Circuit breaker is to control the electrical circuit of the switch, if the air for the arc medium called air circuit breaker (switch), if the SF6 gas for the arc medium called sulfur hexafluoride circuit breaker (switch). The circuit breaker is generally rated at the rated current (load) and is used as the main switch for the electrical circuit. In fact, the circuit breaker is a switch, it and other ordinary switch of the main differences in: 1. Applicable voltage level is high; 2. Arc medium and the way, a vacuum, less oil, oil and sulfur hexafluoride and so on; 3. Arc-quenching ability, the effect is good.
The main role of the circuit breaker: 1. Under normal circumstances connected to and disconnect the high voltage circuit in the no-load and load current; 2. In the event of a system failure and protection devices and automatic devices to match, quickly cut off the fault current to prevent accidents Expand, so as to ensure the safe operation of the system.
In general, the circuit breaker itself does not have lubrication problems, the need for lubrication is often its operating mechanism. The role of thermal relay is the motor overload automatically cut off the power supply, thermal relay structure is two pieces of expansion coefficient of different metal sheet composition, the current is too large when the expansion coefficient of the first expansion, play a role in cutting off the power. Thermal relay after manual reset and automatic reset. Fuse Function: When the circuit fails or abnormal, accompanied by rising current, and the rising current may damage some important devices in the circuit or expensive devices, it is possible to burn the circuit or even cause a fire. If the circuit is correctly placed in the fuse, then the fuse will rise in the current to a certain height and a certain time, their own fuse cut off the current, so as to protect the safe operation of the circuit. If the circuit breaker is installed in the circuit breaker, the thermal relay needs to be used in conjunction with the AC contactor. If the contact on the thermal relay is broken, the fuse is usually used for the control circuit.