MCB (Miniature Circuit Breaker)
What is MCB ?
MCB is an electromechanical device designed to protect an electric circuit from overcurrent (an electrical fault caused by either overload or short circuit.
Three principles characteristics for MCB
Overload Current Rating (Amperes)
Overload occurs when too many appliances are put on one circuit and draw more electrical current than that circuit and cable are designed to take. This could occur in the kitchen, for example when too many appliances are all in use simultaneously. The MCB on this circuit cuts power thus preventing overheating and fire in the cable and terminals.
Short Current Rating (Kilo Amperes)
Short Circuit is the result of a fault somewhere in the electrical circuit or appliance. It occurs when there is a direct connection between the live and neutral conductors. Without the resistance provided by the normal circuit integrity, electrical current rushes around the circuit in a loop and multiplies the amperage by many thousand times in just milliseconds.
The 'Tripping Curve' of an MCB allows for the real world and sometimes entirely necessary, surges in power. In commercial environments for example, large machines usually require an initial surge of power in excess of their normal running current to overcome the inertia of large motors. This brief surge lasting just seconds, is allowed by the MCB as it is safe to do so for this very short amount of time.