As an important switchgear in low-voltage complete switch cabinets and low-voltage distribution boxes, low-voltage circuit breakers are used in almost every switch cabinet and distribution box. Its main function is equivalent to the combination of knife switch, fuse, thermal relay, overcurrent relay and undervoltage relay. It can be used to connect and break the load circuit, and it can also be used to control the motor that starts infrequently. It is an existing manual switch. It is a switching device that can automatically perform under-voltage, loss-of-voltage, overload and short-circuit protection. It is one of the important electrical appliances that can play a protective role in distribution boxes and distribution cabinets. Today, Jintaiheng, a Shanxi distribution box manufacturer, will introduce the precautions for the installation and maintenance of low-voltage circuit breakers.
Low-voltage circuit breakers refer to switching appliances that can make, carry and break current under normal circuit conditions, and can also make, carry and break current for a certain period of time under specified abnormal circuit conditions (overload, short circuit). Move the air switch.
A self-check should be performed first before installing circuit breakers for low-voltage distribution boxes. Check whether the specifications of the circuit breaker meet the requirements, and whether the operation of the mechanism is flexible and reliable; at the same time, the insulation resistance of the circuit breaker should be measured, and its resistance should not be less than 10MΩ, otherwise it should be dried.
When installing low-voltage circuit breakers in low-voltage distribution boxes and switch cabinets, pay attention to the following points:
1. It must be installed in the specified direction, otherwise it will affect the accuracy and on-off capacity of the release seat.
2. The installation should be stable, otherwise the molded case circuit breaker will affect the tripping action, while the drawer circuit breaker may affect the reliability of the secondary circuit connection.
3. During installation, there should be a certain space for flying foxes on the upper part of the arc chute to avoid flying foxes. For molded case circuit breakers, the incoming line end should be covered with 200mm long insulation, and sometimes arc clapboards should be installed between the phases of the incoming line end.
4. The incoming wire of the power supply should be connected to the terminal (upper busbar) on one side of the arc extinguishing chamber, the outgoing wire connected to the load should be connected to the terminal of one side of the breakout unit, and an appropriate cross-section of the connecting wire should be selected so as not to affect the over-current. The protection of the current release.
5. The operating mechanism of the molded case circuit breaker has been debugged before leaving the factory, and the operating mechanism shall not be adjusted arbitrarily when disassembled.
6. Molded case circuit breakers with plug-in segments should be installed in the metal box (only the operating handle is exposed) to avoid accidents caused by operators touching the terminals.
7. All circuit breakers with grounding screws should be grounded reliably.
