The role of the circuit breaker

Circuit breaker is the electric circuits of the control points in the air if arcing medium for the said air circuit breaker (switch), if the SF6 gas as arcing medium according to sulfur hexafluoride circuit breaker switch. Circuit breaker with rated current (load), commonly used as the electric circuits of the main switch. Circuit breaker is actually a kind of switch, it and other common switch differences mainly in: 1. Apply high voltage grade; 2. The arcing medium and way, vacuum, less oil, more oil and sulfur hexafluoride, etc. 3. The arcing ability is strong, the effect is good.
The main purpose of the circuit breaker: 1. Under normal circumstances on and off the no-load and load current in high voltage circuit; 2. A failure occurs in the system can be made to match the protection device and automatic device, cut off the fault current quickly, prevent accident expanding, thus ensuring the safe operation of the system.
In general the circuit breaker itself does not exist lubrication problems, need lubrication is often its operating mechanism. The function of thermal relay is automatically cut off power supply when the motor overload, the structure of the thermal relay is made by the two different pieces of metal expansion coefficient, the first expansion of the large expansion coefficient when current is too large, have the effect of cut off power supply. After thermal relay operation manual reset and automatic reset. Fuse function: when circuit failure or abnormal, with the current rising, and possibly the rise in current damage or expensive some important components in the circuit, and may even cause fire burned circuit. If correctly placed the fuse in the circuit, so, fuse in the abnormal current increases to a certain height and due time, fusing itself to cut off the current, so as to protect the safe operation of the circuit. If installed in the circuit breaker can not fuse, thermal relay needs to be used with ac contactor, because of overload on the thermal relay when off contact to cut off the control circuit, the current fuse more commonly used in the control loop.