Circuit breakers feature several wiring methods: front-panel, rear-panel, plug-in, and draw-out types. Unless the user specifies otherwise, units are supplied with front-panel wiring as the default; indeed, front-panel wiring is the most common connection method.
(1) Rear-Panel Wiring: The primary advantage of rear-panel wiring is that circuit breakers can be replaced or repaired without the need for rewiring; one simply needs to disconnect the upstream power supply. Due to the unique nature of this structure, the product is supplied from the factory-in accordance with design specifications-complete with a dedicated mounting plate, mounting screws, and wiring screws. Particular attention must be paid during installation: since the contact reliability of high-capacity circuit breakers directly impacts their proper operation, installation procedures must be treated with the utmost seriousness and executed in strict compliance with the manufacturer's requirements.
(2) Plug-in Wiring: With this method, a dedicated mounting base for the circuit breaker is first installed onto the mounting plate of the complete switchgear assembly. The mounting base features six plug pins, while the circuit breaker's connection plate contains six corresponding sockets. The mounting base is equipped with either connection plates on its front face or bolts on its rear side, allowing the power supply and load cables to be pre-connected to the base. During operation, the circuit breaker is simply plugged directly into the mounting base. If a circuit breaker fails, the faulty unit can be easily unplugged and replaced with a functional one. This replacement process is faster and more convenient than that of front-panel or rear-panel wiring systems. However, since plugging and unplugging the unit requires a certain amount of physical effort, the frame current rating for plug-in products in my country is typically limited to a maximum of 400A. This design effectively minimizes the time required for maintenance and replacement. When installing a plug-in circuit breaker, it is essential to verify that the breaker's plug pins are firmly seated and that the unit is securely fastened; this ensures minimal contact resistance and enhances overall reliability.
(3) Draw-out Wiring: The insertion and withdrawal of the circuit breaker within its drawer unit are controlled by rotating a rocker handle either clockwise or counter-clockwise. Both the main power circuit and the secondary control circuit utilize a plug-in connection structure, thereby eliminating the need for the separate isolators typically required in fixed-mount systems. This design allows a single unit to serve a dual function, improving economic efficiency while offering significant convenience for operation and maintenance, as well as enhanced safety and reliability. Notably, the main circuit contact blades within the drawer base are designed to be interchangeable with the contact blades found in NT-type fuse-disconnectors; this feature allows for the direct insertion of a fuse unit to restore power in emergency situations.