Installation and Operation Instructions

1.1 Install the generator sets and current transformers (CTs).

1. Install the generator sets according to the instructions and diagrams in the generator set Installation Manual. Do not connect wiring to the transfer switch at this time.
2. Identify the generator sets as generator 1 and generator 2. Use the provided decals to label them. Be careful to keep track of generator 1 and generator 2 during installation and connection.
3. Install one current transformer (CT) (GM86609) inside each generator set enclosure, below the customer-connection terminal block in the air intake area.
   1. Load lead L1 from the generator should enter the CT on the side with the dot. (See Figure 5)
   2. Load lead L2 must pass through the CT in the opposite direction from L1. (See Figure 5)

   Do not operate the paralleling system without the CTs in place. CTs measure power on each generator to allow load sharing.

4. Connect the CT harness to connector P3 on the RDC2 controller inside the generator set. (See Figure 6)

Figure 5: Load Lead Routing through Current Transformer (CT) - Shows L1 and L2 passing through a CT. The dot on the CT indicates the direction for L1. Emergency leads must cross through the CT in opposite directions.

Figure 6: Current Transformer and Adaptor Harness Connections to RDC2 - Diagrams illustrating connections to the RDC2 controller, including adaptor harness to P2 and CT connection to P3.

1.2 Install the automatic paralleling module (APM).

7. To remove the enclosure's front panel, support it while removing screws. Pull the bottom out and down until the top clears the enclosure. Remove the inner panel to access APM components.
8. Refer to Section 8 for recommended cable entrance areas. Cover internal components. Punch or drill cable entry openings in the APM enclosure.
9. Use a vacuum cleaner to remove debris from the enclosure. Do not use compressed air, as it can lodge debris and damage components.
10. Mount the enclosure to a wall or other rigid vertical structure using the provided mounting holes. Use shims to plumb the enclosure. Mounting holes have gaskets to seal out moisture. Use washers with screws to prevent gasket damage.

Figure 8: Adaptor/Protection Harness GM86610 (provided) - Diagram of the harness.

1.3 Install the circuit breaker kit, if required.

Circuit breaker kits may be required if the APM is not installed within sight of the generator sets. Ensure compliance with NEC and local codes. If kits are not used, proceed to Section 1.4.

11. Install circuit breaker mounting bracket GM85151 onto the back wall of the APM enclosure:
    1. Remove 4 screws X-67-133 and 8 washers X-25-36 from the back wall. Save screws; discard washers. (See Figure 9)
    2. Align bracket mounting holes with enclosure holes.
    3. Secure the bracket with the removed screws.
12. Mount two circuit breakers onto the bracket.
    • For 14RESA (70 amp breakers): Use 4 X-67-132 screws and 4 X-400-145 spacers per breaker, placing spacers between mounting tabs and bracket. (See Figure 10) Connect breakers to APM contactors using 4 leads LN-0607-0606. (See Figure 9 and Section 8 wiring diagram)
    • For 20RESA or 20RESB (100 amp breakers): Use 2 X-67-132 screws per breaker. (See Figure 11) Connect breakers to APM contactors using 4 leads LN-0407-0606. (See Figure 9 and Section 8 wiring diagram)
13. Remove knockouts for circuit breakers in the inner cover of the enclosure. (See Figure 9 and Figure 12)
    • For 70 amp breakers (14RESA): Remove the larger portion on the left side of each knockout.
    • For 100 amp breakers (20RESA/20RESB): Remove both portions of each knockout.
14. Attach the GENERATOR 1 and GENERATOR 2 decals above the circuit breakers as shown in Figure 9. (Decals are provided in the literature bag with the APM).
15. Attach the Service Disconnect decals to the outside of the inner cover near the circuit breaker openings, correctly labeling them for Generator 1 and Generator 2. (See Figure 13 and Figure 9)
16. Close the circuit breakers between the APM and the generator sets.

The inner door for the APM enclosure will be installed later.

Figure 9: Circuit Breaker Kit Installation Inside the APM Enclosure - Shows internal components, labels, and installation steps.

Figure 10: 70 Amp Circuit Breaker Mounting, 14RESA - Diagram showing mounting bracket, spacers, screws, and 70A circuit breaker.

