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Page 174

TABLE 9-1 Troubleshooting Circuit Breakers

Condition

Possible Cause

Suggested Remedy

Overheating

| Contacts out of proper alignment and adjustment |

Line up contacts and adjust properly.

| Contacts dirty or greasy | Remove accumulated dirt.

| Contacts burned and pitted from too frequent operation or many heavy interruptions |

| Dress up contacts and fit properly, or replace with new parts. (High-pressure, butt-type contacts usually do not require dressing; silver-to-silver contacts should be dressed very carefully but only when actually required.) |

| Breaker kept open or closed for too long a period; copper contacts oxidized |

| Operate breaker more frequently to wipe contacts clean; perhaps replace them with silver-to-silver contacts. |

| Overloading (continuous or prolonged current in excess of rating) |

Replace with adequate rating breaker or remove excess load.

| Heat transmitted to breaker from overloaded or inadequate connecting cables or bars |

Increase number or size of bars, or reduce loads.

| Loose connections on terminal connectors |

Tighten connections.

| Location too hot an ambient | Relocate to cooler place, or ventilate and cool.

Failure to trip

| Mechanism binding or sticking: Lack of lubrication |

Lubricate mechanism.

| Out of adjustment | Adjust toggles, stops, springs, links, etc.
| Failure of latching device | Check and adjust wipe, or replace if worn or corroded.

| Auxiliary contacts and interlocks not making proper contact; damaged trip coil |

| Check contacts; clean if dirty or tarnished; adjust if out of adjustment. Replace damaged parts or trip coil. |

| Damaged or dirty contacts on tripping device |

Dress or replace damaged contacts, or clean dirty contacts.

| Faulty connections in trip circuit | Repair loose or broken wires. Tighten binding screws.
| Blown fuse in control circuit | Replace blown fuse. Check for grounds or short circuit.

| (table continued on next page) |

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