Allen Bradley 140G MCB

About 140G MCB

The Allen-Bradley/Rockwell Automation 140G MCB series is a series of molded case circuit breakers. According to the National Electrical Manufacturers Association (NEMA), a circuit breaker is a device designed to open and close a circuit by non-automatic means, and to open the circuit automatically at a predetermined overcurrent level without injury to itself when it is properly applied within its rating. The 140G MCB circuit breakers employ different methods to control the operating mechanisms. These methods include stored energy operation, dependent manual/power operation, and independent manual/power operation. When breakers in the 140G MCB family encounter an overcurrent, they can use instantaneous, inverse time delay, and definite time delay overcurrent releases. All these breakers from the Allen-Bradley 140G series of molded-case circuit breakers come with a frame rating of 125 Amps and an interrupting capacity that goes from 25 to 65 kA.

The Allen-Bradley 140G MCB series of circuit breakers are CCC, UL, and CSA certified since they comply with international standards such as the UL, CSA, and IEC standards. Since these circuit breakers have molded cases, they provide short circuit and thermal overcurrent protection by using either mechanical or electronic means. Note that the mechanical means use heater elements to detect the current flow and model the associated heat generated by the current. Additionally, molded case circuit breakers in this family feature either fixed or adjustable trip units. Whether they use fixed or adjustable magnetic and thermal trip units, the motor current rating of these circuit breakers should be less than or equal to 250% of the motor’s full-load ampere rating, or less than or equal to 300% for motors with a current of less than or equal to 100 amperes if the circuit trips on startup. Also, a circuit breaker in the 140G MCB series can be used with a motor current rating of less than 400% for motors with a current rating of more than or equal to 100 Amps if the circuit breaker trips on startup. The safety features of these breakers are capable of preventing accidents such as fires and explosions due to over-current or the overheating of conduits.