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The circuit breaker is composed of internal accessories and external accessories. The internal accessories include auxiliary contacts, alarm contacts, shunt releases and undervoltage releases. External accessories include electric operating mechanism, rotary operating handle, extension handle and handle locking device. This article focuses on external attachments.

A circuit breaker is a switching device capable of closing, carrying and breaking the current under normal circuit conditions and closing, carrying and breaking the current under abnormal circuit conditions within a specified time. Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. The external accessories of the circuit breaker are described below.

Circuit breakers can be used to distribute electrical energy, start asynchronous motors infrequently, and protect power lines and motors. They can automatically cut off the circuit when they experience serious overload or short-circuit and under-voltage faults. Their functions are equivalent to fuse switches. In combination with over-temperature and under-temperature relays. In addition, it is generally not necessary to change parts after breaking the fault current. At present, it has been widely used.

Electric operating mechanism
This is an accessory for long-distance automatic opening and closing circuit breakers. There are two types of electric operating mechanisms: electric motor operating mechanism and electromagnet operating mechanism. For 400A and above circuit breakers, the electromagnet operating mechanism is suitable for circuit breakers with a rated current of 225A and below. The position of the internal cam is used to achieve closing and opening. When the circuit breaker is operated by the electric mechanism, the circuit breaker should be reliably closed at any voltage between 85% and 110% of the rated control voltage.

Rotating operation handle
It is suitable for plastic case circuit breakers. A mechanism for rotating the operation handle is installed on the cover of the circuit breaker. The rotating shaft of the handle is installed in the matching hole of the mechanism. The handle is installed on the shaft head exposed on the door of the complete set of devices, and the round or square seat of the handle is fixed on the door with screws. This installation allows the operator to turn clockwise or counterclockwise through the handle Make sure the circuit breaker is closed or opened. At the same time, turning the handle can ensure that the cabinet door cannot be opened when the circuit breaker is closed; only when the handle is turned on or off, the door of the switch board can be opened. In an emergency, when the circuit breaker is in the "closed" state and the door panel needs to be opened, the red release button on the side of the turning handle seat can be pressed.

Extension handle
The extension handle is an external extension handle, which is directly installed on the handle of the circuit breaker. It is generally used for large capacity circuit breakers of 600A and above for manual opening and closing operations.

Handle locking device
The device is provided with a clip on the handle frame, a hole is punched in the handle and then locked with a padlock. It is mainly used for closing the circuit breaker.

In the working state, other people are not allowed to open and cause a power outage, or when the load-side circuit of the circuit breaker needs to be repaired or is not allowed to be energized, to prevent people from closing the circuit breaker by mistake.