Technical data

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Routine Maintenance Guidelines

Recommended Inspection Intervals

MASTERPACT circuit breakers are designed to be maintenance free (see page 64). However, all

equipment with moving parts requires periodic inspection to ensure optimum performance and

reliability. It is recommended that the circuit breakers be routinely inspected six months after

installation, followed by an annual inspection. Intervals can vary depending on particular use and

experience.

Inspection of Circuit Breaker Terminals

n Inspect terminals; if there is discoloration due to overheating, the joint should be disassembled

and the surface cleaned before reinstallation. It is essential that electrical connections are made

carefully in order to prevent overheating.

n Check for terminal tightness.

Inspection of Main Contacts

The arc chutes are easily removed to allow access to the main contacts and to the wear indicator.

The wear indicator consists of a groove located within the contacts support (see page 3). When the

circuit breaker is closed, this groove is entirely covered up by the moving contacts. Over time, the

wear of the contacts will make the groove appear. When the groove is fully visible, replace the

breaker or have an authorized service center change the contacts.

Inspection of Clusters

Totally maintenance free, they have to be replaced only after overheating due to a defective

connection or after a major fault. Inspection is advised when checking the terminal connections.

Cleaning

Remove any dust and dirt that may have accumulated on the circuit breaker surface and terminals.

Mechanical Checks

For long periods circuit breakers may not be required to operate on overload or short-circuit

conditions. Therefore it is essential to operate the circuit breaker periodically to avoid mechanical

gumming.

Appendix

HAZARD OF ELECTRICAL SHOCK, BURN

OR EXPLOSION.

Turn OFF all power supplying the equipment

before installing or removing circuit breaker.

Failure to observe these precautions will

cause death, personal injury or electrical

shock.

DANGER

HAZARD OF EQUIPMENT DAMAGE.

Since circuit breakers contain factory-sealed

and calibrated elements. Do not break seal. In

case of malfunction, repairs must be made at

a Square D factory or by an authorized

company representative.

Failure to observe this precaution can

cause equipment damage.

CAUTION