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Cummins/Onan DQAB Generator Set

The Cummins/Onan DQAB is a 250 kW Diesel standby generator set powered by a Cummins/Onan M11 engine. It is available at 480/277 V, 208/120 V and 240/120 V, 3-phase, 60 Hz and rated 12 A. It holds about 36 L (9.5 gal) of oil and 49 L (12.9 gal) of coolant. Starting uses 2 group-8 batteries rated 1400 CCA at 24 V. The set measures 5486×1676×2515 mm (216.0×66.0×99.0 in), weighs about 5815 kg (12820 lb) and produces 75 dBA at 7 m. An integrated tank holds 1040 L (274.7 gal).

250 kW
Standby
10.8 L
Displacement
36.0 L
Oil capacity
3
Document types

How to read your Cummins/Onan serial & model number →

Typical fuel consumption for 250–255 kW Diesel generators →

Compare with other 250–255 kW Diesel generators →

Service parts for the DQAB

Grouped by system, with how many of each the parts manual calls for.

Air intake

1 required

Prices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.

Specifications

FuelDiesel
Frequency60.0 Hz
Standby power250 kW
Prime power225 kW
ControllerPowerCommand
Oil capacity36.0 L
AlternatorS-1140
Voltage options480/277 V, 208/120 V, 240/120 V
Phase3
Rated current12 A
Battery group8D
Battery cranking1400 CCA
Battery voltage24 V
Battery quantity2
Coolant capacity49 L
Dimensions (L×W×H)5486×1676×2515 mm
Dry weight5815 kg
Sound level75.0 dBA @ 7 m
Fuel tank1040.0 L

Engine

Cummins/Onan M11
Oil capacity34.0 L
Coolant capacity12.9 L
Displacement10.8 L
Rated speed2100 rpm

Filters for the Cummins/Onan M11

7

Engine-mounted filters the filter manufacturers list for this engine family. These come from the engine, not from this generator set’s own parts list, so confirm against your serial number before ordering.

SystemFilterDescriptionCross-references
Oil filterP553000Lube Filter, Spin-On Full FlowCUMMINS 3318853, CUMMINS 3825970, NAPA 1748, NAPA 1748XD FridayParts $125.00
Oil filterP550777Lube Filter, Spin-On BypassCUMMINS 3021658, CUMMINS 33004232, NAPA 1749, BALDWIN B7577 FridayParts $43.56
Fuel filterP550105Fuel Filter, Spin-On PrimaryCUMMINS 154700, CUMMINS 154710, NAPA 3109, NAPA 3405 buy
Fuel / water separatorP558000Fuel Filter, Water Separator Spin-On Twist&DrainCUMMINS 3308638, CUMMINS 3308683, NAPA 3405, NAPA 3693 KuduParts $24.00 FridayParts $25.66
Fuel / water separatorP551000Fuel Filter, Water Separator Spin-On Twist&DrainCUMMINS 3161407, CUMMINS 3329289, NAPA 3406, BALDWIN BF1259 FridayParts $99.00
Coolant filterP552071Coolant Filter, Spin-On Sca PlusCUMMINS 299080, CUMMINS 299880, NAPA 4071, TORO 012706560 FridayParts $37.53
Coolant filterP554071Coolant Filter, Spin-OnCUMMINS 209604, CUMMINS 209606, NAPA 4071, WALGAHN-MOTORENTECHN 00811412 FridayParts $397.60

Maintenance & consumables

for the Cummins/Onan M11
ItemSpecCapacityPart #Interval
Air filter36660756000 hr Amazon eBay $129.80
Fuel filterFuel Filter—6000 hr
Oil filterOil Filter—6000 hr
Battery24V Battery—6000 hr
Belt—6000 hr
CoolantCoolant—6000 hr
Coolant filter—6000 hr
OilEngine Oil2.6 l—6000 hr
Spark plug—6000 hr

Service intervals

1
ItemActionHoursMonthsNotes
Rupture basin leak detect switchTest12 moCheck once a year; in some areas weekly inspections may be required by safety code regulations