Figure 11: 100 Amp Circuit Breaker Mounting, 20RESA and 20RESB - Diagram showing mounting bracket, screws, and 100A circuit breaker.

Figure 12: Circuit Breaker Knockouts - Diagrams illustrating knockout removal for different breaker sizes.

Figure 13: Decals provided with APM - Shows Generator 1, Generator 2, and Service Disconnect decals.

1.4 Install the Model RXT transfer switch.

Only one transfer switch can be used.

17. Install the ATS according to the installation instructions and dimension drawings in the transfer switch Installation Manual.
18. Do not connect the emergency source wiring or the RBUS connections until instructed later in this procedure.

1.5 Install the LCM or load shed kit and optional PIM, if used.

One PIM and one LCM or load shed kit can be used. Multiple PIMs, LCMs, or load shed kits cannot be connected.

19. Follow the installation instructions provided with the PIM and LCM or load shed kit(s).

Connect sufficient non-critical loads to the LCM or load shed kit so that one generator set can support the remaining load, if necessary.

Do not install the CT provided with the LCM or load shed kit. The generator controllers have built-in metering with the locally mounted CT installed in Section 1.1.

2.1 Voltage Sensing

4. Connect voltage sensing leads from both adaptor harnesses (installed in step 5) to terminal block TB1 in the APM. (See Figure 9 and Figure 14)
   1. Connect voltage sensing lead V9 (RDC2 P2-8) from Generator 1 to TB1-1, labeled V9A, in the APM enclosure.
   2. Connect voltage sensing lead V9 (RDC2 P2-8) from Generator 2 to TB1-2, labeled V9B, in the APM enclosure.

Figure 14: Voltage Sensing Connections - Diagram showing connections from Generator 1 and Generator 2 to TB1-1 (V9A) and TB1-2 (V9B) respectively.

2.2 RBUS Communication Connections

RBUS communication wiring to the APM must connect directly to the generator sets (See Figure 7). Other accessories (PIM, LCM, load shed kit) connect after the APM.

Measure cable length from the furthest generator set to the last RBUS device and compare to Figure 15. Maximum cable length depends on the number of optional modules (APM, RXT, PIM, LCM, load shed kit).

For RBUS connections A and B to APM, RXT, LCM, and/or PIM, use 20 AWG shielded, twisted-pair cable (Belden #9402 or #8762 recommended). For outdoor/buried installations, use outdoor-rated Belden #1075A or equivalent.

For PWR and COM connections from TB1 to RXT, PIM, and/or LCM, use the second pair in a two-pair cable for short runs, or 12-14 AWG cable for longer runs (See Figure 15).

All communication cables must be routed through conduit, separate from power cables.

5. Connect RBUS communication cables (A, B, PWR, and COM terminals). (See Figure 16)
   1. Connect RBUS from Generator 1 RDC2 controller to APM diode board terminal P21 (GEN 1).
   2. Connect RBUS from Generator 2 RDC2 controller to APM diode board terminal P20 (GEN 2).
   3. Connect P10 on the APM PIB circuit board to the RXT interface board. (See Figure 16)
   4. If PIM and/or LCM are used, connect communication cables from the RXT to the accessory modules per their instructions.
   5. Connect communication cable shields as shown in Figure 16, leaving one end disconnected.

* Use 12 or 14 AWG cable for PWR and COM connections only. For RBUS connections A and B, use shielded, twisted pair communication cable specified above.

Figure 15: Maximum Communication Cable Lengths for Connection of RBUS Modules to the APM

Figure 16: Communication (RBUS) Connection Details - Diagrams showing connections between APM PIB, Diode Board, RXT, PIM, and LCM/load shed kit.

2.3 AC Voltage Output Connections

6. Connect generator set AC output leads to the APM contactors or to the circuit breakers (if installed per Section 1.3). Connect generator 1 to contactor 1 and generator 2 to contactor 2 in the APM. (See Figure 17 or Figure 33 wiring diagram) If optional circuit breakers are used, connect to them instead of the APM contactors.
   1. Connect L1 from generator 1 to 1L1 at APM contactor 1. Connect L2 from generator 1 to 3L2 on APM contactor 1.
   2. Connect L1 from generator 2 to 1L1 at APM contactor 2. Connect L2 from generator 2 to 3L2 on APM contactor 2.

