Ques. What is the object of the carbon contacts?
Ans. First to protect the intermediate contacts by providing a path for the current after the intermediate contacts separate, and 2, to "slow down" the current by means of the considerable resistance of the carbon, thus reducing to a minimum the arc which is formed when the carbon contacts separate.
Ques. How is the automatic operation of a circuit breaker usually accomplished?
Ans. Usually through the medium of a solenoid, or electromagnet energized by current from the circuit controlled by the breaker.
Fig. 2,249.—Mechanically connected insulated latches used on Condit circuit breakers to produce inter-locking tripping.
The essential features of construction and operation of a circuit breaker is shown in the elementary diagrams, figs. 2,250 to 2,253. In construction as shown in fig. 2,250 it consists essentially of three sets of contacts, a swinging contact arm which is set in the closed position by the handle operating through the toggle joint, the movement of which is limited in the closing direction by the stop. The latter is made adjustable by an eccentric pin or equivalent. Connected to the toggle is the plunger of the solenoid whose winding is energized by current from the circuit which the circuit breaker is to control.