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

60
TypeItemValueUnitCondition
ClearanceAngular alignment maximum T.I.R.0.001inch per inch of radius (center of shaft to indicator axis)measuring deflection to bolt heads
ClearanceFloat switch assembly float lift clearance below C-clip stop1/8inch (3 mm)use a feeler gauge
ClearanceGenerator-to-engine angular alignment (T.I.R.).001 in. per inch of radius (center of shaft to indicator axis), maximumin750 kW gensets and larger
GapMPU sensor to flywheel ring gear toothback it out one quarter turnturnsensor threaded in until it just touches gear tooth
OtherAngular alignment maximum T.I.R..001 inches per inch of radiusin/incenter of shaft to indicator axis
OtherBattery specific gravity, fully chargedapproximately 1.260specific gravityat 80 F (27 C)
OtherFuel lift height limit6feet(1.8 meters) between fuel lift pump and bottom of dip tube
OtherGOV GAIN default value for paralleling applications70%
OtherMaximum cranking voltage drop2voltsdifference between battery and starter terminals while cranking
OtherREG VHZ (underfrequency roll-off) adjustable range1 through 50; normal range 7 through 21
OtherStart delay adjustment range0 to 300seconds
OtherStop delay adjustment range0 to 600seconds
OtherUnder-frequency roll-off threshold (UFRO)typically 59 Hz for 60 Hz applications and 49 Hz for 50 Hz applicationsHzAVR UFRO pot preset
PressureEngine oil pressure - K19 normal50-70psi (345-482 kPa)run mode
PressureEngine oil pressure - K38 normal45-65psi (310-448 kPa)run mode
PressureEngine oil pressure - K50 normal50-70psi (345-482 kPa)run mode
PressureEngine oil pressure - L10/M11 normal30-50psi (207-345 kPa)run mode
PressureEngine oil pressure - NTA 855 normal35-50psi (241-345 kPa)run mode
PressureEngine oil pressure - V28 normal50-90psi (345-620 kPa)run mode
PressureEngine oil pressure shutdown limit - L10/M1120psi (138 kPa)run mode value
PressureEngine oil pressure shutdown limit - L10/M118psi (55 kPa)idle mode value
PressureEngine oil pressure warning limit - L10/M1112psi (83 kPa)idle mode value
PressureEngine oil pressure warning limit - L10/M1125psi (172 kPa)run mode value
PressureK19 engine idle oil pressure20psi (138 kPa)idle
PressureK19 engine normal oil pressure50-70psi (345-482 kPa)normal run
PressureK19 oil pressure shutdown/warning limitsshutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idlepsi (kPa)
PressureK38 engine idle oil pressure20psi (138 kPa)idle
PressureK38 engine normal oil pressure45-65psi (310-448 kPa)normal run
PressureK38 oil pressure shutdown/warning limitsshutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idlepsi (kPa)
PressureK50 engine idle oil pressure20psi (138 kPa)idle
PressureK50 engine normal oil pressure50-70psi (345-482 kPa)normal run
PressureK50 oil pressure shutdown/warning limitsshutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idlepsi (kPa)
PressureL10/M11 engine idle oil pressure15psi (103 kPa)idle
PressureL10/M11 engine normal oil pressure30-50psi (207-345 kPa)normal run
PressureL10/M11 oil pressure shutdown limit20psi (138 kPa)run mode value
PressureL10/M11 oil pressure shutdown limit8psi (55 kPa)idle mode value
PressureL10/M11 oil pressure warning limit12psi (83 kPa)idle mode value
PressureL10/M11 oil pressure warning limit25psi (172 kPa)run mode value
PressureLow oil pressure service limit while cranking10psiservice lubricating system if below
PressureLow oil pressure shutdown threshold14psiless than this value shuts down
PressureNTA 855 engine normal oil pressure35-50psi (241-345 kPa)normal run
PressureNTA 855 oil pressure shutdown limit25psi (172 kPa)run mode value
PressureNTA 855 oil pressure shutdown limit8psi (55 kPa)idle mode value
PressureNTA 855 oil pressure warning limit12psi (83 kPa)idle mode value
PressureNTA 855 oil pressure warning limit30psi (207 kPa)run mode value
PressureOil pressure - K19 engine idle20psi (138 kPa)idle
PressureOil pressure - K19 engine normal50-70psi (345-482 kPa)normal operating
PressureOil pressure - K38 engine idle20psi (138 kPa)idle
PressureOil pressure - K38 engine normal45-65psi (310-448 kPa)normal operating
PressureOil pressure - K50 engine idle20psi (138 kPa)idle
PressureOil pressure - K50 engine normal50-70psi (345-482 kPa)normal operating
PressureOil pressure - L10/M11 engine idle15psi (103 kPa)idle
PressureOil pressure - L10/M11 engine normal30-50psi (207-345 kPa)normal operating
PressureOil pressure - NTA 855 engine idle15psi (103 kPa)idle
PressureOil pressure - NTA 855 engine normal35-50psi (241-345 kPa)normal operating
PressureOil pressure - V28 engine idle20psi (138 kPa)idle
PressureOil pressure - V28 engine normal50-90psi (345-620 kPa)normal operating
PressureOil pressure shutdown limit - idle mode value (K19)10psi (69 kPa)idle mode
PressureOil pressure shutdown limit - idle mode value (L10/M11)8psi (55 kPa)idle mode
PressureOil pressure shutdown limit - run mode value (K19)35psi (241 kPa)run mode