   L1 and L2 polarity is important. Reversing these leads is a common cause of auto-discovery failure.

7. Connect the GEN LOAD A, GEN LOAD B, and NEUTRAL lugs in the APM to the emergency source lugs on the RXT transfer switch. (See Figure 33 wiring diagram)

Figure 17: Generator Output Connections to APM Contactors (optional circuit breakers not shown) - Diagram showing connections from Generator 1 and Generator 2 to Contactor 1 and Contactor 2 respectively, including L1 and L2 terminals.

2.4 Ethernet Connection for OnCue Plus

8. If OnCue® Plus is used, connect both RDC2 controllers to the Internet via the Ethernet modem or router on site. Refer to the generator set Installation Manual for Ethernet cable location.

3.1 Secure the APM enclosure and reconnect power to the generator sets.

1. The APM's NEMA 3R enclosure has a locking tab. Turn it out while the enclosure is open so the door can be locked with a padlock.
2. Install the inner door on the APM enclosure.
3. Install the APM enclosure door and lock it with a customer-supplied padlock.
4. Reconnect the generator set engine starting batteries, negative (-) lead last.
5. Reconnect utility power to the generator sets.

3.2 Load firmware onto each generator set controller.

A personal computer (laptop) with Kohler SiteTech™ software is required for system installation and setup. SiteTech™ software is available to Kohler-authorized distributors and dealers.

Use a personal computer and Kohler SiteTech™ software to load RDC2 paralleling firmware version 105.4 or higher. Download from TechTools and save on the laptop. Refer to TP-6701, SiteTech Software Operation Manual, for instructions. Load the firmware onto both generator sets' RDC2 controllers.

Standard RDC2 controller firmware cannot be used on paralleled generator sets. Paralleling firmware is required.

Choose one generator set as the primary device. It will control other RBUS devices (RXT, PIM, LCM). The other set is secondary.

1. Save the paralleling firmware file to your computer (e.g., RDC2_###_#.bin).
2. Connect the laptop PC to the primary generator set's RDC2 controller via USB. Open SiteTech program.
3. Load the paralleling firmware onto the generator set's RDC2 controller. (See TP-6701 for instructions)
4. Repeat steps 2 and 3 for the secondary generator set.
5. Check the firmware version on each controller to verify version 105.4 or higher is loaded. (See generator set operation manual for instructions)
6. If OnCue Plus will be used, refer to the OnCue Plus Operation manual to set the password on each RDC2 controller.

3.3 Set the time, date, and exercise schedule on the primary generator set.

1. The RDC2 display will prompt you to set the primary generator set. After firmware update, "RBUS Primary?" will appear.
   1. Use up/down arrows to select TRUE for the chosen primary generator set.
   2. Select RBUS Primary? FALSE on the other generator set.
2. Follow the generator set installation manual to set time, date, and exercise on the primary generator set only. The primary set communicates these to the secondary set.
3. Proceed to Section 4, Setup and Commissioning.

4.1 Verify communication connections.

Check Network Information and Remote Devices menus on the RDC2 controller, or use Kohler SiteTech to check RBUS Devices group parameters.

1. Verify the primary controller recognizes the secondary controller as a "Kohler Power Generation Device."
2. Check that the serial number of the Kohler Power Generation Device seen in the primary controller matches the secondary controller's serial number. The secondary controller will not see the primary controller as an RBUS device.

The controller serial number can be found in the RDC2 controller's Genset Information menu.

4.2 Set up the LCM or load shed kit.

1. Check that the primary controller sees the LCM or load shed kit as an RBUS device. Check Network Information and Remote Devices menus on the RDC2 controller, or use Kohler SiteTech to check RBUS Devices group parameters.
2. Use SiteTech software connected to the primary controller to set the following parameters on the LCM:
   1. Set Genset Maximum Percent Capacity on the LCM or load shed kit higher than the APM Automatic Stop Minimum Percent setting. (See Figure 21 for APM settings)
   2. Set Generator Overload Percent on the LCM or load shed kit at least 20% higher than the APM Automatic Stop Minimum Percent Load setting.

