Therefore while designing the circuit breaker provision of mechanical strength to withstand such sudden release of large quantities of energy must be made.
Arc extinction in circuit breaker.
As the separation between the contacts of breaker increases the arcing resistance also increases.
Method of arc extinction.
The air blast needs an additional compressed air system which supplies air to the air receiver.
This arc is dangerous on account of the energy generated in it in the form of heat which may result in explosive force.
In circuit breaker with plain break arc in oil arc in chutes or narrow slots nearly all the heat loss due to conduction.
Arc extinction when the current carrying contacts of the circuit breaker are moved apart an arc is formed which insist for a short period after the separation of contacts.
Principle of arc extinction.
The main designing criteria of a circuit breaker is to provide appropriate technology of arc quenching in circuit breaker to fulfill quick and safe current interruption.
There are two methods of extinguishing the arc in circuit breaker.
In air blast circuit breaker or in breaker where a gas flow is present between the electrical contacts the heat loss of arc plasma occurs due to convection process.
When opening air is required compressed air is admitted to the arc extinction chamber.
Hence the current is.
It pushes away the moving contacts.
Cross section of the arc.
In high resistance method the arc resistance is made to increase gradually with the time so that the current force in between the two contacts is insufficient to maintain the arc.
In this method the arc resistance is increases gradually so that current is reduced to such a value that heat is insufficient to maintain the arc.
The arcing resistance increases with decrease in the cross sectional area of the arc.
Methods of arc extinction in circuit breaker.
The arc resistance increases as the length of arc increases i e.
These are high resistance methods and low resistance or zero resistance method.
Principle of arc extinction in circuit breaker.
Principles and methods of arc extinction are discussed here.
There are two methods of extinguishing the arc in circuit breakers.
Heat loss from an arc in circuit breaker is takes place through conduction convection as well as radiation.