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Cummins/Onan QST30G4 Engine

Name: Cummins/Onan QST30G4 Engine
Brand: Cummins/Onan

The Cummins/Onan QST30G4 is a 30.5 L 12-cylinder turbocharged and charge air-cooled engine rated at 1500 rpm, producing up to 880 kW. It powers generator sets from Cummins/Onan, including the 800DFHD, C1100 D5, DFHD and DFHD 50 Hz. It holds 154 L (40.7 gal) of oil and 141 L (37.2 gal) of coolant.

Also known as: Cummins QST30G4

30.5 L

Displacement

Cylinders

1500 rpm

Rated speed

880 kW

Gross power

On this pageSpecs Generator sets FAQ Service intervals Torque & specs Fluids Fault codes Procedures Wiring

Engine specifications

Oil capacity	154.0 L
Coolant capacity	141.0 L
Displacement	30.5 L
Cylinders	12
Aspiration	Turbocharged and charge air-cooled
Rated speed	1500 rpm
Gross power	880 kW

Generator sets powered by this engine

Cummins/Onan 800DFHD Cummins/Onan C1100 D5 Cummins/Onan DFHD Cummins/Onan DFHD 50 Hz Cummins/Onan QST30-G4

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

Common problems

Warning lamp lights. MESSAGE: WEAK BATTERY 232 − WARNING 232
Fix: Discharged or defective battery. See Warning message 230, LOW DC VOLTAGE.
Warning lamp lights. MESSAGE: LOW FUEL DAY 240 − WARNING 240
Fix: Check fuel supply and replenish as required.
Warning lamp lights. MESSAGE: LOW FUEL 241 − WARNING 241
Fix: Check fuel supply and replenish as required.
Warning lamp lights. MESSAGE: LOW DC VOLTAGE 230 − WARNING 230
Fix: A. Discharged or defective battery. Check the battery charger fuse. Recharge or replace the battery. b. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. c. Contact an authorized service center if none of the above.
Warning lamp lights. MESSAGE: HIGH DC VOLTAGE 231 − WARNING 231
Fix: Contact an authorized service center.
Warning lamp lights.
Fix: Indicates battery voltage is below 24 VDC. a. Discharged or defective battery. Check the battery charger fuse. Recharge or replace the battery. b. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. c. Contact an authorized service center if none of the above.
Shutdown lamp lights. MESSAGE: MAG PICKUP 220 − SHUTDOWN 220
Cause: Indicates mag pickup speed indication is not being sensed or does not match generator set output frequency.
Fix: A. Restart and check RPM on the digital display. b. Contact an authorized service center.
Shutdown lamp lights. MESSAGE: FAIL TO CRANK 221 − SHUTDOWN 221
Fix: A. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. b. Discharged or defective battery. Recharge or replace the battery. c. Contact an authorized service center for service of starter and starting system.
Shutdown lamp lights. MESSAGE: EEPROM ERROR 250 − SHUTDOWN 250
Fix: Indicates PCC memory error. Data corruption of critical operating parameters. Contact an authorized service center.
Shutdown lamp lights. Engine will not crank. MESSAGE: OVERCRANK 222 − SHUTDOWN 222
Fix: A. Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required. b. Check for dirty fuel filter and replace if necessary. c. Check for dirty or plugged air filter and replace if necessary. d. Reset the control and restart after correcting the problem. Contact an authorized service center if none of the above.
Shutdown lamp lights. Engine will not crank. MESSAGE: FAIL TO CRANK 221 − SHUTDOWN FAIL TO CRANK 221 - SHUTDOWN
Fix: A. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. b. Discharged or defective battery. Recharge or replace the battery. c. Contact an authorized service center for service of starter and starting system.
Shutdown lamp lights. Engine stops cranking. MESSAGE: OVERCRANK 222 − SHUTDOWN OVERCRANK 222
Fix: A. Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required. b. Check for dirty fuel filter and replace if necessary. c. Check for dirty or plugged air filter and replace if necessary. d. Reset the control and restart after correcting the problem. Contact an authorized service center if none of the above.
Shutdown lamp lights. Engine runs and then shuts down. MESSAGE: OVERSPEED 223 − SHUTDOWN 223
Fix: Contact an authorized service center.
Shutdown lamp lights.
Fix: Check coolant level and replenish if low. Look for possible coolant leakage points and repair if necessary.
Engine stops cranking.
Cause: Discharged or defective battery.
Fix: Recharge or replace the battery. Clean the battery cable terminals and tighten all connections. Check engine DC alternator. Replace engine DC alternator if normal batery charging voltage (12 to 14 VDC) is not obtained.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan QST30G4.

