All Air Circuit Breakers (ACB) can be operated either electrically or manually. There are two operation methods available.

Electrical Operation

The electrical operation of an air circuit breaker is initiated by an automatic control signal produced in the main switch board or by manual operation of the corresponding one of breaker control switches; these control switches are located on the synchro panel of the switch board and marked “ACB CONTROL”. Pull the breaker control switch knob towards you and turn it clockwise to close the breaker, or anticlockwise to open the breaker. As soon as the knob is released, it returns to the central position and is locked in this position.

Manual Operation

Direct manual operation of the air circuit breaker is recommended only for inspection and maintenance. Pull the manual control lever of the breaker towards you to close and press the trip button in the breaker front to open.

Molded Case Circuit Breakers (MCCB)

All other circuit breakers used for distribution and load circuit protection purposes are molded case circuit breakers. These breakers are automatically tripped, should overload or short circuit develop in their load circuits; the re-establishment of connection can be made easily and safely without need for replacement of elements such as fuses.

See Also: Main Switch Board Safety

See Also: Main Switch Board