Eaton Power Circuit Breaker MDS-612

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.

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: Breaker accessory voltages can vary within the same breaker. Be sure to review the accessory voltage rating before energizing as damage may occur.

This test procedure assumes that the breaker is equipped with optional shunt trip (ST), undervoltage release (UVR), and/or spring release (SR) accessories (Figure 94). If one accessory is missing, substitute the manual button or manual charge handle to replace the accessory’s function. If equipped with a motor operator, the voltage is listed on the breaker nameplate.

Enter the voltage rating of the breaker

Charge the breaker mechanism springs using the motor operator

If equipped with a UVR, energize the UVR with the rated voltage

Close the breaker by applying rated voltage to the spring release accessory and verify closing by noting the state of the indicating flag

Charge the breaker mechanism springs using the motor operator

If using the motor operator, after charging, remove power to the motor operator to prevent automatic recharging

Open the breaker by applying rated voltage to the shunt trip accessory

Charge the breaker mechanism springs either using the charging handle or the motor operator

Press the ON pushbutton to close the breaker manually and verify closing by noting the state of the indicating flag

Charge the breaker mechanism springs either using the charging handle or the motor operator. If using the motor operator, disconnect power to it to prevent automatic recharging

Press the OFF pushbutton to manually open the breaker

Press the ON pushbutton to manually close the breaker. Is the breaker closed?

Press the OFF pushbutton to manually open the breaker. Is the breaker open?

Note: Repeat this entire described test procedure three times

Sign off on the manual operation functional testing

Device (Fixed): Position of Poles

Device (Fixed): Mechanism Discharged

Device (Fixed): Device Position in Cassette

Device (Drawout): Position of Poles

Device (Drawout): Mechanism Discharged

Device (Drawout): Device Position in Cassette

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