Eaton Eaton Power Circuit Breaker MDN-512 MDN-512

Warning: This procedure requires trained personnel with PPE!

Charged the breaker mechanism springs using the charging handle or the motor operator

Closed the breaker by applying rated voltage to the spring release accessory

Verified closing by noting the state of the indicating flag

Charged the breaker mechanism springs again using the charging handle or the motor operator

Disconnected power to the motor operator to prevent automatic recharging

Checked the state of the pop-out trip indicator

Reset the pop-out trip indicator if it is 'out'

Pressed the ON pushbutton to manually close the breaker

Pre-Inspection Conditions: Device (Fixed): Position of Poles: Open, Mechanism: Discharged, Device Position in Cassette: -. Device (Drawout): Position of Poles: Open, Mechanism: Discharged, Device Position in Cassette: Removed.

WARNING: REMOVE THE DRAWOUT CIRCUIT BREAKERS FROM THE CASSETTE FOR THE FOLLOWING TESTS. FOR FIXED MOUNTED CIRCUIT BREAKERS, ALL PRIMARY AND SECONDARY POWER IS TO BE REMOVED.

Procedure: Note: The circuit breaker will be required to be charged, closed, and opened during this inspection procedure.

Verify that the breaker is in working order by charging the breaker, closing the breaker, recharging the breaker, and opening the breaker.

Note: The breaker will need to be charged and opened for this inspection procedure.

Verify that the circuit breaker will not close if any of the following mechanical conditions exist:

If the breaker is equipped with an Undervoltage Release that is NOT energized, and the breaker is charged and opened, depress the ON (close) pushbutton The breaker should not close.

For drawout breakers, lift the levering-in screw access door With the door open or not fully closed, depress the ON (close) button The breaker should not close.

Pre-inspection conditions: Device (Fixed): Position of Poles: Open, Mechanism: Discharged, Device Position in Cassette: -. Device (Drawout): Position of Poles: Open, Mechanism: Discharged, Device Position in Cassette: Removed.

Note: Using the mating line of the housing halves as a reference guide will assist in this visual inspection.

Remove the arc chutes, look directly down into the arc chamber (Figure 98), and visually inspect each primary contact structure for signs of wear and/or damage.

Use the contact wear indicator to inspect each contact The contact wear indicator is the relative position of the individual contact fingers to a narrow, side-to-side ledge inside the arc chamber The ledge is actually part of the arc chamber When the circuit breaker is closed and the contacts are in good condition, the narrow ledge is covered by the back end of each of the contact fingers (Figure 99) If the back end of any of the contacts are below the ledge, the contact assembly should be replaced.

Once the inspection is complete, be sure to verify the arc chutes are properly replaced as previously described in the Arc Chute Inspection procedure.

WARNING: ARC CHUTES MUST BE SECURED PROPERLY IN PLACE BEFORE A CIRCUIT BREAKER IS INSTALLED IN A CIRCUIT BREAKER COMPARTMENT. FAILURE TO DO THIS COULD RESULT IN EQUIPMENT DAMAGE, BODILY INJURY, OR EVEN DEATH.

Device (Fixed): Position of Poles

Device (Fixed): Position in Cassette

Device (Drawout): Position of Poles

Device (Drawout): Position in Cassette

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

Device (Fixed): Position of Poles: Open, Mechanism: Discharged, Device Position in Cassette: -.

Device (Drawout): Position of Poles: Open, Mechanism: Discharged, Device Position in Cassette: Removed.

For Magnum Breakers with Vertically Mounted Primary Disconnects:

1. With breaker removed from cell, verify that vertical adapter nuts and bolts are torqued to 37–43 lb-ft.

For All Magnum Breakers Primary Disconnects:

1. Remove the primary disconnect.