See instruction sheets TT-1574 for LCM or TT-1609 for load shed kit, if necessary.

4.3 Set up the PIM, if equipped.

If the system does not include a programmable interface module (PIM), proceed to Section 4.4.

1. If an optional PIM is connected, check that the primary controller sees it as an RBUS device. Check Network Information and Remote Devices menus on the RDC2 controller, or use Kohler SiteTech to check RBUS Devices group parameters.
2. Use SiteTech software connected to the primary controller to set up PIM inputs and outputs. See TT-1584 (provided with PIM) for default settings. See TP-6701, SiteTech Software Operation manual, for instructions to change settings.
3. Set PIM settings on the secondary controller to match the primary controller's PIM settings. Although the secondary controller only reads system status, matching PIM configuration ensures primary status can be switched between controllers.

4.4 Perform the auto-discovery procedure.

This procedure is REQUIRED.

1. Close circuit breakers on both generator sets and in the APM (if equipped with optional kit).
2. Press OFF on generator set 2. Press RUN to start generator set 1.
3. After generator 1 starts, the controller cycles relays in the APM to recognize the output driving the contactor that connects the generator to the paralleling bus. Contactor status may display the wrong generator until auto-discovery is complete.
4. Verify the connection LED on the APM lights up, indicating the generator set is connected. It will turn on, off, on again, and remain on if the correct output is detected. The controller remembers which contactor is associated with the generator after successful connection.
5. Press OFF to stop generator set 1. Press RUN to start generator set 2. Repeat steps 3 and 4 for the other generator to verify relay cycling.

Troubleshooting Auto-Discovery

If the connection LED on the APM fails to illuminate or relays do not cycle, check the following:

• Check wiring between the generator and APM, paying special attention to L1 and L2 connections.
• Check connection of the sensing wire to V9 on the generator wiring harness. (See Figure 14)
• Verify generator 1 is connected to contactor 1 and generator 2 to contactor 2 in the APM.

If relays continue to cycle after ATS indicates availability, check wiring to both generator sets, especially from V9A and V9B on APM transformers to V9 terminals on generator controllers. This connection is necessary for auto-discovery of output contacts.

If correct output is detected (on, off, on, remain on), but output continues to cycle, verify L1 and L2 connections are correct from generator to APM and consistent throughout the APM. Ensure APM wiring has not been modified, as bus sensing must be accurate.

In SiteTech™, observe Generator Voltage L2-L3 parameter. It should match generator voltage L1-L2 when the contactor is closed, and read 0 volts when open. If L2-L3 reads over 200 volts when both contactors are open, reverse L1 and L2 connections between that generator and the APM.

4.5 Verify synchronization and calibration.

1. Start generator 1 by pressing RUN on the RDC2 controller.
2. When the generator reaches rated voltage and frequency, verify the corresponding contactor in the APM closes.
3. Verify the Generator Rotation Actual parameter (in SiteTech Generator Metering) reads between -300 and 300 (-30° and 30° phase angle across the closed contactor). If outside this range, Generator 1's RDC2 controller is not sensing bus direction accurately.
4. Calibrate voltage metering on Generator 1.
5. Calibrate bus metering (Generator Voltage L2-L3). Always calibrate bus voltage with the generator running and paralleling contactor closed.
   1. Bus metering should match calibrated generator metering. It is normal for bus voltage to vary more than generator voltage. Match average bus voltage reading to generator voltage.
   2. Increase Genset Calibration Factor Voltage L2-L3 to increase measured bus voltage.
   3. Decrease Genset Calibration Factor Voltage L2-L3 to decrease measured bus voltage.
6. Stop generator 1 and repeat steps above for generator 2.
7. After synchronization checking, stop both generators and place them in Auto. (Note: generators will start if utility is not present on the ATS).

