Improvement of Thermal Stability in MCCB Frame-1

Abstract

The use of new technology is increasing today more than it did a decade ago. It will cause penetration into the Power grid and stress on both commercial and industrial equipment. Commercial and industrial machinery costs a lot of money, so it is important to protect it from any power system disturbances. The protecting devices' design must be good enough to defend the equipment and isolate it from the system if any undesirable events affect the equipment's supply. An MCCB must have the ability to break the circuit to protect against overload and short circuits happening in the power system with the least amount of energy loss, if possible, for the breaker to function properly for a longer period. MCCB offers the necessary robustness operation with a variety of current rating capacities. Current is constant in the breaker, so temperature rise, and voltage drop occur in the breaker mainly depend upon the internal resistance offered by the current path. As the breaker is in continuous operation if current loading is increased onto the breaker, then the temperature also rises in the breaker. The body of the breaker has its limitation for withstanding the temperature rise so beyond that limit breaker may be damaged and it further leads to its impact on the other surrounding machinery as well. It is necessary to control temperature rise occurring in the breaker and this only happens by controlling the value of the milli volt drop occurring in the breaker. Therefore, in the worst installation condition of machinery or breaker temperature should not exceed the pre-defined limits.