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

FluidGradeStandardAmbientCapacityNotes
Coolantsoft water / E.G. / DCA mixtureCooling system to be filled with soft water/E.G./DCA mixture (on-site review checklist).
FuelDieselDay tank fuel transfer pump maintains reservoir of diesel fuel in the day tank.
GreaseLithium based greaseMobilux No. 2 or Shell Alvania R32.74 oz (81 ml)Generator end bearing. Temperature range -22F to +248F (-30C to +120C). Grease should be equally divided between the bearing, bearing cap cavity, and bearing cartridge cavity.
GreaseLithium based grease, Mobilux No. 2 or Shell Alvania R3-30°C to 120°C2.74 oz (81 ml)End bearing lubricant; grease equally divided between bearing, bearing cap cavity and bearing cartridge cavity.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Fault codes

53
CodeNameMeaningSeverityAction
101IDLE MODEIndicates that the engine is operating in idle mode. Grounding the engine idle input causes generator build-up to be inhibited and the engine to be governed at 800 RPM.WarningRemove ground from engine idle input to return to normal speed and voltage.
102EMERGENCY STOPIndicates local or remote Emergency Stop.ShutdownTurn the switch clockwise and allow it to pop out (local only); move the Run/Off/Auto switch to Off; press the Reset switch; select Run or Auto as required. Can be reset only at the PCC front panel.
200LOW OIL PRESSUREIndicates engine oil pressure has dropped to an unacceptable level.WarningIf generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow 201-SHUTDOWN procedure. Access the Oil Pressure menu prior to clearing the fault.
201LOW OIL PRESSUREIndicates engine oil pressure has dropped below the shutdown trip point.ShutdownCheck oil level, lines and filters; replenish if low; reset control and restart.
204OIL PRES SENDERIndicates that the control has sensed that the engine oil pressure sender is out of its working range.WarningCheck that the engine oil pressure sender is properly connected.
210LOW COOLANT TEMPWarning occurs when engine coolant temperature is 70°F (21°C) or lower.WarningIndicates engine coolant heater is not operating or is not circulating coolant. Check coolant heater power supply, low coolant level, and heater element current draw.
211HIGH COOLANT TEMPIndicates the engine coolant temperature is getting close to the recommended maximum temperature limit: 215° F (102° C) − standby or 207° F (97° C) − primary.WarningReduce load if possible; check air inlets and outlets and remove obstructions to airflow.
212HIGH COOLANT TEMPIndicates engine has overheated (coolant temperature has risen above the shutdown trip point: 215 F (102 C) - standby or 207 F (97 C) - primary).ShutdownCheck for obstructions to cooling airflow; check fan belt; check coolant mixture; check blower fan and circulation pumps; reset control and restart.
213COOLANT SENDERResistance of the coolant temperature sender is out of range.WarningCheck the resistance of the sender; should be 500 to 2k ohms.
214LOW COOLANT LVLIndicates engine coolant level has fallen below the trip point.WarningCheck coolant level in radiator and coolant recovery bottle; replenish if low; look for leaks.
215LOW COOLANT LVLIndicates engine coolant level has fallen below the trip point.ShutdownAllow engine to cool; check coolant level and leakage points; reset control and restart.
220MAG PICKUPMag pickup speed indication is not being sensed or does not match generator set output frequency.ShutdownRestart and check RPM; check PCC model setting; inspect and test MPU.
221FAIL TO CRANKPossible fault with control or starting system.ShutdownCheck fuse F3 on the Engine Interface board; check battery cable connections; recharge or replace the battery.
222OVERCRANKPossible fuel system problem.ShutdownCheck for empty fuel tank, leaks, plugged fuel lines; replace dirty fuel or air filter; reset and restart.
223OVERSPEEDIndicates engine has exceeded normal operating speed. (115% ±1% of nominal).ShutdownCheck mechanical fuel linkage and governor module/digital board duty cycle.
224FAIL TO SYNCHRONIZEGenerator set has not synchronized to the system bus within the allowable time frame.WarningCheck governor system stability; adjust governing and synchronizer parameters; check fuel system.
226FAIL TO CLOSEParalleling breaker has been given a signal to close, but has not closed properly.ShutdownVerify breaker charging mechanism; check close signal; verify auxiliary contact signals.
230LOW DC VOLTAGEIndicates battery voltage is below 10 VDC.WarningRecharge or replace the battery; check the battery charger fuse. Clean and tighten battery cable connections. Check engine DC alternator; replace if normal charging voltage is not obtained. Check float level if applicable.
231HIGH DC VOLTAGEIndicates battery voltage exceeds 32 VDC.WarningLower battery charger float level if applicable; check engine DC alternator.
232WEAK BATTERYIndicates battery voltage drops below 60% of nominal for two seconds, during starting.WarningSee LOW DC VOLTAGE 230.
240LOW FUEL−DAYIndicates day tank fuel supply is running low.WarningCheck fuel supply and replenish as required.
241LOW FUELLow fuel signal received.WarningCheck fuel supply and replenish; check for short to ground in external wiring.
250EEPROM ERRORPCC memory error; data corruption of critical operating parameters.ShutdownPerform the initial start setup procedure; if the set shuts down on the same EEPROM ERROR message, replace the digital board (A32).