4.6 Verify current metering.

1. Ensure both generator sets are in AUTO mode.
2. Open the utility source breaker to the ATS to simulate utility power loss. A loaded exercise can also be used.
3. Verify generators start, synchronize, and close both contactors. This enables controllers to verify metering. Engines may appear slightly unstable during verification.
4. Once complete, the ATS will transfer. Metering is now verified. Metering verification only needs to be performed once. Subsequent utility losses will result in more timely ATS transfers.
5. Close the utility source circuit breaker or wait for loaded exercise to end. Verify ATS transfers to utility and both generator sets shut down.
6. Verify both generator sets are in AUTO mode after commissioning is complete.

Troubleshooting Current Metering

If a generator shuts down with "No Current Shutdown" displayed, verify AC output wires cross through the CT in opposite directions (See Figure 5) and the CT is connected to the generator controller at P3. Correct and retry the current metering test from Section 4.6, step 1.

The message "ErraticSig Shutdown Current Metering" indicates unstable current readings. Otherwise, the controller has successfully determined CT connection direction when the ATS transfers.

4.7 Final adjustments.

At this point, the paralleling system can provide power to ATS-connected loads. Further adjustment of gains and windows for optimal performance can be done if desired.

See Section 5.3.2, Order Selection Method, for instructions on manually setting generator set order of operation or selecting the runtime hours method, which balances operation times based on hours on each set. Runtime hours method is the default.

5.1 Synchronization and Paralleling

The RDC2 controllers on Generator 1 and Generator 2 manage synchronizing and paralleling. Each controller adjusts to synchronize with the other and share real/reactive load once both are online. The process starts after the generator reaches rated voltage and frequency and consists of 3 steps:

1. First-on determination
2. Synchronizing
3. Paralleling

These steps are described in the following sections.

5.2 Primary and Secondary Controllers

Generator set controllers are designated primary and secondary.

The RBUS primary controller initiates all RBUS communication.

• The primary controller operates all RBUS modules (RXT, PIM, LCM).
• The primary controller reads status from all RBUS modules.
• If the primary controller loses power, RBUS communication for the paralleling system is lost.

The RBUS secondary controller responds to requests from the primary controller.

• The secondary controller monitors RBUS activity but cannot control RBUS devices.
• The secondary controller receives generator management information from the primary controller.
• The secondary controller can only change the state of the secondary generator's contactor if the primary controller requests it to close.

Primary and secondary controller designations change if AUTO-OFF is pressed on the primary controller. (See Section 5.3.2)

5.3 Generator Management

The paralleling system performs generator management as follows:

• If one generator fails to start, the other remains online and supplies loads it can support. The LCM or load shed kit sheds loads exceeding the generator set's capacity.
• After both generators connect to the load, one will disconnect and shut down if not needed for 5 minutes. If an LCM or load shed kit is connected, the generator stops 5 minutes after all loads are added. Minimum stop time is 5 minutes without load management, 11 minutes with it.
• Generator management logic alternates generator set operation to equalize run times.
• Operating order changes if generator set run times differ by more than 24 hours.
• Generator management logic is solved in the primary controller. Configuration is verified in the secondary controller upon connection; a message warns of differences.
• The primary controller can overwrite configurations in attached devices. Changing a setting on the primary controller changes it on both.

5.4 Generator Set Maintenance

To perform maintenance or service on generator sets, remove one generator set from the system at a time using this procedure:

1. On the generator set to be serviced, press AUTO and OFF buttons on the RDC2 controller simultaneously for about 1 second.
2. Wait for the generator set to shut down. Turn off non-critical appliances to reduce load, if necessary.
3. Press OFF to shut down the generator set, if necessary.
4. Disconnect utility power to the generator set.
5. Disconnect the generator set battery, negative (-) lead first.
6. Follow instructions in the generator set manual for service.
7. Reconnect the generator set battery, negative (-) lead last.
8. Reconnect utility power to the generator set.
9. Press AUTO and RUN buttons on the RDC2 controller simultaneously to return the system to runtime hours mode, if desired.

5.5 Faults

Fault messages displayed on the RDC2 controller are shown in Figure 22 and Figure 23.

To clear warnings in Figure 22, press AUTO or OFF.

• Press AUTO to clear the fault without shutting down the generator set.
• Pressing OFF clears the fault AND stops the generator set.