Service intervals

Item	Action	Hours	Months	Notes
Crankcase Oil and Filter	Change	250 hr	12 mo	Footnote X6: If genset is used for standby applications, change oil every 12 months or 250 hours, whichever comes first
Rupture basin leak detect switch	Test		12 mo	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

Type	Item	Value	Unit	Condition
Clearance	Actuator maximum range	0 - 21	mm
Clearance	Actuator position fault threshold	1.5	mm	more than commanded position
Clearance	Exhaust pipe clearance from combustible wall or partition	12	inches (305 mm)
Clearance	Fuel line minimum clearance from electrical wiring	1/2	inch (12.7 mm)
Clearance	Fuel line minimum clearance from hot exhaust parts	2	inch (51 mm)
Clearance	Fuel rack position range	0 - 21	mm
Clearance	Generator/engine angular alignment T.I.R. (max)	.001	inch per inch of radius (center of shaft to indicator axis)	dial indicator at bolt circle diameter
Clearance	Left/right actuator fault threshold (more than this from commanded position)	1.5	mm
Clearance	Vibration isolator base elevation difference (max)	0.25	inch (6 mm)	shimmed or grouted, flat and level surface
Clearance	Vibration isolator top plate clearance (nominal)	0.25	inch (6 mm)	level, genset installed
Gap	Fuel rack travel (rack test)	0 to 19	mm	rack test
Gap	Governor actuator position fault threshold	more than 1.5 from commanded position	mm (actuator range 0-21 mm)
Other	Battery electrolyte specific gravity (charge threshold)	1.215		charge battery if below this reading
Other	Battery electrolyte specific gravity (fully charged)	1.260		corrected to 80°F (27°C)
Other	Bearing grease quantity	81	ml
Other	Engine torque adjustment range	0% to +1%	duty cycle units	approximately 0% to +2% engine horsepower
Other	Generator insulation resistance (frame HC6)	5.0 - 1.0	MEG	500 VDC megger setting
Other	Generator insulation resistance (frame P7)	10.0 - 1.0	MEG	500 VDC megger setting
Other	Governor duty cycle range	25 - 93	%
Other	Polarization Index (PI) acceptance ratio	2 or greater	ratio (10 min megohms / 1 min megohms)	new and in-service sets
Other	Rack position test voltage (disconnect fuel pump)	1.3 ±.25 to 4.5 ±.25	VDC	racks moved to 0mm
Other	Rack test position range	0 to 19	mm
Other	Start delay adjustment range	0 to 300	seconds
Other	Start delay adjustment range (Auto mode remote start)	0 to 300	seconds
Other	Stop delay adjustment range	0 to 600	seconds
Other	Stop delay adjustment range (Auto mode remote stop)	0 to 600	seconds
Other	Torque adjustment range	0% to +1%	% duty cycle
Other	Voltage regulator PWM duty cycle range	0 - 60	%
Other	Wrist strap resistance	approximately 1	megohm
Pressure	Engine oil pressure - idle	20	psi	idle mode
Pressure	Engine oil pressure - idle mode shutdown limit	10	psi	idle mode
Pressure	Engine oil pressure - idle mode warning limit	15	psi	idle mode
Pressure	Engine oil pressure - normal	45-65	psi	run mode
Pressure	Engine oil pressure - run mode shutdown limit	35	psi	run mode
Pressure	Engine oil pressure - run mode warning limit	40	psi	run mode
Pressure	Idle oil pressure	20	psi (138 kPa)	idle
Pressure	Idle oil pressure shutdown limit	10	psi (69 kPa)	idle
Pressure	Idle oil pressure warning limit	15	psi (103 kPa)	idle
Pressure	Maximum allowable exhaust back pressure	27	in. H2O (6.7 kPa)
Pressure	Maximum allowable exhaust back pressure	41	in. H2O (10.2 kPa)
Pressure	Maximum compressed air pressure for cleaning air filter element	30	psi (207 kPa)	air cleaner element cleaning
Pressure	Maximum compressed air pressure for cleaning radiator	35	psi (242 kPa)	radiator cleaning
Pressure	Maximum fuel inlet pressure	10	PSI (69 kPa)
Pressure	Maximum fuel inlet restriction	4	in. Hg. (13.5 kPa)
Pressure	Maximum fuel return restriction	10	in. Hg. (33.8 kPa)
Pressure	Maximum fuel return restriction	20	in. Hg. (67.6 kPa)
Pressure	Normal oil pressure	45-65	psi (310-448 kPa)	normal operating
Pressure	Oil pressure idle - QST30 engine	20	psi (138 kPa)	idle
Pressure	Oil pressure normal - QST30 engine	45-65	psi (310-448 kPa)	normal
Pressure	Oil pressure shutdown limit	10	psi (69 kPa)	idle mode
Pressure	Oil pressure shutdown limit	35	psi (241 kPa)	run mode
Pressure	Oil pressure shutdown limit - idle mode	10	psi
Pressure	Oil pressure shutdown limit - run mode	35	psi
Pressure	Oil pressure warning limit	15	psi (103 kPa)	idle mode
Pressure	Oil pressure warning limit	40	psi (276 kPa)	run mode
Pressure	Oil pressure warning limit - idle mode	15	psi
Pressure	Oil pressure warning limit - run mode	40	psi
Resistance	Coolant temperature sender resistance	500 to 2k	ohms
Resistance	Exciter rotor winding resistance (frame 6H)	1.54	ohms	68°F (20°C) ±10%
Resistance	Exciter rotor winding resistance (frames 6G, 6H, 6J, 6K)	0.158	ohms	at 68 F (20 C) +10%

