Vacuum Circuit Breaker

A vcb circuit breaker is a kind of circuit breaker where the arc quenching takes place in a vacuum medium. The operation of switching on and closing of current carrying contacts and interrelated arc interruption takes place in a vacuum chamber in the vacuum type circuit breaker. The vcb breaker has the advantages of small size, light weight and frequent operation.

Good price vacuum circuit breaker for sale online in ATO, it is suitable for indoor use. Various vcb breakers with 11kV, 12kV, 15kV, 25kV, 33kV, 35kV, 40kV rated voltage are provided. Rate current of vcb vacuum circuit breaker is 630A, 1250A, 2000A, 2500A, 3150A. Acting to protect and control line is the function of vcb. Vacuum circuit breaker uses widely, it can be a flexible unit to protect line equipment with short-circuit situation or frequent operations. Indoor vacuum circuit breaker can often be seen in transformer substations and industrial and mining enterprises.

Vacuum Contactor vs. Vacuum Circuit Breaker

Vacuum contactor is a device that can withstand multiple operations. It can cut off the load current at the same time, but can not break the short-circuit current. The vacuum contactor has two contacts, normally open and normally closed, and does not have the function of short-circuit current protection. When a given signal is received, it can perform separation and hold actions. It is recommended to use it together with the high-voltage vacuum circuit breaker in the high-voltage environment, which is more safe and reliable.

Vacuum circuit breaker is named because its arc extinguishing medium and the insulation medium of contact clearance after arc extinguishing are high vacuum.It is especially suitable for places requiring no oil, less maintenance and frequent operation. Circuit breakers can be configured in central cabinets, double cabinets and fixed cabinets for control and protection of high voltage electrical equipment. 11kV vacuum circuit breaker can play the role of overload protection, short circuit protection, control protection.

What Problems Can Occur with the Vacuum Circuit Breaker?

• The vacuum circuit breaker refuses to close or open. After the circuit breaker gets the closing (opening) command, the closing (opening) electromagnet acts, the iron core push rod pushes the closing (opening) button open, the closing (opening) spring releases energy and drives the circuit breaker to close (open), but the circuit breaker interrupter cannot close (open).
• Wrong opening of vacuum type circuit breaker. The performance is that the VCB circuit breaker operates normally and trips under unknown reasons.
• The DC resistance of VCB breaker increases. The contact resistance of the contact in the interrupter increases after the indoor VCB runs for a certain period of time.
• Vacuum circuit breaker interrupter cannot be disconnected. The performance is that the circuit breaker cannot be opened or partially opened after opening operation.
• The closing bounce time of indoor circuit breaker increases. Increase the initial pressure of the contact spring appropriately or replace the contact spring. If the clearance between crank arm and axle pin exceeds 0.3mm, the crank arm and axle pin can be replaced.

VCB Breaker Working Principle:

Vacuum circuit breaker structure is mainly divided into three parts: fixed contact, moving contact and arc shield placed in the arc breaking chamber.

The fixed and moving contacts of the 11kV vacuum circuit breaker are placed inside the arc shield. The vacuum interrupter is kept at around 10-6 Torr when it is closed. The moving contacts of the circuit breaker are move through a distance of 5 to 10 mm depending upon the operating voltage.

Metal bellows made of stainless steel are used to move the moving contacts. The design of the metal bellows is very important because the life of the indoor vacuum circuit breaker depends on the repeated operation capability of the element.

When the fault occurs in the system, the contacts of the indoor VCB circuit breaker are moved apart and hence the arc is developed between them. When the current carrying contacts are pulled apart, the temperature of their connecting parts is very high due to which ionization occurs. Due to the ionization, the contact space is filled with vapour of positive ions which is discharged from the contact material. The density of vapour depends on the current in the arcing. Due to the decreasing mode of the current wave, the rate at which they release vapor decreases, and after the current is zero, the medium regains its dielectric strength, provided that the vapor density around the point of contact decreases. Hence, the arc does not restrike again because the metal vapour is quickly removed from the contact zone.