Section 2—Visual Inspection and Preventive Maintenance
Molded case circuit breakers normally require very little maintenance. The Company recommends that inspection procedures be performed on a regular basis. Inspection frequency depends on operating and environmental conditions associated with the application.
Visual inspections during operation can be performed any time electrical workers or maintenance personnel are in the vicinity of the electrical equipment.
Maintenance inspections can be done during normal maintenance intervals. It is recommended that the circuit breaker mechanism be exercised annually. Inspection and maintenance may be required more frequently if adverse operating or environmental conditions exist.
Molded Case of Circuit Breakers
The molded case of a Square D molded case circuit breaker should not be opened. Opening the case or disassembling the circuit breaker voids the manufacturer’s warranty and compromises the integrity of the device. Opened or otherwise inoperable circuit breakers should be destroyed or returned to the Company to prevent them from being returned to service. Removal of auxiliary or accessory covers does not constitute opening the molded case.
Procedures
Visual Inspections During Operation
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Hazard of electric shock, explosion, or arc flash
Failure to follow these instructions will result in death or serious injury.
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While circuit breaker is energized:
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Verify circuit breaker application and rating.
Make sure that the circuit breaker is properly applied within labeled voltage, ampere rating, maximum current interrupting ratings and to Company recommendations. Compare the circuit breaker faceplate data to the installation drawings. Verify trip unit settings on MicroLogic electronic-trip circuit breakers with the coordination study. After completing inspection and maintenance procedures, insure that all trip unit settings for all functions are set according to the coordination study.
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Check for overheating while equipment is energized.
While the circuit breaker is normally operating, under load and at operating temperature, check the exposed, accessible, insulated face of the circuit breaker and adjacent dead front surfaces of the enclosure for overheating. To do this, use an infrared temperature probe to check the temperature. If the temperature exceeds 60°C, the cause should be investigated.
Allow initially energized circuit breaker at least three hours to reach operating temperature. Compare the surface temperature of individual circuit breakers with the surface temperature of other circuit breakers in the installation. Circuit breaker surface temperatures vary according to loading, position in the panelboard and ambient temperature. If the surface temperature of a circuit breaker is considerably higher than adjacent circuit breakers, the cause should be investigated.
Thermographic inspection methods may also be used to evaluate overheating with equipment energized (see Thermographic Inspection).
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Check for cracks in the molded case.
Any circuit breaker with a cracked molded case should be replaced because its ability to withstand short-circuit interruption stresses is reduced.
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Inspect the enclosure.
The enclosure should be clean and dry. All covers and trip pieces should be in place.
Maintenance Inspections
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Hazard of Electric shock, explosion, or arc Flash
Failure to follow these instructions will result in death or serious injury.
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While circuit breaker is de-energized:
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Check for overheating while the equipment is de-energized.
Visually inspect electrical components for discoloration. This may indicate overheating. If there is no evidence of overheating or loose connections, do not disturb or re-torque connections.
Copper Connections:
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If evidence of overheating is found on terminals, connectors, conductors or conductor insulation, clean and dress all affected connections and bus bars to NEMA Standards Publication AB4.
Aluminum Connections:
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Overheated aluminum connectors must be replaced and damaged portions of the conductor removed. If the conductor is not long enough to properly terminate the circuit breaker when the damaged portion is removed, make an appropriate splice using a new length of rated conductor.
I-Line™ Panelboard Connections:
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If the I-Line panelboard jaw connections are pitted, discolored or deformed, the circuit breaker must be replaced. I-Line jaws are gauged and tested during the manufacturing process. They are not field replaceable. Do not bend or adjust them.
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If electrical joint compound is removed from I-Line connections, it must be reapplied before reinstallation of the circuit breaker(s). This compound is necessary to ensure the integrity of the connection. ILine panelboard connections require Square D PJC-7201 joint compound.
NOTICE Hazard of Equipment DamageDrawout connection lubrication must be reapplied each time the circuit breaker is removed from the cradle.Failure to follow these instructions can result in equipment damage.Drawout Connections:
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If circuit breaker drawout connections are discolored or deformed, the circuit breaker must be replaced.
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Drawout connections must have lubrication applied each time the circuit breaker is removed from the cradle. This compound is necessary to ensure the integrity of the connection.
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Drawout connections for SE circuit breakers require Square D PJC8311 joint compound.
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Drawout connections for PowerPacT circuit breakers require grease kit S48899 to lubricate clusters and stabs.
After cleaning and/or replacing damaged parts, torque all connections to values specified by Square D. Refer to circuit breaker instruction bulletins for additional information regarding torque values. Bulletins are shipped with the circuit breakers and are available from the Square D internet technical library.
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Exercise circuit breaker mechanism:
Toggle the circuit breaker handle on and off several times to ensure that mechanical linkages are free. Trip the circuit breaker with the push-to-trip button. Reset and turn the circuit breaker back on. Repeat to ensure operability. If the circuit breaker does not trip, or if it does not reset after tripping, it must be replaced.
NOTE: The Visi-Trip LED handle aids in quickly locating a circuit breaker that requires attention. Inspect the handle position for circuit breaker trip indication.NOTE: When performing annual maintenance in accordance with MCCB Field Testing and Maintenance Guide (0600IB1201), operate the push to trip button (if equipped) to verify the Visi-Trip functionality. Cycle the circuit breaker from tripped to OFF, and then from OFF to ON and take note of the battery health.Light Pattern Indicator Fast flash for two seconds. Battery low (20% remaining).* Long duration slow flash (continuous flash for six hours). The circuit breaker requires inspection. -
Clean the circuit breaker. Remove any buildup of dust, dirt, grease or moisture from circuit breaker surfaces with a lint-free dry cloth or vacuum cleaner. Do not use compressed air. Use caution when using detergent-based cleaners or solvents: these may deteriorate faceplate, labels, and insulation materials. Clean contact surfaces of circuit breaker terminals and terminal pads or bus bars with a nonabrasive cleaner. Abrasive cleaners will remove plating, resulting in joint deterioration.
If electrical joint compound is removed from I-Line or SE drawout connections, Square D PJC-7201 or PJC-8311 joint compound, respectively, must be reapplied before reinstalling the circuit breakers. This compound is necessary to ensure the integrity of the connection.
Thermographic Inspection
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Hazard of Electric Shock, Explosion, or Arc Flash
Only qualified electrical workers with training and experience
on low-voltage circuits should perform thermographic inspections.
These workers must understand the hazards involved in working with
or near low-voltage equipment. Perform such work only after reading
this complete set of instructions.
Failure to follow these instructions will result in death or serious injury.
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Infrared thermographic inspection techniques may be useful in evaluating the operating condition of circuit breakers and terminations. Comparison to stored infrared thermographic images may be useful for the preventive maintenance of circuit breakers and end-use equipment. The actual amount of heat emitted is a function of both load current and ambient conditions. Interpretation of infrared survey requires experience and training in this type of inspection.
Allow initially energized circuit breakers at least three hours to reach operating temperature. Compare the thermographic images of individual circuit breakers to previously stored images of the same circuit breakers.
Additional Information
For more information concerning Square D circuit breakers, refer to the appropriate instruction manual. These manuals contain installation instructions, mounting information, safety features, wiring diagrams, and troubleshooting charts for specific circuit breakers.