Frame circuit breakers are widely used in low-voltage power distribution systems because of their compact and durable structure, large current, strong breaking capacity, and rich protection functions. Now almost all low-voltage main distribution cabinets use frame circuit breakers. The circuit breaker has a compact structure and can be installed in mainstream cabinet-type power distribution cabinets. There are two main installation methods: fixed and drawer.
The main body of the fixed frame circuit breaker is directly connected to the copper bar of the power distribution cabinet. If the circuit breaker needs to be overhauled, it is necessary to cut off the front circuit breaker or even the high-voltage cabinet at the front of the transformer. Therefore, most designers will design an isolating switch at the front end of the fixed frame circuit breaker for maintenance of the isolated power supply. There is a frame outside the withdrawable circuit breaker, which is connected with the bus bar of the power distribution cabinet. The main body of the circuit breaker can be shaken in and out by the mechanism at any time, and the circuit breaker can be shaken out during maintenance without power failure.
There are two types of wiring terminals behind the circuit breaker, vertical and horizontal, which should be marked when purchasing, and can be selected according to actual needs. Frame circuit breakers have strong short-circuit segmentation capabilities, and circuit breakers with a capacity of 150 kiloamps are now available. Thirdly, the short-circuit breaking capacity has a great influence on the price, so you can choose a suitable specification according to the capacity of the front-end transformer and the expected short-circuit current at the low end.
The logic controller is the brain of the air circuit breaker, and various protection parameters are adjustable. Basically there are two-level protection type (long overload delay, short short-circuit delay), three-level protection type (long overload delay, short-circuit short delay and instantaneous short-circuit) and four-level protection type (long overload delay, short-circuit short delay) Time, short-circuit transient and ground fault protection). There are also some extended functions, such as measurement, metering and communication. Generally, the logic controller is modular and independent of the circuit breaker itself. In many cases, the logic controller can be replaced to expand the protection function of the circuit breaker, thereby saving the overall replacement cost of the circuit breaker.
