Trip Unit Replacement

Record all trip unit switch and advanced protection settings for later use.

Disconnect circuit breaker as directed in the circuit breaker instruction bulletin shipped with the circuit breaker. The circuit breaker must be completely isolated. (For a drawout circuit breaker, place circuit breaker in the disconnected position. For a fixed-mounted circuit breaker, all voltage sources, including auxiliary power, must be disconnected.)

Remove circuit breaker accessory cover as directed in the Install Accessories section of the circuit breaker instruction bulletin shipped with the circuit breaker.

A small Phillips screwdriver is needed to remove the adjustable rating plug.

• Open switch cover (A).

• Unscrew adjustable rating plug mounting screw (B).

• Remove adjustable rating plug (C). Save for installation in replacement trip unit.

Remove Adjustable Rating Plug

1. Remove connector block (A) from top of trip unit, if present.

2. Loosen two trip unit screws (B).

3. Slide out trip unit (C).

Remove Existing Trip Unit

Install Battery

Trip Indicator Lights

If a new trip unit is being installed, install the trip unit battery.

Install battery holder with battery (A) in trip unit, observing the correct polarity as indicated on the battery compartment.

Press test/reset button (A). All four indicator lights (B) should light. If they do not light, check polarity of battery and retest. If indicator lights still do not light up when test/reset button is pressed, stop installation and contact the local sales office for factory authorized service

1. Inspect trip unit connector pins and surfaces. If there is any damage, misaligned pins, or contamination, stop installation and contact the local sales office for factory authorized service.

2. Inspect trip unit mounting base on the circuit breaker. Clear any debris from area and check that all accessory wiring is properly routed for the trip unit being installed. If there is any damage or contamination, stop installation and contact the local sales office for factory authorized service.

3. For MasterPacT NW circuit breaker only: Manually depress trip unit interlock (A) and hold it in place during steps 4–6 below.

4. Align guide rail (B) on bottom of trip unit with guide rail slot (C) on trip unit mounting base in circuit breaker and gently slide the trip unit in until it stops.

   NOTE: The MasterPacT NT and NW trip unit mounting bases are shock mounted and therefore can flex slightly.

   Install Trip Unit

   

   CAUTION
   Hazard of equipment damage Check installation of trip unit to assure proper connections and seating. Failure to follow these instructions can result in injury or equipment damage.

5. Align the trip unit so top mounting screw (A) aligns with the top threaded insert and start the screw by turning the screw two full rotations.

6. Use a torque-controlled screwdriver to drive the bottom screw (B) to 7 in-lbs. (0.8 N•m) ± 10%. The back of the trip unit must be flush with the trip unit mounting base.

7. Use a torque-controlled screwdriver to drive the top screw to 7 in-lbs. (0.8 N•m) ± 10%. Mounting tab must be flush with the mounting standoff and sensor plug.

   NOTE: The face of the closed switch cover must be flush with adjoining mounting base surfaces. If these surfaces are not flush, stop installation and contact the local sales office for factory authorized service.
   NOTE: If you are upgrading from a MicroLogic 2.0, 3.0 or 5.0 trip unit, the connector block must be ordered separately (Part Number S33101). See instructions shipped with the connector block for installation into circuit breaker.

8. Install connector block (C) into top of trip unit.

   Secure Trip Unit

   

9. Install adjustable rating plug into the trip unit.

   a. Open switch cover (A) on new trip unit.

   b. Inspect mounting area for debris and contamination.

   c. Gently push adjustable rating plug (B) into new trip unit.

   d. Tighten adjustable rating plug mounting screw (C). The plug will be drawn into position flush with front face as screw is tightened.

10. Set trip unit switches and advanced protection settings to values recorded above or per coordination study results.

11. Close switch cover (A).

    Install Adjustable Rating Plug

    

Field installation of a trip unit requires secondary injection testing with an appropriate test kit. This will ensure that the newly-installed trip unit is functioning properly. The test will require opening and closing the circuit breaker. Follow the procedures outlined in the instruction bulletins shipped with the circuit breaker and the test kit.

1. Make sure the circuit breaker is isolated from all upstream and downstream devices.

2. Perform secondary injection testing as outlined in the instruction bulletin shipped with the test kit. Verify that all applicable trip unit functions are operating properly.

3. If any test fails, do not put the circuit breaker into service and contact the local sales office for factory authorization service.

Primary injection testing is recommended to ensure that all trip system connections have been correctly made. Perform primary injection testing per the instructions in the Field Testing and Maintenance Guide, bulletin 48049-900-xx, where xx is 02 or higher.

1. Installed accessories – Validate the proper operation of all installed accessories. See the corresponding accessory instruction bulletins for operational testing procedures.

2. Programmable contact module – If circuit breaker has an M2C or M6C programmable contact module installed, validate its proper operation. See the corresponding accessory instruction bulletins for operational testing procedures.

3. Zone selective interlocking – If the circuit breaker is part of a ZSI system, follow the zone selective interlocking test procedures as outlined in the appropriate test kit instruction bulletin.

4. Communications – If communication modules exist, confirm circuit breaker has re-established communications with the supervisor.