Eaton Eaton Power Circuit Breaker MDN-408 MDN-408

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.

2. With breaker removed from cell, verify that the breaker secondary disconnect pins are fully seated and locked into position by lightly pulling on each wire individually.

Note: Do not exceed 1 lb of force or damage to pin or housing may occur.

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

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.

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

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.

Rotate the levering-in screw and verify that the door does not close in intermediate positions The door should only close in the full disconnect, test, and connect positions.

Return the drawout levering-in screw to the disconnected position.

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.

When a circuit breaker experiences a high-level fault or during regularly scheduled maintenance periods, the circuit breaker’s arc chutes and arc chambers should be inspected for any kind of damage or dirt. Be especially alert for signs of significant erosion of the V-shaped plated inside the arc chute.

Arc chutes fit inside the arc chambers and down over the primary contacts. Each arc chute is held in place by either 1 (SB) or 4 (SBSE) top inserted screws.

Remove arc chute screws and all arc chutes from the arc chamber.

Turn each arc chute upside down and visually inspect the inside.

Look for erosion and sooty discoloration on the splitter plates and insulating jacket If arc chutes show severe signs of erosion or discoloration, replace with a new arc chute.

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).

When the inspections are complete, position each arc chute over its respective set of primary contacts, and secure in place with the screw(s) removed earlier Be sure to torque arc chute screws to 35 to 45 in-lb.

Sign off on the arc chute inspection

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

Warning: This procedure requires trained personnel!

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

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 either by using the charging handle or the motor operator. If using the motor operator, disconnect power to it to prevent automatic recharging

Check the state of the pop-out trip indicator (if so equipped). If it is 'out,' then reset it

Press the ON pushbutton to manually close the breaker. If the indicator is 'out,' then reset it

Use the Functional Test Kit to trip the breaker by setting its SELECT TEST switch to INST, then pressing its PUSH TO TEST button. Verify that the trip indicator pop-out button (if so equipped) is 'out' and then reset it by pressing the pop-out button. The trip unit then needs to be reset by the Reset/Battery Test pushbutton on the front of the trip unit

Repeat this entire described test procedure three times. Digitrip 520 trip units require power to the trip units to be reset

Upload a photo of the completed test