VCB CIRCUIT BREAKER PDF
Tank Type Vacuum Circuit Breaker (SF6 Gas Insulation). We commercialized of the world's first kV rated models. VCB has an excellent anti-seismic. Thus, this is all about Vacuum Circuit Breaker (VCB) working and applications. We hope that you have got a better understanding of this. Toshiba Infrastructure Systems & Solutions Corporation - Switchgear.
|Published:||22 July 2015|
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Vacuum circuit breakers: Multi VCB series
The dielectric strength of vacuum is eight times greater than that of air and four times greater than that of SF6 gas. This high dielectric strength makes it possible to quench a vacuum arc vcb circuit breaker very vcb circuit breaker contact gap.
For short contact gap, low contact mass and no compression of the medium the drive energy required in vacuum circuit breaker is minimum. When two face to face contact areas are just being separated to each other, they do not be separated instantly, the contact area on the contact face is being reduced and ultimately comes to a point and then they are finally de-touched.
Although this happens in a fraction of microsecond, it is a fact. At this instant of de-touching of contacts in a vacuum, the current through the contacts concentrated on that last contact point on the contact surface and makes a hot spot.
As it is a vacuum, the metal on the contact surface is easily vaporized due to that hotspot and create a conducting media for arc path. The air circuit breaker, operated within the voltage level 1 KV, does not require any arc control device. Mainly for heavy fault current on low voltages low voltage level above 1 Vcb circuit breaker ABCs with appropriate arc control device, are good choice.
These breakers normally have two pairs of contacts. The main pair of contacts carries the vcb circuit breaker at normal load and these contacts are made of copper. The additional pair is the arcing contact and is made of carbon. When circuit breaker is being opened, the main contacts open first and during opening of main contacts the arcing contacts are still in touch with each vcb circuit breaker.
As vcb circuit breaker current gets, a parallel low resistive path through the arcing contact during opening of main contacts, there will not be any arcing in the main contact.
The arcing is only initiated when finally the arcing contacts are separated.
Vacuum Circuit Breaker or VCB and Vacuum Interrupter
The vcb circuit breaker of the arc contacts is fitted with an arc runner which helps, the arc discharge to move upward due to both thermal and electromagnetic effects as shown in the figure. As the arc is driven upward it enters in the arc chute, consisting of splitters.
The arc in chute will become colder, lengthen and split hence arc voltage becomes much larger than system voltage at the time of operation of air circuit breaker, and therefore the arc is quenched finally during the current zero.
Although these types vcb circuit breaker circuit breakers have become obsolete for medium voltage application, but they are still preferable choice for high current rating in low voltage application. Air Vcb circuit breaker Circuit Breaker These types of air circuit breaker were used for the system voltage of KV, KV and even more, especially where faster breaker operation was required.
Air blast circuit breaker has some specific advantages over oil circuit breaker which are listed as follows, There is no chance of fire hazard caused by oil.
The breaking speed of circuit breaker is much higher during operation of air blast circuit breaker.
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Arc quenching is much faster during operation of air blast circuit breaker. The duration of arc is same for vcb circuit breaker values of small as well as high currents interruptions. As the duration of arc is smaller, so lesser amount of heat vcb circuit breaker from arc to current carrying contacts hence the service life of the contacts becomes longer.
Vacuum Circuit Breaker (VCB) - Principle, Construction and Working
The stability of the system can be well maintained as it depends on the speed of operation of circuit breaker. Requires much less maintenance compared to oil circuit breaker.
There are also some disadvantages of air blast circuit breakers- In order to have frequent vcb circuit breaker, it is vcb circuit breaker to have sufficiently high capacity air compressor.
Frequent maintenance of compressor, associated air pipes and automatic control equipments is also required. Due to high speed current interruption there is always a vcb circuit breaker of high rate of rise of re-striking voltage and current chopping.