Circuit breakers offer various connection methods: front-panel, rear-panel, plug-in, and draw-out. Unless users specify otherwise, units are supplied with the front-panel configuration by default, as this is the most common connection method.
1. Rear-Panel Connection: The primary advantage of the rear-panel connection method 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 structural design, products are shipped from the factory pre-equipped with specialized mounting plates, mounting screws, and terminal screws in accordance with design specifications. A critical point to note is that, particularly for high-capacity circuit breakers, the reliability of electrical contact directly impacts the device's normal operation; therefore, installation must be treated with the utmost seriousness and performed strictly in accordance with the manufacturer's requirements.
2. Plug-in Connection: In this configuration, a dedicated mounting base for the circuit breaker is first installed onto the mounting panel of the complete switchgear assembly. This mounting base features six plug pins, while the circuit breaker's connection plate is fitted with six corresponding sockets. The mounting base may feature 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 both front-panel and rear-panel connections. However, since plugging and unplugging the unit requires a certain amount of manual force, the frame size current rating for plug-in products in China is typically limited to a maximum of 400A. This design effectively saves time spent on maintenance and replacement. During installation, it is essential to verify that the circuit breaker's plug pins are firmly seated and that the breaker itself is securely fastened to minimize contact resistance and enhance overall reliability.
3. Draw-out Connection: The insertion and withdrawal of the circuit breaker into and out of its housing 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-style contact structure. This design eliminates the need for the separate isolators typically required in fixed-mount configurations, thereby allowing a single device to serve a dual function and improving economic efficiency. Furthermore, this approach offers significant convenience for operation and maintenance while simultaneously enhancing safety and reliability. A particularly notable feature is that the main circuit contact blades within the draw-out chassis are designed to be interchangeable with the contact blades used in NT-type fuse-disconnectors.
