Cummins/Onan OTPC Generator Set

Tools: Ohmmeter

1. Remove the connector from J25 on the Digital Module circuit board.
2. Press the switch down and measure the resistance between the switch common (pin 10) and each switch at the solder points on the connector.
3. The resistance of a closed membrane switch should be in the range of 0 to 200 ohms depending on how hard you press.
4. Attach the connector to J25.
5. Close and lock the enclosure door.

Tools: Wiring break-out tool (34 pin) contained in the Cummins PCC Tool Kit, P/N 3824746

1. When a Power Module failure occurs, the most common part to fail is the transformer.
2. Use a 34-pin wiring break-out tool to measure J11 test points.
3. Check the Source 1 and Source 2 transformer inputs and the regulated DC output at J18/J19.
4. Check the CR3, CR4, CR5 output of 20-30 VDC at J11-29.

⚠ The transfer switch presents a shock hazard that can cause severe personal injury or death unless all AC power is removed.

⚠ Ignition of explosive battery gases can cause severe personal injury. Do not smoke or cause any spark, arc, or flame while servicing batteries.

1. Disconnect all sources of AC power; turn the genset operation selector switch to Stop; disconnect the battery charger and the starting battery (negative lead first).
2. Thoroughly dust and vacuum all controls, meters, switching mechanism components, interior buswork, and connecting lugs.
3. Close the cabinet door and wash exterior surfaces with a damp sponge (mild detergent and water); do not allow water to enter the cabinet.
4. Check buswork and supporting hardware for carbon tracking, cracks, corrosion, or deterioration.
5. Check stationary and movable contacts.
6. Check system hardware, control wiring, and power cables for loose connections, wear, or deterioration.
7. Tighten buswork, control wiring, power cables, and system hardware as necessary; retorque all cable lug connections.
8. Service or replace the 3V lithium batteries in the Digital Module and the Network Module; replace every two years.
9. Connect the set starting battery (negative lead last); reconnect normal AC power and verify battery charger operation.
10. Test system operation; close and lock the cabinet door.

1. Set the Test With/Without Load variable to the Without Load value.
2. Press the Test switch. The generator set should start and run.
3. At the end of the test period, press the Test switch again. The generator stops.
4. In anticipation of scheduled exercise, set the With/Without Load variable to the desired value.

⚠ Manual operation of the transfer switch under load presents a shock hazard that can cause severe personal injury or death. Do not attempt to operate switch manually when under load.

⚠ Automatic transfer switch operation results in rapid movement of the manual operator handles. Keep hands clear of handles when switching back to automatic operation.

1. Open the cabinet door of the ATS.
2. Move the Motor Disconnect switch to the Off position.
3. Transfer from Source 1 to Source 2: pull the upper manual operator handle down, then push the lower manual operator handle down.
4. Retransfer from Source 2 to Source 1: pull the lower manual operator handle up, then push the upper manual operator handle up.
5. Move the Motor Disconnect switch to the Auto position.
6. Close the cabinet door.

1. Set the Test With/Without Load variable to the With Load value.
2. Press the Test switch. The generator set should start and assume the load after the transfer time delay.
3. Press the Test switch again to retransfer load back to Source 1 after the retransfer time delay.
4. To bypass the retransfer time delay and cause immediate load retransfer, press the Override switch. The generator stops after the stop time delay.

⚠ AC power within the cabinet presents an electrical shock hazard. Disconnect all sources of AC power from the transfer switch before servicing.