251EEPROM ERRORPCC memory error; data corruption of noncritical operating parameters.WarningPerform the adjustment procedures; if the same message occurs, perform calibration procedures; if the message persists, replace the digital board (A32).
252EEPROM ERRORPCC memory error; data corruption of noncritical operating parameters.WarningVerify values/choices selected and repeat the save operation; if the same message occurs, replace the digital board (A32).
260CUSTOMER FAULT 1When this customer defined input is closed to ground, the corresponding fault message is displayed. Programmable to initiate a shutdown or a warning.WarningIsolate source of false signal; repair external wiring or replace A34.
261GROUND FAULTWhen a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.WarningIsolate source of false signal; repair external wiring or replace A34.
262RUPTURE BASINWhen a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.WarningIsolate source of false signal; repair external wiring or replace A34.
263HIGH GEN TEMPWhen a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.WarningIsolate source of false signal; repair external wiring or replace A34.
270PHASE ROTATIONThe phase relationship between the generator set and the system bus is not matched.ShutdownVerify genset phase rotation matches bus; verify control wiring to bus PT module.
272FIRST STARTPowerCommand control is not receiving a proper signal from the system master first start sensor.WarningVerify Master First Start Sensor and interconnection wiring.
301HIGH AC VOLTAGEOne or more phase voltages exceeded 130% of nominal, or exceeded 110% of nominal for 10 seconds.ShutdownSet display to GEN, VOLTS, L-N; determine if the output voltage the control sees is low or high; isolate PCC/alternator/excitation circuit.
303LOW AC VOLTAGEOne or more phase voltages dropped below 85% of nominal for 10 seconds.ShutdownCheck PMG/field wiring, rotating rectifier, load and connectors.
313UNDER FREQUENCYIndicates that engine speed has dropped below 90% of nominal for 10 seconds. Five seconds before shutdown, a Load Dump signal is initiated.ShutdownCheck fuel supply, intake air supply and load.
320OVERCURRENTIndicates that generator output current has exceeded 110% of rated for 60 seconds.WarningCheck load and load lead connections.
321OVERCURRENTIndicates that generator output current has exceeded 110% of rated, and that a PCC time/current calculation has initiated an overcurrent shutdown.ShutdownCheck load and load lead connections.
322SHORT CIRCUITIndicates that generator output current has exceeded 175% of rated.ShutdownCheck load and load lead connections.
330OVERLOADThree-phase power output exceeds 105% of standby (or 115% of prime) rating.WarningCheck load and load lead connections.
335REVERSE POWERPower is flowing into the generator set rather than out from the unit.ShutdownVerify CT connections, load sharing lines, and generator set frequency/voltage.
337LOSS OF EXCITATIONAlternator excitation system is improperly adjusted or has failed.ShutdownCheck output voltage calibration, load sharing lines, and leading power factor loads.
FAULT 1Fault 1 (Red)Engine shut down because of a customer-connected system fault; part of a 10 second time delay shutdown circuit.ShutdownService as required by the customer-supplied fault indicating switches.
FAULT 2Fault 2 (Red)Engine shut down because of a customer-connected system fault; part of a non-time delay shutdown circuit.ShutdownService as required by the customer-supplied fault indicating switches.
GFGround Fault Alarm (Optional)Ground fault relay monitors neutral to ground connection and line to neutral, activating a fault alarm when the connection is broken or a ground fault is sensed.WarningClear fault condition by pushing the Run/Stop (Reset)/Remote switch to Reset (auto reset link set at factory).
HETHigh Engine Temperature (Red)Engine shut down because of excessively high engine coolant temperature (greater than 230 deg F).ShutdownCheck coolant level and leaks; service cooling system; reset engine control.
LETLow Engine Temperature (Yellow)Engine temperature is less than 70 deg F and the engine might not start.WarningPlug in, repair or install engine coolant and oil heaters.
LOPLow Oil Pressure (Red)Engine shut down because of excessively low engine oil pressure (less than 14 psi).ShutdownCheck oil level and oil leaks; service lubricating system; reset engine control.
LOW FUELLow Fuel (Yellow)Fuel level in the supply tank has dropped below the reserve necessary to run the set at full load for the prescribed number of hours.WarningFill the main fuel supply tank with the appropriate grade of fuel.
OCOvercrank (Red)Engine shut down because it did not start during the timed cranking period (approximately 75 seconds, including two rest periods).ShutdownService the set as necessary; reset engine control.
OSOverspeed (Red)Engine shut down because of overspeed.ShutdownAdjust the Electronic Overspeed Module; check governor for binding; reset engine control.
PRE-HETPre High Engine Temperature (Yellow)Engine coolant temperature is abnormally high (greater than 220 deg F).WarningShut down if possible or disconnect non-critical loads; service cooling system.
PRE-LOPPre Low Oil Pressure (Yellow)Engine oil pressure is abnormally low (less than 20 psi).WarningShut down if possible or disconnect non-critical loads; service lubricating system.
RUNRun (Green)Generator set is running and the starter has been disconnected.Info
SWITCH OFFSwitch-off (Flashing Red)The Run/Stop/Remote switch is in the Stop position, preventing remote automatic operation.InfoPush the Run-Stop-Remote switch to Remote.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