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

Fluid	Grade	Ambient	Capacity	Notes
Fuel	ASTM No. 2 diesel fuel			Cummins engines normally use ASTM No. 2 diesel fuel and will operate on alternate diesel fuels within the specifications shown in the Cummins engine Operation and Maintenance Manual. Never use galvanized or copper fuel lines, fittings or fuel tanks.
Grease	Kluber, type ASONIC GHY72		75.0 grams	P7 generator bearing re-lubrication grease; must be filled with same type used at manufacture and MUST NOT be mixed with any other type.
Grease	Lithium based grease, Mobilux No. 2 or Shell Alvania R3	-30°C to 120°C	2.74 oz (81 ml)	Generator end bearing lubrication; grease divided equally 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

Code	Name	Meaning	Severity	Action
101	IDLE MODE	Indicates 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.	Warning	When ground is removed from the input, the genset returns to normal speed and voltage.
102	EMERGENCY STOP	Local or remote Emergency Stop activated.	Shutdown	Turn switch clockwise to pop out (local); move Run/Off/Auto to Off; press Reset; select Run or Auto.
200	LOW OIL PRESSURE	Indicates engine oil pressure has dropped to an unacceptable level.	Warning	If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow the 201-SHUTDOWN procedure. To check oil pressure, access the Oil Pressure menu prior to clearing the fault.
201	LOW OIL PRESSURE	Indicates engine oil pressure has dropped below the shutdown trip point.	Shutdown	Check oil level, lines and filters; reset control and restart.
204	OIL PRES SENDER	Oil pressure sender out of working range.	Warning	Check that the oil pressure sender is properly connected.
210	LOW COOLANT TEMP	Warning occurs when engine coolant temperature is 70 F (21 C) or lower. May be indicated even though coolant heaters are operating when ambient temperature falls below 40 F (4 C).	Warning	Check for coolant heater not connected to power supply (blown fuse or disconnected cord); check for low coolant level and replenish; check for open heater element (check current draw).
211	HIGH COOLANT TEMP	Indicates the engine coolant temperature is getting close to the recommended maximum temperature limit: 215 F (102 C) standby or 207 F (97 C) prime.	Warning	Reduce load; check air inlets/outlets for obstructions.
212	HIGH COOLANT TEMP	Indicates engine has overheated (coolant temperature above the shutdown trip point: 223 F (106 C) standby or 215 F (102 C) prime).	Shutdown	Check for obstructions to cooling airflow. Check fan belt. Reset control and restart after correcting problem.
213	COOLANT SENDER	Resistance of coolant temperature sender out of range.	Warning	Contact an authorized service center.
214	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Warning	Check coolant level and replenish; look for leaks.
215	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point. LOW COOLANT LVL Shutdown will not occur if genset is in Idle mode (low coolant warning only).	Shutdown	Check coolant level and replenish. Look for leaks. Reset control and restart.
220	MAG PICKUP	Mag pickup speed indication not sensed or does not match genset output frequency.	Shutdown	Restart and check RPM. Check wires and MPU adjustment.
221	FAIL TO CRANK	Possible fault with control or starting system.	Shutdown	Check fuse F3 on the Engine Interface board. Clean the battery cable terminals and tighten all connections. Recharge or replace the battery.
222	OVERCRANK	Possible fuel system problem.	Shutdown	Check fuel supply, fuel filter and air filter.
223	OVERSPEED	Indicates engine has exceeded normal operating speed (115% ±1% of nominal). Engine runs and then shuts down.	Shutdown	Perform rack position fault/test; check governor output module A38 and digital board A32.
