The protective unit of circuit breaker MUST fulfill:
- Instantaneous trip setting Im < Iscmin for a circuit-breaker
- Fusion current Ia < Iscmin for a fuse
The protective unit (or device) must satisfy the two conditions:
- Its fault-current breaking rating must be greater than Isc, the 3-phase short-circuit current at its point of installation.
- Elimination of the minimum short-circuit current possible in the circuit, in a time tc compatible with the thermal constraints of the circuit conductors, where:
.
EEP has published tool which was designed by mr. Jignesh Parmar. The tool is in form of MS Excel Spreadsheet and covers calculations of tripping setting of circuit breaker.
Spreadsheet is free for download.
Subscribe to receive more download updates.
Related electrical guides & articles
Edvard Csanyi
Hi, I'm an electrical engineer, programmer and founder of EEP - Electrical Engineering Portal. I worked twelve years at Schneider Electric in the position of technical support for low- and medium-voltage projects and the design of busbar trunking systems.I'm highly specialized in the design of LV/MV switchgear and low-voltage, high-power busbar trunking (<6300A) in substations, commercial buildings and industry facilities. I'm also a professional in AutoCAD programming.
Profile: Edvard Csanyi
Circuit breaker formula has been given using it I have setting circuit breaker tripping with ms excel spreadsheet. for that protective unit of circuit breaker must be filled up.