12
Aligning Generator with Engine (Angular Alignment) adjustment

⚠ Accidental starting of the generator set during this procedure presents the hazard of severe personal injury or death.

Tools: Dial indicator, Shims

  1. Disconnect the negative (-) battery cable(s) before beginning.
  2. Fasten a dial indicator to the generator shaft or cooling fan with the sensing point on the capscrew head or flat surface of the drive disc at the bolt circle diameter.
  3. Bar the engine over in a clockwise rotation as viewed from engine flywheel; do not allow it to roll back on compression.
  4. Determine the total indicator reading (T.I.R.) as the sum of the maximum positive and negative dial indicator readings over one revolution.
  5. Measure the distance from the center of the generator shaft to the indicator measuring point.
  6. Measure the distance from the generator side of the flex discs to the center of the generator mounting bolt.
  7. Compare the distances; multiply this ratio times one half the T.I.R. to approximate the amount of shims to remove or add.
Angular Alignment Procedure adjustment

⚠ Accidental starting of the generator set during this procedure presents the hazard of severe personal injury or death. Make sure to disconnect the negative (-) battery cable(s) before beginning.

Tools: Dial indicator, Wooden shims

  1. Disconnect the negative (-) battery cable(s) before beginning.
  2. Fasten a dial indicator to the generator shaft or cooling fan with sensing point on capscrew head or flat surface of drive disc at bolt circle diameter.
  3. Bar the engine over in a clockwise rotation as viewed from engine flywheel; do not allow it to roll back on compression.
  4. Record maximum positive and negative dial indicator readings as the engine completes one revolution.
  5. T.I.R. equals the sum of the maximum positive and negative readings.
  6. Maximum T.I.R. should not be more than .001 inch for each inch of radius.
  7. Remove equal shims from under both generator mounting feet to lower the generator.
Angular Alignment Procedure (Generator to Engine) adjustment

⚠ Accidental starting during this procedure presents the hazard of severe personal injury or death.

⚠ Do not bar engine over by prying on fan blade.

Tools: dial indicator

  1. Disconnect the negative (-) battery cable(s) before beginning.
  2. Fasten a dial indicator to the generator shaft or cooling fan with sensing point resting on the drive disc capscrew head/flat surface at the bolt circle diameter.
  3. Bar the engine over in a clockwise rotation as viewed from the engine flywheel; do not allow it to roll back on compression at the end of travel of each reading.
  4. Record the total indicator reading (T.I.R.) as the sum of the maximum positive and negative dial indicator readings over one engine revolution.
  5. Compare the measured T.I.R. to the maximum allowed (.001 in. per inch of radius from center of shaft to indicator axis); add or remove shims under the generator mounting feet to correct.
Axial Alignment Procedure (Generator to Engine) adjustment

Tools: dial indicator

  1. Fasten a dial indicator holding device to the skid base, engine block, or generator shell with the sensor point resting on the generator shaft hub.
  2. Bar the engine over in a clockwise rotation through a couple of rotations, recording indicator readings at eight equally spaced points around the shaft diameter to obtain axial T.I.R.
  3. Reduce the measured T.I.R. runout by one half if excessive vibration remains after angular alignment.
Governor Calibration Checks adjustment

Tools: Frequency meter or tachometer, Jumper wire

  1. Start the generator set.
  2. Adjust engine no-load speed to the desired allowable speed droop using the Run Speed potentiometer.
  3. With no load, turn GAIN clockwise slowly until engine speed oscillates.
  4. Reduce GAIN slowly counterclockwise until engine speed is stable.
  5. Upset the governor by momentarily shorting terminals 7 and 10 on the governor control.
  6. Apply and remove loads to check generator set response.
HC4-7 Axial Alignment Procedure adjustment

