Kohler 15RMY Generator Set

Tools: Frequency counter

1. While observing the frequency counter, slowly increase engine speed (adjusting the engine governor) just to the point where the set shuts down. Note the frequency reading just prior to shutdown.
2. Reading shall be within: 50 Hz Sets 60 + 2 Hz; 60 Hz Sets 70 + 2 Hz.
3. Readjust the governor slightly to reduce engine speed, preventing an immediate shutdown upon restart.
4. Turn the controller main switch to OFF position and reset the overspeed fault.
5. After restarting the set, readjust the engine speed governor for the set's specified output frequency.
6. If the set fails to pass this test, perform Overspeed Shutdown Adjustment (Pot. 5).

⚠ Do not exceed 285 Volts when adjusting Pot. 2. Regulator board damage may result.

Tools: AC voltmeter

1. While observing AC voltmeter reading, slowly adjust Pot. 2 just to the point where the generator set shuts down. Note the reading just prior to shutdown.
2. Reading shall be within: 50 Hz Sets 257 + 5 Volts AC; 60 Hz Sets 280 + 5 Volts AC.
3. Readjust Pot. 2 about 1/8 turn in the CCW direction to prevent an immediate shutdown upon restart.
4. Turn controller main switch to OFF position and reset the overvoltage fault.
5. Restart the generator set.
6. Adjust Pot. 2 while observing the AC voltmeter; adjust for a meter reading as specified for this set.
7. If the set fails to pass this test, perform Overvoltage Shutdown Adjustment (Pot. 6).

⚠ High voltage is present at regulator board P1 connector and terminal strip when set is running.

⚠ Do not exceed 285 Volts when adjusting Pot. 2; regulator board damage may result.

Tools: AC voltmeter, 0-300 V AC, ±0.5%, Frequency counter, 45-75 Hz, ±1%, Potentiometer adjustment tool or small blade screwdriver, Load bank (for boards with Pot. 4 — Load Shed)

1. Disconnect generator from load; place main switch OFF and lift enclosure cover.
2. Check wire jumpers on regulator board and arrange per Table 3-1/3-2 (J1, J2, J3).
3. For single-phase connection, lift lead V9 from controller board terminal strip and insulate.
4. Adjust external voltage adjustment potentiometer to approximate midpoint of range.
5. Connect AC voltmeter and frequency counter between leads V7 and V8.
6. Break adjustment seals on Pots. 1, 2 and 3.
7. Turn Pot. 1 full clockwise and Pot. 2 full counterclockwise.
8. Start generator set with no load.
9. Adjust Pot. 2 (Volt Adj.) for the specified output voltage.
10. Observe LED; if flickering, alternately adjust Pot. 3 and Pot. 1 until steady glow.
11. Perform overvoltage shutdown check and adjustment (Pot. 6) per 50/60 Hz limits.
12. Perform overspeed shutdown check and adjustment (Pot. 5) per 50/60 Hz limits.
13. On NFPA models, check voltage adjustment range (at least ±10 Volts).
14. Seal Pots. 1, 2 and 3 with insulating varnish.

⚠ DANGER OF ELECTROCUTION! High voltage is present at regulator board P1 connector and terminal strip when set is running.

Tools: AC voltmeter 0-300 V AC, +0.5% accuracy, Frequency counter 45-75 Hz, +1% accuracy, Potentiometer adjustment tool or small blade screwdriver, Load bank

1. Disconnect generator from load. Place generator main switch in OFF position. Lift enclosure cover to expose voltage regulator board and terminal strip.
2. Check the wire jumpers on the regulator board and arrange as noted in the jumper condition table (J1, J2, J3).
3. For single-phase connection, lift lead V9 from terminal strip and insulate lead end with electrical tape.
4. Adjust the external voltage adjustment potentiometer to the approximate midpoint of its adjustment range.
5. Connect AC voltmeter and frequency counter between leads V7 and V8.
6. Break adjustment seals on Pots. 1, 2 and 3.
7. Turn Pot. 1 to full clockwise (CW) position; turn Pot. 2 to full counterclockwise (CCW) position.
8. Start the generator set with no load applied.
9. Adjust Pot. 2 (Volt Adj.) while observing the AC voltmeter; adjust for a meter reading as specified for this set.
10. Observe LED; if flickering, alternately adjust Pot. 3 (Volt Stb.) then Pot. 1 (FR Damp) until a steady glow is attained.
11. Perform Overvoltage Shutdown Check (Pot. 6).
12. Perform Overspeed Shutdown Check (Pot. 5).
13. Regulator calibration complete. Turn main switch to OFF and wait until set shuts down. Seal Pots. 1, 2 and 3 with insulating varnish.

⚠ DANGER OF ELECTROCUTION! High voltage present when set is running.

Tools: AC voltmeter 0-300 V, Frequency counter 45-75 Hz, Potentiometer adjustment tool

1. Disconnect generator from load. Place main switch OFF.
2. Check wire jumpers on regulator board per Table 3-1.
3. For single-phase, lift lead V9 and insulate.
4. Connect AC voltmeter and frequency counter between V7 and V8.
5. Start generator with no load.
6. Adjust Pot. 2 for specified output voltage.
7. Observe LED; adjust Pot. 3 and Pot. 1 for steady glow.
8. Seal pots with insulating varnish.

Tools: Ohmmeter

1. Disconnect V7, V8 and V9 from terminal strip and insulate.
2. Disconnect load leads and insulate (separately excite under no load).
3. Disconnect brush leads F1 and F2 at quick disconnect.
4. Check brush assembly for weak springs, loose holder, sticking brushes or improper alignment.
5. Check continuity between quick disconnect point on each brush lead and its adjacent slip ring; repair or replace if faulty.

