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Page 157

| 9 Circuit Breakers: Operation and Maintenance |

| Controls.. |

| Although circuit breakers may be opened and closed directly by manual means, more often they are opened and closed by remotely controlled electrical means. |

| Trip-Free Feature |

| The operating mechanisms of most circuit breakers are designed to prevent the breakers from staying closed on a fault or overload condition. This characteristic is referred to as trip-free. If a breaker trips open and the abnormal condition that caused it to do so persists, any attempt to close the breaker will cause it to trip again immediately. The tripping device, as long as it is activated, will prevent the mechanical linkages of the mechanism from engaging to close the breaker. Even if an attempt is made to close the breaker manually, it cannot be kept closed so long as the abnormal condition exists. (Fig. 9-1). |

| Antipump Feature |

| Electrically operated breakers have antipump provisions included in their control circuits. If an attempt is made to reclose a breaker by holding the control handle in the close position while the fault or overload persists, the breaker will attempt to trip and close, trip and close, indefinitely (since the |

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