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Page 159

| set to reclose the first time immediately after opening, then wait for one or two seconds before reclosing again, then perhaps five seconds before a third, and ten seconds before a final attempt to reclose. This pattern takes care of the so-called transient or temporary faults or overloads that may cause the breakers to trip. If the abnormal condition is removed or disappears after tripping, the circuit may be re-energized without a long interruption of service. This operation is similar to that of the circuit recloser described in Chap. 8, except that the controls are not self-contained as they are in the recloser. |

| Storage Battery Supply. |

| To insure the continuity and reliability of the control circuits and other devices associated with the operation of circuit breakers, the electric supply is obtained from storage batteries floating on a commercial or distribution supply line; that is, the batteries are permanently connected through suitable transformers, rectifiers, and control devices to the normal electric supply line and are thus kept fully charged at all times. Storage batteries will be discussed at greater length in Chap. 15. |

| Methods of Operation.. |

| Almost all circuit breakers are opened by means of a spring. The spring is compressed during the closing operation and maintained in that position by some form of latching device. When the breaker is called upon to open, the actuating controls trip the latch, thereby permitting the spring to decompress, opening the breaker contacts very rapidly and positively. |

| Circuit breakers may be installed and operated in several different ways: (1) Mounted on a switchboard and direct-operated manually; (2) remote mechanism manually operated; (3) electrically operated; or, (4) pneumatically operated. |

| Switchboard Mounting |

| Circuit breakers of small current-carrying and interrupting capacity for voltages to about 5,000 V may be mounted on a panel and operated directly by a lever; if mounted on the back side of the panel (for greater protection of the operator), the lever can extend through the panel (Fig. 9-2). |

| Remote Mechanisms |

| Circuit breakers arranged for manual operation may also be mounted at some distance from the operating point and actuated by means of linkages or bell-crank mechanisms (Fig. 9-3). This method of operation is subject to |

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