are used for achieving the objective of the proposed work. Improvement in first time yield (FTY) in thermal and magnetic performance of MCCB were observed for various ratings during trial run with modified process.