140G Molded Case Circuit Breakers (MCCBs)

Allen-Bradley bulletin 140G current-limiting molded case circuit breakers (MCCBs) are rated to open in less than half of a cycle under fault conditions. This performance limits the let-through energy, providing enhanced protection for downstream components. In addition, per UL508A SB4, panel designers can use a current limiting circuit breaker’s rating to calculate overall panel/branch-circuit short circuit current ratings without having to test the specific components in combination.

MCCBs provide thermal overcurrent protection and shortcircuit protection. These devices provide this protection by using mechanical means with heater elements, or by using electronics to detect current flow and model the associated heat generated by the current. When electronic MCCBs are applied, the ability to adjust the thermal trip rating to shape the trip curve is available and the result is that there are fewer trip units required to cover a wider range of current. Note: while a trip unit may have the capability of protecting the current range, in many cases a rating plug is used to limit the range of adjustability.

These current limiting-rated MCCBs are available in three frame sizes:

• 140G H-Frame – 65 kA and 100 kA @ 480V
• 140G J-Frame – 65 kA and 100 kA @ 480V
• 140G K-Frame – 65 kA and 100 kA @ 480V

Because they are based on our standard 140G MCCBs, the current limiting
versions share the wide-range of available accessories. They are available as both completely assembled MCCBs and as components.

140G/140MG Features

• Interrupting capacity from 25 to 150 kA allows a single unit to address many applications, thereby reducing the number of different products to be specified
• Electronic trip units available from 25 to 3000 A
• Wide range of operating mechanisms to fi t with a variety of panel configurations
•  Short circuit current rating (SCCR) coordination with Allen-Bradley contactors, overload relays and motor starters

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