Tools: Dial indicator with magnetic base or clamp

  1. Check only when an objectionable vibration is present.
  2. Fasten dial indicator holding device to skid base, engine block, or generator shell with magnetic base or clamp.
  3. Position sensor point on the generator shaft hub.
  4. Bar the engine over in a clockwise rotation as viewed from engine flywheel through a couple of rotations.
  5. Record indicator readings in eight equally spaced points around the shaft diameter.
  6. Remove the capscrews connecting drive discs and flywheel and mark discs and flywheel.
  7. Rotate engine or generator so drive disc holes are repositioned 180 degrees from original location.
  8. Put capscrews back in and retorque. Recheck shaft alignment.
  9. If runout unchanged, rotate discs to 30, 60 or 90 degrees from original location.
  10. If T.I.R. does not improve, inspect flywheel pilot and drive disc runouts.
P7 Axial Alignment Procedure adjustment
  1. Check only when an objectionable vibration is present.
  2. Remove the capscrews connecting drive discs and flywheel.
  3. Mark the drive discs and flywheel with respect to each other.
  4. Rotate engine or generator so drive discs holes are repositioned two bolt holes from original location.
  5. Put capscrews back in and retorque. Recheck/record vibration levels.
  6. Repeat this test until drive disc holes are repositioned 180 degrees from original location.
  7. Review vibration data and position drive disc in lowest recorded level location.
UFRO Adjustments adjustment

⚠ Use an insulated handle screw driver to prevent electrical shock.

Tools: Insulated handle screwdriver, Frequency meter or tachometer

  1. Make a note of the no-load frequency.
  2. Determine roll-off frequency by turning the governor speed pot until the LED lights; if okay go to step 5.
  3. Adjust the governor speed pot to the proper roll-off frequency.
  4. Turn the UFRO pot until LED goes off, then slowly turn it back until the LED just goes on.
  5. Adjust the governor speed pot back to the initial frequency setting.
Voltage and Voltage Stability Adjustments adjustment

⚠ Touching uninsulated high voltage parts inside the control and power output boxes can result in severe personal injury or death.

Tools: Insulated handle screwdriver, AC voltmeter

  1. Use the control panel mounted voltage trimmer, if provided, for small voltage adjustments.
  2. Measure generator output voltage while running without load at nominal frequency.
  3. If trimmer is insufficient, lock it at midpoint.
  4. Turn the VOLTS pot fully counterclockwise and the STABILITY pot to its midpoint.
  5. If the red LED lights, refer to Jumper Reconnections and UFRO Adjustments.
  6. Turn the VOLTS pot clockwise until rated voltage is obtained.
  7. If voltage becomes unstable with a large load, turn the STABILITY pot clockwise until stable.
  8. Check and readjust the VOLTS pot each time the STABILITY pot is readjusted.
Generator/PCC Control Isolation Procedure diagnostic

⚠ HIGH VOLTAGE. Touching uninsulated high voltage parts inside the control box can result in severe personal injury or death.

Tools: Voltmeter, Jumpers, 12 volt battery

  1. Throw the line circuit breaker OFF and shut down the set.
  2. Remove accessory box cover; remove plug P10 from A37 J10.
  3. Prepare to measure output voltage across generator terminals.
  4. Connect 12V battery jumpers to X (P10-6 red) and XX (P10-3 brown).
  5. Check polarity; incorrect polarity makes the test inconclusive.
  6. Start set and connect battery negative to the XX lead.
  7. Rated or higher balanced voltage means generator circuitry is OK.
  8. Unbalanced voltage: troubleshoot main stator; low voltage: exciter/field.
Insulation Resistance (Megger) & Polarization Index (PI) Testing diagnostic

⚠ The windings of medium-voltage (601 through 15,000 volts) generator sets must be dry before the generator is operated.

Tools: Megger or insulation resistance meter, Grounding cluster, High voltage gloves

  1. Perform the Generator Set Grounding Procedure.
  2. Disconnect plug J10 from A37 and AC control leads 4,5,6,7,8.
  3. If RTD option installed, ground all six RTD temperature leads (18 leads).
  4. Perform Insulation Resistance Test and PI Test for desired windings.
  5. Megger test: apply voltage for up to one minute.
  6. PI test: apply voltage for ten minutes; record 1-minute and 10-minute readings.
  7. PI ratio of 2 or greater is good for new and in-service sets.
  8. Investigate and correct low readings before returning set to service.
Megger and PI Test diagnostic

⚠ Medium-voltage (601 to 15,000 volts) windings must be dry before the generator is operated.

