Universal circuit breaker (frame circuit breaker) is a mechanical switchgear that can connect, carry and disconnect current under normal circuit conditions, as well as connect, carry and disconnect current for a certain period of time under specified abnormal circuit conditions (such as short circuit, overload, etc.). It usually has a high rated current and breaking capacity, and is an important protection and control device in the power system.
It mainly consists of contact system, arc extinguishing system, operating mechanism, release device, and housing. Its working principle is based on the combination of electromagnetic induction and mechanical action. Under normal working conditions, current flows through the contact system and the operating mechanism keeps the contacts closed. When faults such as overload, short circuit, or undervoltage occur in the circuit, the corresponding release (such as thermal release, electromagnetic release, undervoltage release) will activate. For example, a thermal release device will deform the bimetallic strip due to the thermal effect of the current when overloaded, pushing the operating mechanism to disconnect the contacts; The electromagnetic release quickly operates under the strong electromagnetic force generated by the short-circuit current, achieving rapid disconnection.
Ambient temperature:-5℃~+40℃，and average temperature in24 hours below+35℃(except for special orders).
Elevation of installation site:<=2000m.
Relative humidity:not exceeding 50%at the maximum ambient temperature,higher humidity would be permitted,but the lowest average temperature in a month not exceeding +25C during the most moist month,and the maximum monthly average relative humidity not exceeding 90%in that month,and giving consideration the dews on the goods surface,which would appear due to temperature change.
Pollution protection:3 grade.
Protection grade:IP30.
Installing categories:IV for breaker main circuits,coils of under voltage release and primary circuit of transformers;lll for other auxiliary circuits and control circuit.
The breakers should be installed according to stipulations in operation manual.For breakers in common use,the vertical gradient isn’t more than 5C,for that used on mine,the vertical gradient isn’t more than15C.
The fixed circuit breaker is mainly composed of contact system,insulating base,intelligent controller,manual operating mechanism, electric operating mechanism and mounting plate.The drawer type circuit breaker is mainly composed of contact system,insulating base,intelligent controller,manual operating mechanism,electric operating mechanism and drawer base. The circuit breaker is a three-dimensional arrangement with the characteristics of compact structure and small volume.The contact system is enclosed in the insulating base plate,and each phase of the contact is also separated by the insulating plate to form a small room.The intelligent controller,manual operating mechanism and electric operating mechanism are arranged in front of each other to form their own independent units.If one of the units is broken,the whole unit can be removed and replaced with a new one. The drawer type circuit breaker consists of a plug-in circuit breaker and a drawer base.The guide rail in the drawer base can be pulled in and out,the inserted circuit breaker is located on the guide rail to enter and exit the drawer,and the main circuit is connected through the insertion and connection of the bus on the inserted circuit breaker and the bridge contact on the drawer base The drawer type circuit breaker has three working positions:”connection”position,”test”position and “separation”position.The position change is realized by screwing in or out the handle,and the indication of the three positions is displayed by the pointer on the crossbeam of the drawer base.
