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Page 168

| time and tripping arrangements should be checked as they were for electrical operation. |

| Accessories |

| Undervoltage devices should be checked to make sure that tripping will be positive if the voltage drops to, or below, a predetermined value. If a time delay is included, the time setting should be checked. Auxiliary switch adjustments and contacts should be checked. Grounding connections on breaker frames should be checked to be sure that they are intact and directly connected to a dependable ground for safety. Mechanical and electrical interlocks should be checked to make sure that they are functioning properly and that all adjustments are correct. Cyclometers, or operation counters, should be checked for proper operation. Heaters, should they exist, should be checked to see whether they are in good operating condition. If thermostat controls are associated with them, the settings and operation of the thermostat should be checked. |

| General |

| Bolts, nuts, pins, cotter pins, pipe plugs, pipe fittings, as well as rods, levers, links, and other items should be in place and tight. Broken, worn, or damaged parts should be replaced. Gaskets and seals should be checked and replaced if worn or leaking. Connections, splices, and terminals should be checked to make sure that they are clean and tight. Painted surfaces of oil tanks, housings, and the like, should be checked, and damaged, scarred, or scratched places touched up to avoid corrosion. |

| Testing.. |

| The frequency of maintenance depends on many factorslocal conditions, importance of the equipment being protected, and, to a great extent, on the number of operations engaged in by the breaker and the duty imposed on it. In certain cases of severe duty, such as the interruption of a heavy short-circuit current, a special inspection and maintenance may be advisable. On the other hand, if operating conditions leave a breaker inoperative for long periods of time, it may be well to open and close it periodically to make sure that all parts are in proper operating condition. |

| Since circuit breakers are not often called upon to operate under severe conditions for long periods of time, lengthy, expensive maintenance procedures can be reduced substantially by substituting simple, relatively inexpensive tests that can be performed in short order. Such tests can be made |

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