Eaton Power Circuit Breaker MDN-C08

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.

Circuit breaker's arc chutes and arc chambers free of damage or dirt

No significant erosion of the V-shaped plated inside the arc chute

Arc chute screws and all arc chutes removed from the arc chamber

Each arc chute turned upside down and visually inspected

No erosion and sooty discoloration on the splitter plates and insulating jacket

Arc chutes replaced if severe signs of erosion or discoloration are found

Note: Because the arc chutes are removed, this is an ideal time to inspect the primary contacts for wear (See Primary Contact Inspection procedure on page 59).

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.

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 and verified closing by noting the state of the indicating flag

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

Checked the state of the pop-out trip indicator and reset it if it was 'out'

Pressed the ON pushbutton to manually close the breaker and reset the indicator if it was 'out'

Used the Functional Test Kit to trip the breaker by setting its SELECT TEST switch to INST, then pressing its PUSH TO TEST button

Verified that the trip indicator pop-out button is 'out' and then reset it by pressing the pop-out button

Reset the trip unit by the Reset/Battery Test pushbutton on the front of the trip unit

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.

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

2. 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.

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

a. 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.

Device (Fixed): Position of Poles

Device (Fixed): Mechanism Discharged

Device (Drawout): Position of Poles

Device (Drawout): Mechanism Discharged

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

Torque values of the operating mechanism and motor mounting hardware