Eaton Power Circuit Breaker MDS-808

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 from damage or dirt

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).

Device (Fixed): Position of Poles

Device (Fixed): Device Position in Cassette

Device (Drawout): Position of Poles

Device (Drawout): Device Position in Cassette

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

Warning: This procedure requires trained personnel with PPE!

Charged the breaker mechanism springs

Charged the breaker mechanism springs again

Checked the state of the pop-out trip indicator

Pressed the ON pushbutton to manually close the breaker

Used the Functional Test Kit to trip the breaker

Repeat this entire described test procedure three times

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 of the motor operator

Did the breaker mechanism springs charge using the motor operator?

Did the breaker close by applying rated voltage to the spring release accessory?

Did the breaker mechanism springs charge using the motor operator again?

Did the breaker open by applying rated voltage to the shunt trip accessory?

Note: If UVR is not installed, proceed to step 7.

With UVR energized, did the breaker close using the spring release accessory?