Eaton Power Circuit Breaker MDN-612

Check device (Fixed) conditions

Check device (Drawout) conditions

Verify breaker secondary disconnect pins are fully seated and locked

Ensure all pins are straight without bends, corrosion, or evidence of arcing

Warning: Remove all power to the cassette secondary pins

Inspect the breaker for nicked wires, cracks in plastic parts, and loose screws

Tighten screws or bolts to levels outlined in Table 22

Apply thread-locking compound to loose screws in plastic parts

Replace or repair all nicked wiring according to industry practices

Are the torque values of the operating mechanism and motor mounting hardware within recommended values in Table 18?

Charge the breaker mechanism springs

Press the ON pushbutton to close the breaker manually

Verify closing by noting the state of the indicating flag (Figure 93)

Charge the breaker mechanism springs again

Disconnect power to the motor operator to prevent automatic recharging

Press the OFF pushbutton to manually open the breaker

Press the ON pushbutton to manually close the breaker

Ensure all primary and secondary power is removed for fixed mounted circuit breakers

Verify breaker operation by charging, closing, recharging, and opening the breaker

Mechanical Interlock Verification

Verify breaker does not close with Undervoltage Release not energized

Verify breaker does not close with levering-in screw access door open

Use the mating line of the housing halves as a reference guide for visual inspection

Remove the arc chutes and inspect each primary contact structure for signs of wear and/or damage

Use the contact wear indicator to inspect each contact

Is the back end of any contact below the ledge?

Replace the contact assembly if any contact is below the ledge