Moulded case circuit breaker (MCCB) is one of the most common low-voltage electrical components. It can make and break rated current reliably and cut off the current automatically when the current exceeds the trip setting. Next, Tongyida will explain how to connect the moulded case circuit breaker and the wiring precautions.
Wiring method of moulded case circuit breaker
There are five wiring modes of MCCB, including front wiring, back wiring, inserting and pulling out (drawer) wiring and guide rail type. Before the circuit breaker is put into operation, carefully check whether the fixed connection part is firm and ensure that the operating mechanism is in a flexible state.
1. The wiring mode in front of the board is the default connection mode of the circuit breaker. If the wiring mode in front of the board is adopted, no special instructions are required. Before the circuit breaker is installed in the complete set of equipment, the user can directly connect the power line and load line on the connection plate of the circuit breaker base, and the wiring is fastened with screws.
2. Back board wiring means that when the circuit breaker is installed in a complete set of equipment, the power line and load line are connected to the connecting plate on the base of the circuit breaker through the bolts of the mounting plate. Its biggest characteristic is that the circuit breaker can be replaced or repaired without rewiring, only the front power supply can be disconnected.
3. Plug in connection refers to the installation of a mounting base with six sockets on the mounting plate of the complete set of equipment, which is used together with the six sockets on the connection plate of the circuit breaker.
4. The drawer type wiring is generally used for the installation of the universal circuit breaker. The in and out drawer of the circuit breaker is completed by clockwise or reverse rotation of the rocker. The plug-in structure is adopted in both the main circuit and the secondary circuit, and the necessary isolators for fixed installation are omitted. It can achieve two purposes for one machine, improve the economic efficiency, increase the safety and reliability, and bring about operation and maintenance at the same time Great convenience.
Precautions for wiring of moulded case circuit breaker
1. General circuit breaker equipment, there are power supply and load signs, in the actual wiring process, according to the above mark to go, do not connect the two reversed.
2. The control switch or protection line shall not pass through the current transformer. When the three-phase five wire system or single-phase three wire system is adopted, the protection line must be connected to the protection main line at the incoming end of the residual current circuit breaker. In case of single-phase lighting circuit, three-phase four wire distribution line and other lines or equipment using working zero line, the zero line must pass through current transformer.
3. In the system where the neutral point of the transformer is directly grounded, once the leakage circuit breaker is installed, the working zero line can only be used as the working zero line after passing through the current transformer, and can not be repeatedly grounded or connected with the working zero line of other lines. The electrical equipment can only be connected to the load side of the leakage circuit breaker, and one end is not allowed to be connected to the load side and the other end to the power supply side.