There is provided an arc extinguishing unit of a molded case circuit breaker having a structure in which grids and side plates forming an arc chamber are coupled in an inserted manner, facilitating an operation, and intervals of grids are uniformly maintained and a configuration of the grids is not damaged, thus maintaining stable performance and allowing for maintenance. The method allows for removing at least a portion of an originally assembled coil support on a spider structure of the machine. The power supply system also includes a second UPS device coupled to receive power from the AC power line. Also, a machine for processing food products and containing such a tool.