Tools: Megger or Insulation Resistance Meter, Wheatstone bridge or digital ohmmeter, Grounding Cluster

  1. Perform the Generator Set Grounding Procedure.
  2. Disconnect plug J10 from the voltage regulator output module and the AC control leads (marked 4, 5, 6, 7, 8).
  3. If RTD option installed, ground all six RTD temperature leads (18 leads total).
  4. Perform the Winding Resistance Test for the desired windings.
  5. Perform the Insulation Resistance (Megger) Test and PI Test for the desired windings.
  6. Megger test: apply voltage for up to one minute.
  7. PI test: apply voltage for ten minutes; record resistance at one minute and ten minutes.
  8. PI is the ten-minute reading divided by the one-minute reading; ratio of two or greater is good.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Voltage reconnection

VoltagePhaseConnectionLeadsNotes
12 lead generator setsLoad wires are routed through the CTsReconnectable gensets (12 leads) have dual secondary CTs (3 pins); CT wire 2/3 to pin 2 (high voltage) or pin 3 (low voltage).
6 lead generator setsGenerator output leads are routed through the CTsNon-reconnectable gensets (6 leads) have single secondary CTs (2 pins).
Cummins PowerCommand generic AC Reconnect Wiring Diagram 625-2755 (Rev. D) and 625-3100 (Rev. F)Applies to models DFAA, DFAB, DFAC, DFBF, DFCB, DFCC, DFEB, DFEC, DFFB, DFGA, DFGB, DFJA, DFJB, DFJC, DFJD, DFLB, DFLC, DFLD, DFMB (625-2755) and models DFAA-DFMB plus DFCE, DFED, DQAA, DQAB, DQBA, DQBB (625-3100).
A (U)CT21U load leads (A phase)CT dot must face the generator; CT terminal 1 connects to metering circuit, terminal 2/3 to ground.
B (V)CT22V load leads (B phase)CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.
C (W)CT23W load leads (C phase)CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Common questions

What size generator is the Cummins/Onan DQAB?

The Cummins/Onan DQAB is rated 250 kW standby.

What engine does the Cummins/Onan DQAB use?

The Cummins/Onan DQAB is powered by the Cummins/Onan M11 engine.

Is the Cummins/Onan DQAB diesel or gas?

The Cummins/Onan DQAB runs on Diesel.

What is the oil capacity of the Cummins/Onan DQAB?

The Cummins/Onan M11 engine in the Cummins/Onan DQAB has an oil capacity of 34.0 liters.

What is the cooling system capacity of the Cummins/Onan DQAB?

The Cummins/Onan DQAB cooling system holds 49 liters (12.9 US gallons) for the radiator system including the engine, per the manufacturer specification sheet.

What is the continuous rating of the Cummins/Onan DQAB?

The Cummins/Onan DQAB is rated 225 kW prime, against 250 kW standby.

What is the sound level of the Cummins/Onan DQAB?

The Cummins/Onan DQAB is rated at 75.0 dBA at 7 m, per the manufacturer specification sheet.

What is the dry weight of the Cummins/Onan DQAB?

The Cummins/Onan DQAB has a dry weight of 5815 kg (12819 lb).

What size fuel tank does the Cummins/Onan DQAB have?

The Cummins/Onan DQAB has a 1040 liter (275 US gallon) fuel tank.

What voltage does the Cummins/Onan DQAB produce?

The Cummins/Onan DQAB is offered in 480/277 V, 208/120 V, 240/120 V, 3-phase.

How many cold cranking amps does the Cummins/Onan DQAB require?

The Cummins/Onan DQAB uses 2 batteryies, 24 V each, 1400 CCA, group 8D, per the manufacturer specification sheet.

Which alternator is fitted to the Cummins/Onan DQAB?

The Cummins/Onan DQAB uses a S-1140 alternator.

What air filter does the Cummins/Onan DQAB use?

The Cummins/Onan DQAB uses air filter part number 3666075.

