Improvement in Magnetic consistency of Thermal Magnetic Release of 630A frame MCCB

Abstract

MCCBs are the most employed protection devices in the industry. The main pur- pose of MCCB is to trip or open the circuit in case of short circuit or over-load in the circuit. The Trip unit of MCCB is known as Release assembly. It contains a bimetallic strip and electromagnet i.e. Fixed and moving magnet to sense overload in the system. In any abnormal condition when current exceeds the rated value, trip unit senses it and gives command to the mechanism to open and break the contact system. Existing 630A frame release assembly shows inconsistency during calibration of magnetic release. Release assembly contains fixed magnets and torsion springs for calibration which will be analyzed on FEA tools to realize the limitations and scope for design im- provements. Based on the outcomes of detailed study and simulation results, new concepts for the release of the MCCB will be developed. Pro-E software will be used for 3D modelling of the proposed designs. Prototypes of the proposed design will be validated by practical testing of 630A Frame MCCB. On successful comple- tion of design validation, proposed design will be finalized to improve the calibration consistency.