⚠ See Safety Precautions before making any battery connections.

Tools: Fast Check and harness (A-291930 and 269955), Variable low voltage DC power supply, 0-50 Volt, 3 amp minimum, Stopwatch

1. Unplug harness connector inside meter box.
2. Connect Fast Check Harness to harness connector inside meter box (connectors are keyed).
3. Push wiring harness connector onto plug at top of Fast Check.
4. Move Generator Main Switch on controller to OFF.
5. Move Fast Check engine switch to OFF.
6. Clip red (+) and black (-) harness leads to 12-Volt battery or DC power supply.

⚠ HIGH VOLTAGE! Remove rings, watches and jewelry that can cause short circuits. Do not touch electrical equipment when standing in water, on wet ground, or when your hands are wet.

Tools: 208-240 Volt AC power source, On-Off switch, Pre-tested SCR module, 120 or 240 Volt AC light bulb and socket, Jumper wires

1. Connect regulator board to a good, pre-tested SCR module.
2. Wire a 120 or 240-Volt AC light bulb across (+) and (-) of SCR module.
3. Wire on-off switch (in open position) in series with AC power source.
4. Wire 208-240-Volts to V7 and V8 on terminal strip in regulator/terminal strip tray.
5. Close switch to apply power; lamp should light. Adjust Pot. 2 to clockwise limit (max intensity); counterclockwise limit extinguishes bulb.
6. Connect battery (+) to the P terminal and battery (-) to common wire between hour meter and reset lamp.
7. Turn on AC and DC power and adjust overspeed Pot. 5 counterclockwise until reset lamp turns on. Return Pot. 5 1/8 of a turn clockwise.
8. Reset fault. Turn overvoltage Pot. 6 counterclockwise until reset lamp comes on. Return Pot. 6 1/8 of a turn clockwise.
9. If above test indicates a faulty regulator board - replace and refer to new board adjustment procedure.

⚠ The SCR module may be damaged if this step is performed incorrectly. Be sure to connect the NEGATIVE (-) lead of the battery to the POSITIVE (+) pin on the SCR module.

Tools: Ohmmeter (RX1 scale), 12-Volt DC source, 100-500-Ohm resistor, 12-Volt lamp, Momentary jumper

1. Check SCR Module with ohmmeter on RX1 Scale.
2. Connect ohmmeter from (+) to (-): high resistance in one direction and low resistance in the other.
3. Connect ohmmeter from AC1 to (+): high resistance in both directions. Repeat for AC2.
4. Connect ohmmeter from AC1 to (-): high in one direction and low in the other. Repeat for AC2.
5. G1 to (+) should see low resistance in one direction and higher in the other. Repeat for G2.
6. Connect negative (-) lead from DC source to positive (+) pin on SCR module.
7. Connect positive (+) lead from DC source, with lamp in series, to AC1 pin on SCR module. Lamp should not glow.
8. Momentarily connect jumper, with resistor in series, from positive of DC source to G1 pin. Lamp should glow and continue to glow after removing jumper.
9. Repeat steps 8 and 9 with AC2 and G2. If any check indicates a faulty SCR module - replace.

⚠ EXPLOSIVE GASES! When working in an enclosed area, auxiliary battery should be located at least 18 inches above the floor.

Tools: Voltmeter, Ammeter

1. Disconnect and insulate V7, V8, V9, VO and V4 from terminal strip. Disconnect and insulate L1, L2 and L3.
2. Disconnect exciter leads F1 and F2 at quick disconnect.
3. Place a voltmeter across F3 and F4. Connect an ammeter in series with F3. Start unit and read battery voltage.
4. Ammeter should read 4/10 of 1 amp. If voltage is not present, problem is in controller. If current is high or low, problem is in the exciter field.
5. Check L1, L2, L3, V7, V8, V9, VO and V4 with a voltmeter for output (25-35 volts). If no voltage, refer to No Output checks.
6. If there is output, check the Automatic Voltage Regulation (AVR) circuit.

⚠ HIGH OUTPUT VOLTAGE DURING TESTS MAY ENDANGER HUMAN LIFE OR DAMAGE EQUIPMENT! Disconnect generator from load when troubleshooting.

Tools: 12-volt battery, DC ammeter, Ohmmeter

1. Disconnect and insulate L1, L2, L3, V7, V8, V9, VO and V4.
2. Connect brush leads in series with a 12-volt battery and DC ammeter as shown in Figure 3-2.
3. Record ammeter reading.
4. Start unit and observe ammeter; reading should remain the same.
5. If current increases considerably, a running short in the rotor has been detected. If current drops to zero, an open rotor is indicated.
6. If tests show shorted or open rotor - replace.
7. While unit is running check L1, L2, L3, V7, V8, V9, VO and V4 for AC output.
8. If any winding shows no output - repair or replace stator. If output reading is correct, problem is in the Automatic Voltage Regulation (AVR) circuit.

Tools: Voltmeter, Ammeter

1. Disconnect and insulate V7, V8, V9, VO and V4 from terminal strip; disconnect and insulate L1, L2 and L3.
2. Disconnect exciter leads F1 and F2 at quick disconnect.
3. Place voltmeter across F3 and F4; connect ammeter in series with F3.
4. Start unit and read battery voltage; ammeter should read 4/10 of 1 amp.
5. If voltage is not present, problem is in controller; if current is high or low, problem is in the exciter field.
6. Check L1, L2, L3, V7, V8, V9, VO and V4 with a voltmeter for output (25-35 volts).
7. If there is output, check the Automatic Voltage Regulation (AVR) circuit.