Parts

45
Part #DescriptionQtySystem
0300-4623-05DFAA (600V)1Current transformer Amazon eBay
0300-4623-07DFAC (600V)1Current transformer Amazon eBay
0300-4623-17DFAA BR (0-480V)1Current transformer Amazon eBay $165.95
0300-4623-21DFAC BR (0-480V)1Current transformer Amazon eBay
256837Air Compressor Air Cleaner Element - Two-Cylinder, Sponge Element1Air filter Amazon eBay
3315843Fuel-Water Separator (Superfilter) (Fleetguard Part No. FS-1212)Fuel filter FridayParts $20.15
3318853Combination Full-Flow/Bypass Lubricating Oil Filter1Oil filter Amazon eBay $74.95 NAPA $66.59
DCA75LDCA4 Liquid, 18.9 l [5 U.S. gal], 200 SCA unitsFluid buy
LF670Full Flow lubricating oil filter1Oil filter Amazon eBay $35.95 KuduParts $74.00
LF777Lube, By-Pass Spin-On1Oil filter Amazon eBay $34.95 FridayParts $43.56
LT215/85R16/ETire Size/Load RangeTire buy
WF2050Fleetguard DCA (Fleetcool) Service Filter, 2 SCA unitsCoolant filter buy
WF2052Fleetguard DCA (Fleetcool) Service Filter, 6 SCA unitsCoolant filter buy
WF2053CoolantCoolant filter Amazon eBay $14.49
WF2054Coolant1Coolant filter Amazon eBay $17.99
WF2055Fleetguard DCA (Fleetcool) Service Filter, 23 SCA unitsCoolant filter buy
WF2070Coolant Filter6Coolant filter Amazon eBay
WF2071Coolant1Coolant filter Amazon eBay $18.95 NAPA $21.06 FridayParts $37.53
WF2072Coolant Filter1Coolant filter Amazon eBay $20.95 NAPA $29.33
WF2073Coolant Filter1Coolant filter Amazon eBay $14.40 NAPA $36.44
WF2074Coolant1Coolant filter Amazon eBay $24.00 NAPA $41.78 FridayParts $38.99
WF2076Coolant1Coolant filter Amazon eBay $32.94 FridayParts $18.99
WF2077Blank coolant filter without SCAsCoolant filter buy
98/37/ECNot specified in the documentService part / kit buy
CC2602Fleetguard coolant test kit50Service part / kit Amazon eBay
CC2800Fleetguard refractometerService part / kit Amazon eBay
EN29001Not specified in the documentService part / kit Amazon eBay
EN292Not specified in the documentService part / kit Amazon eBay
HP1300WCUNot specified in the documentService part / kit Amazon eBay FridayParts $72.68
HP825WCUNot specified in the documentService part / kit Amazon eBay FridayParts $85.99
HP935WCUNot specified in the documentService part / kit Amazon eBay FridayParts $29.69
PN8NTC2Not specified in the documentService part / kit Amazon eBay
VHP1050WCUNot specified in the documentService part / kit Amazon eBay
VHP750WCATNot specified in the documentService part / kit Amazon eBay
VHP825WCUNot specified in the documentService part / kit Amazon eBay FridayParts $89.80
VHP850WCATNot specified in the documentService part / kit Amazon eBay
XHP1070WCUNot specified in the documentService part / kit Amazon eBay
XHP1170WCUNot specified in the documentService part / kit Amazon eBay FridayParts $5800.99
XHP1300WCUNot specified in the documentService part / kit Amazon eBay
XHP650WCATNot specified in the documentService part / kit Amazon eBay FridayParts $408.99
XHP750WCATNot specified in the documentService part / kit Amazon eBay FridayParts $398.56
XHP825WCATNot specified in the documentService part / kit Amazon eBay
XHP900WCATNot specified in the documentService part / kit Amazon eBay FridayParts $59.99
XP1050WCUNot specified in the documentService part / kit Amazon eBay FridayParts $63.99
XP900WCUNot specified in the documentService part / kit Amazon eBay FridayParts $85.99

Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.

Available documents

Spec sheet — Cummins-installation-manual-DFAA-DFAB-DFAC-DFBC-DFBF-DFBD-DFBE-DFBF-DFCB-DFCC-DFCE-DFEB-DFEC-DFED-DFFA-DFFB-DFGA-DFGB-DFGC-DFJA-DFJB-DFJC-DFJD-DFLA-DFLB-DFLC-DFLD-DFLE-DFMB-DQAA-DQAB-DQBA-DQBB (Cummins/Onan)Spec sheet — s-1285 (Cummins/Onan)Parts manual — 960-0268 Onan DQAA DQAB DQBA DQBB Parts Manual (9-1991) (Cummins/Onan)Service manual — 960-0507C Cummins DFAA thru DFMB DQAA Service Manual (2-2004) (Cummins/Onan)Service manual — 960-0619D Cummins DFA DFB DFC DFE DFF DFG DFJ DFL DFM DQA DQB Installation (6-2003) (Cummins/Onan)Service manual — Cummins-3100-PowerCommand-DFAA-DFAB-DFAC-DFBC-DFBD-DFBE-DFBF-DFCB-DFCC-DFCE-DFEB-DFEC-DFED-DFFA-DFFB-DFGA-DFGB-DFGC-DFJA-DFJB-DFJC-DFJD-DFLA-DFLB-DFLC-DFLD-DFLE-DFMB-DQAA-DQAB-DQBB (Cummins/Onan)Service manual — DFxx Generator Set Service Manual PCC3100 (Cummins/Onan)Service manual — Detector Control Generator Set Service Manual (Cummins/Onan)

This page was generated from the 8 manufacturer documents above by automated extraction; every figure shown is copied from one of them. How the data is compiled.

Full service, cheapest listings

Priced items from this model's own parts manual.

Air filter 3666075$129.80
1 priced item$129.80
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