LossOfComAPM Fault

A possible cause is the primary controller being powered down. If powered off without using the AUTO-OFF sequence (Section 5.3.2), the paralleling system will not function. To restore function, go to the secondary controller's Communications menu, RBUS network. Set RBUS primary to True on the secondary controller. When the former primary controller powers up again, set RBUS Primary? to False.

* Pressing OFF will stop the generator set.

Figure 22: Warning Messages (protective relay disconnect)

Figure 23: Other Events

5.6 Status Indicators

The APM has an LED panel indicating system status. (See Figure 24 and Figure 25)

A Model RXT transfer switch is required for power connection status indication. (See Figure 25)

Figure 24: Status Indicators - Diagram showing LED indicator locations on the APM panel.

* Model RXT transfer switch is required for operation of these LEDs.

Figure 25: LED Operation/Status Indication

Breaker will not close in RUN.

Check whether the other generator set is connected to the paralleling bus.

• NO: Auto-discovery is not complete. Initiate auto-discovery. Generator must be running in RUN mode (not AUTO). Other generator must be stopped with controller in OFF mode (press OFF button).
• YES: Other breaker is closed. Stop the other generator set.

Check whether the generator sees bus voltage (L2-L3 in SiteTech) above 25% of rated voltage.

• NO: Bus sensing is not connected or is connected incorrectly. Check wiring between both generators and the Automatic Paralleling Module.
• YES: (Proceed to next check)

Figure 28: Troubleshooting: Breaker Will Not Close - Flowchart for diagnosing breaker closure issues.

SiteTech indicates that both engines are under load, but the ATS has not transferred.

Transfer ATS and start each generator individually. Does the metering read positive power with load on the generator?

• NO: The metering on this generator is backwards. Select a different model number for the generator, then re-select the correct model number. This will clear the CT direction flag and allow generators to re-determine CT direction.
• YES: The metering on this generator is correct. Start the other generator and allow it to close to the bus, then stop this generator. Check that the other generator is reading positive power.
  • NO: The metering on the other generator is backwards. Select a different model number for the other generator, then re-select the correct model number. This will clear the CT direction flag and allow the generators to re-determine CT direction.
  • YES: Both generators are metering accurately; the load indicated in SiteTech must be due to electrical noise. Continue to commission the system.

Figure 29: Troubleshooting: ATS Has Not Transferred - Flowchart for diagnosing ATS transfer issues.

Auto-discovery does not complete.

Check whether the Automatic Paralleling Module indicates that the generator is closed to the bus.

• NO: The wait for auto-discovery can be as long as 30 seconds. After 30 seconds expires, try to close the contactor manually (jump L1 to the C wire on the coil). Check if it closes. If it closes, the device may have auto-discovered to a different contactor. Set the engine model number select to a different model and then set it back. This will clear any auto-discover information stored in the controller.
• YES: (Proceed to next check)

Is the generator circuit breaker tripped?

• YES: Reset the generator circuit breaker.
• NO: (Proceed to next check)

Is the APM circuit breaker tripped?

• YES: Reset the circuit breaker in the APM.
• NO: (Proceed to next check)

Check for bad connections between the generator and APM. Pay special attention to the Neutral connection.

• NO: Correct the connections.
• YES: (Proceed to next check)

Check that the APM is recognized on RBUS. Connection status of each module can be found on the front panel of the controller.

• YES: Check the RBUS connections and follow RBUS troubleshooting procedures if the module is not visible in the list.
• NO: The controller thinks that the bus is live (will not close to a live bus in auto-discovery mode). Check wiring between the generator and the APM. Pay special attention to the V9 lead connection, as this is the bus sensing.

Check if the generator controller is seeing bus voltage (look at L2-L3 voltage in SiteTech).

• YES: (Proceed to next check)
• NO: The other generator is not in OFF. Press the OFF button on the other generator. Then start this generator in run mode.

The controller has a fault or warning.

• YES: Clear fault to retry. See Fault listing for additional information on which faults inhibit breaker closure.
• NO: (Proceed to next check)

Controller is not running paralleling code.

• YES: Load paralleling firmware RDC2_APM_###.#.bin onto both generator set controllers and cycle power when complete.

Figure 30: Troubleshooting: Auto-discovery - Flowchart for diagnosing auto-discovery failures.