1. Open the cabinet door and remove the four machine screws securing the plastic switch cover.
2. Loosen the two machine screws securing the terminal bracket to the base and move the bracket for access.
3. Remove the control wiring leads from the auxiliary switch terminals.
4. Remove the hex head machine screws securing the auxiliary switch assembly bracket to the base.
5. Disengage the auxiliary switch lever from the transfer switch crossbar and lift out the assembly.
6. Remove the hex head machine screws and nuts securing the auxiliary switches to the bracket; lift out the four switches, insulating barriers, and switch lever.
7. Place the auxiliary switch lever in the bracket (end with the octagonal hole engages the crossbar).
8. Install the auxiliary switches (4) and insulating barriers (5) in the bracket; secure with hex head machine screws (2) and nuts (2); tighten to 10-15 in-lbs (1.1-1.7 Nm).
9. Manually close the contacts coupled to the auxiliary switch lever and check lever alignment when the switch is closed.
10. Secure the bracket to the base with hex head machine screws; tighten to 25-30 in-lbs (2.8-3.4 Nm).
11. Install control wiring leads on the corresponding switch terminals; place the terminal bracket and tighten to 25-30 in-lbs.
12. Secure the plastic switch cover and tighten to 25-30 in-lbs (2.8-3.4 Nm).
13. Reconnect the starting battery and power sources; test the switch for proper operation and close the cabinet.

⚠ AC power within the cabinet presents an electrical shock hazard. Disconnect all sources of AC power from the transfer switch before servicing.

1. Remove the linear actuator as described for 40-125 ampere switches (steps 1-6 of Removing Actuator).
2. Remove the interlock bar from the interlock arms.
3. Disconnect the control wiring leads from the jumper bus bars.
4. Remove the hardware securing the jumper bus bars to the load bus bars and lift off the jumper bus bars.
5. Remove the control wiring leads from the power source terminals and remove the power source supply wires from the lug terminals.
6. Remove the two round head machine screws, lock washers, and flat washers securing the block assembly to the base; remove the assembly.
7. Clean all current-carrying surfaces with a wire brush.
8. Hold the block assembly in position and check alignment of the auxiliary switch lever; it must be aligned vertically when contacts are closed.
9. Secure the block assembly to the base with round head machine screws (2), lock washers (2), and flat washers (2); tighten to 25-30 in-lbs (2.8-3.4 Nm).
10. Install power source supply wires, control wiring to power source terminals, and the jumper bus bars with electrical joint compound; tighten as specified.
11. Apply thread sealant (Loctite 242, P/N 518-0309) to the interlock bar machine screws; install and tighten to 15-20 in-lbs (1.7-2.3 Nm).
12. Attempt to close both sides of the transfer switch; the interlock assembly must hold one side open.
13. Replace the linear actuator per steps 2 through 8 of Replacing Actuator; apply lubricant (P/N 524-0157) to the slot in the handle.
14. Test the switch for proper operation and close the cabinet.

⚠ AC power within the cabinet and the inside of the cabinet door presents a shock hazard. Remove power to the door by disconnecting connector J1/P1 before working on the electronic control system.

Tools: InPower service tool

1. Place the motor disconnect switch in the Off position.
2. Disconnect connector P1.
3. Remove the old digital board and install the new one.
4. Connect connector P1.
5. Use InPower to perform an initial calibration on the replacement digital board; select settings and features to match the nameplate values.
6. Write a capture file to the replacement board, or set up individual parameters if no good capture file is available.
7. Remove all power from the digital board, including the batteries, for the changes to take effect.
8. Place the motor disconnect switch back in the On position.

⚠ AC power within the cabinet presents an electrical shock hazard. Disconnect all sources of AC power from the transfer switch before servicing.

1. Disconnect both Source 1 and Source 2 and the genset starting battery (negative lead first).
2. Remove the two self-locking nuts and two machine screws securing the plastic switch cover and lift off the cover.
3. Separate the actuator lead wires from the wiring harness; remove wire ties as required.
4. Pry the capacitor(s) loose; disconnect the red and white leads from the capacitor terminals.
5. Disconnect the black actuator wire from the circuit breaker and the ground wire from the end of the actuator.
6. Remove the hardware securing the actuator to the switch assemblies and lift out the spacers (4) and barriers (2).
7. Disengage the actuator rod from the switch handle and remove the actuator.
8. Remove the rod end assembly from the actuator rod and slide the rod out of the actuator motor.
9. Insert the actuator rod into the replacement motor; install the rod end assembly and tighten capscrew to 70-75 in-lbs (7.9-8.5 Nm).
10. Position the actuator over the switch assemblies with lead wires at the bottom; fit the rod assembly into the handle of the closed switch assembly.
11. Secure the actuator with hex head capscrews (4), lock washers (4), flat washers (4), barriers (2), and spacers (4); tighten to 25-27 in-lbs (2.8-3.0 Nm).
12. Connect the black lead to the circuit breaker and the red and white leads to the capacitor terminals.
13. Connect the ground wire; check operation and rod alignment; secure the plastic cover and tighten to 25-30 in-lbs.
14. Reconnect the starting battery and power sources; test and close the cabinet.

