CIRCUIT BREAKER\
A circuit breaker can make or breaker a circuit either manually or automatically under no load , full load or short circuit conditions.
ARC FORMATION
Under faulty conditions heavy current flows through the contacts of the circuit breaker before they are opened. as soon as the contacts start separating, the area of contact decreases which will increase the current density and consequently rise in the temperature.The medium between the contacts of circuit breakers may be air or oil. The heat which is produced in the medium is sufficient enough to ionise air or oil which will act as conductor . Thus an arc is struck between the contacts . The potential difference between the contacts is sufficient to maintain the arc.
so long as the arc is remaining between the contacts the circuit is said to be uninterrupted
The current flowing between the contacts depends on the arc resistance. with increase in arc resistance the current flowing will be smaller. The arc resistance depends on following factors.
DEGREE OF IONISATION:-
If there are less number of ionised particles between the contacts then the arc resistance increases.
LENGTH I OF ARC:-
the arc resistance is a function of length of arc which is nothing but separation between the contacts. more the length more is the arc resistance
CROSS SECTION OF ARC
If the area of cross sectional of the arc is less then arc resistance is large.
CONTINUE....... IN NEXT SLIDE
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