Vacuum Circuit Breaker
Sectional view of a Vacuum Circuit Breaker, marketed by M/s Driescher Picnicker Madras is shown is Fig. (6) the most important part is the vacuum interrupter, blown up view of which is given in Fig. (7) When the contacts separate, the current to be interrupted initiates a metal vapor arc discharge and flows through this plasma until the next current zero.
The arc is then extinguished and the conductive metal vapor condenses on the metal surfaces within a matter of microseconds.
As a result, the dielectric strength in the break builds up very rapidly.
The self generated field causes the arc root to travel, thereby preventing local overheating when large currents are being interrupted. Certain minimum current is necessary to maintain the metal vapor arc discharge.
Current of a lesser value is chopped prior to current zero, causing unduly high voltages, as may happen during interruption of no load magnetizing currents of unloaded Transformers.
The rapid build up of the dielectric strength in the break enables the arc to be safely extinguished even if contact separation occurs immediately prior to current zero the maximum arcing time for the last pole to clear is stated to be 15 ms.
Further the arc voltage developed in vacuum interrupter is low (say between 20 to 200 V) due to high conductivity of metal vapor plasma.
For there reasons the arc energy developed in the break is very small. High Switching life is claimed on this account. Performance is claimed to be immune to pollution because of interrupters being hermetically sealed.
The manufacturing range of M/s Driescher Panicker covers Vacuum Circuit Breakers up to rated voltage of 36 kV.
Vacuum Circuit Breakers are specially suited in industrial applications, where the Switching frequency is high combined with high degree of pollution. www.sayedsaad.com
1 - Vacuum Interrupter
3 - Flexible connection .
5 - Operating rod.
7 - Common operating shifts
9 - Locking cam.
11 - Breaking spring.
13 - Main link.
1- cast resin post insulator
2- upper connection
3- upper contact support
4- 5- fastening nuts
6- Rear pull strap
7- Front pull strap
8- vacuum Switching chamber
9- contact Switch with toroidal
contact Lower contact support
Consisting of :-
10.1 transmission lever
10.2 burn-off indicator
10.3 actuation crank
10.4 actuation lever
10.5 telescope rod with contact spring
11 hook stick
Construction of the Switch pole type VA, VXC