⚠ AC power within the cabinet presents an electrical shock hazard. Disconnect all sources of AC power from the transfer switch before servicing.

1. Disconnect both Source 1 and Source 2 from the transfer switch and the genset starting battery (negative lead first).
2. Open the cabinet door and remove the four machine screws securing the plastic switch cover.
3. Separate the actuator lead wires from the wiring harness; remove wire ties as required.
4. Pry the capacitor(s) loose; disconnect the red and white leads from the capacitor and the black lead from the circuit breaker.
5. Remove the socket head capscrews and lock washers securing the actuator to the block assemblies; note the ground wire on the lower left capscrew.
6. Disengage the actuator rod from the switch handle and remove the actuator from the block assembly.
7. Remove the rod end assembly from the actuator rod and slide the rod out of the actuator.
8. Insert the actuator rod into the replacement actuator motor; install the rod end assembly and tighten the capscrew to 70-75 in-lbs (7.9-8.5 Nm).
9. Position the actuator motor on the block assemblies so load wires are at the bottom; fit the rod assembly into the handle of the closed switch assembly.
10. Secure the actuator with socket head capscrews (4) and lock washers (4); reconnect the ground wire to the lower left screw; tighten to 25-30 in-lbs (2.8-3.4 Nm).
11. Connect the black lead to the circuit breaker and the red and white leads to the capacitor terminals (red to C1 Terminal 1; white to C1 Terminal 2, or C2 Terminal 2 if two capacitors).
12. Replace the capacitor end caps and install the capacitors in the brackets; use wire ties on the actuator leads.
13. Check switch operation and actuator rod alignment by manually opening and closing both switch assemblies; secure the plastic cover.
14. Reconnect the starting battery and power sources and test the switch for proper operation.

⚠ AC power within the cabinet presents an electrical shock hazard. Disconnect all sources of AC power from the transfer switch before servicing.

1. Disconnect both Source 1 and Source 2 and the genset starting battery (negative lead first).
2. Remove the capscrew, flat washer, and lock washer securing a rod end assembly to the actuator rod; remove the rod end assembly and slide the rod out.
3. Remove the twelve machine screws securing the three plastic switch covers and lift off the covers.
4. Separate the actuator lead wires from the wiring harness; remove wire ties as required.
5. Pry the capacitors loose; disconnect the red and white leads from the capacitor terminals.
6. Disconnect the black actuator lead from the circuit breaker and the ground wire from the end of the actuator.
7. Remove the hardware securing the actuator to the switch assemblies and lift out the spacers and actuator motor.
8. Hold the actuator motor and spacers (4) in position over the switch assemblies with lead wires at the bottom.
9. Secure the actuator motor with hex head capscrews (4), lock washers (4), and flat washers (4); tighten to 70-75 in-lbs (7.9-8.5 Nm).
10. Connect the black lead to the circuit breaker and the red and white leads to the capacitor terminals.
11. Replace the capacitor end caps and install the capacitors; connect the ground wire and secure leads with wire ties.
12. Place the plastic switch covers in position and tighten to 25-30 in-lbs (2.8-3.4 Nm).
13. Insert the actuator rod into the motor, secure the rod end assembly to 70-75 in-lbs, and fit into the handle of the closed switch assembly.
14. Reconnect the starting battery and power sources; test and close the cabinet.