224	FAIL TO SYNCHRONIZE	The generator set has not synchronized to the system bus within the allowable time frame.		Check the governor system stability and adjust governing and synchronizer parameters as required. Check for fuel system problems which can cause engine instability. Synchronizing time can be improved by widening the synchronizing window and reducing the acceptance time delay.
226	FAIL TO CLOSE	Indicates that the paralleling breaker has been given a signal to close, but has not closed properly.		Verify that the charging mechanism of the paralleling breaker is functioning properly. Check the close signal to the breaker. Verify that the auxiliary contact signals from the breaker to the PowerCommand control are operational.
230	LOW DC VOLTAGE	Indicates battery voltage is below 10 VDC.	Warning	Recharge or replace the battery. Check the battery charger fuse. Clean and tighten or replace the battery cable terminals and cables. Check the engine DC alternator; replace if normal charging voltage is not obtained.
231	HIGH DC VOLTAGE	Indicates battery voltage exceeds 32 VDC.	Warning	Lower battery charger float level.
232	WEAK BATTERY	Indicates battery voltage drops below 60% of nominal for two seconds during starting.	Warning	See warning 230 Low DC Voltage; recharge or replace battery.
240	LOW FUEL-DAY	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish.
241	LOW FUEL	Indicates fuel supply is running low.	Warning	Check fuel supply and replenish.
250	EEPROM ERROR	PCC memory error; data corruption of critical operating parameters.	Shutdown	Perform the initial start setup procedure. If the set shuts down on the same EEPROM ERROR message, replace the digital board (A32).
251	EEPROM ERROR	PCC memory error; data corruption of non-critical operating parameters.	Warning	Perform the adjustment procedures, save the adjustments and reset the control. If the error persists perform the calibration procedures. If the error still persists replace the digital board (A32).
252	EEPROM ERROR	PCC memory error; data corruption of non-critical operating parameters.	Warning	Verify values/choices and repeat the save operation; reset; if persists replace A32.
260	RACK POSITION	One or both fuel racks not at commanded position.	Warning	Programmable to initiate a shutdown or a warning.
261	GROUND FAULT	Default message; editable for customer site requirements.	Warning	Programmable to initiate a shutdown or a warning.
262	RUPTURE BASIN / DAY TANK	Default message; editable for customer site requirements.	Warning	Same as customer fault.
263	HIGH GEN TEMP	Default message; editable for customer site requirements.	Warning	Same as customer fault.
270	PHASE ROTATION	The phase relationship between the generator set and the system bus is not matched.	Shutdown	Using a phase rotation checker, verify that the generator set phase rotation matches the phase orientation of the system bus. Verify that control wiring to the bus PT module on the PowerCommand control is properly connected.
272	FIRST START	The PowerCommand control is not receiving a proper signal from the system master first start sensor. The control reverts to a fallback mode in which breaker closure is automatically allowed if bus is de-energized.	Warning	Verify that the Master First Start Sensor is properly functioning (pulsing voltage present on the terminal). Verify the voltage pulse is present at the PowerCommand Control (terminal TB1-50) and repair interconnection wiring.
301	HIGH AC VOLTAGE	One or more phase voltages exceeded 130% of nominal, or 110% for 10 seconds.	Shutdown	Determine if the output voltage the control sees is low or high. Isolate to the alternator/control, regulator module (A37)/A31/A32, PT/CT module (A36), customer interface board (A34), analog board (A33) or the generator per Table 4-30.
303	LOW AC VOLTAGE	One or more phase voltages dropped below 85% of nominal for 10 seconds.	Shutdown	Contact an authorized service center.
313	UNDER FREQUENCY	Indicates that engine speed has dropped below 90% of nominal for 10 seconds. Five seconds before shutdown, a Load Dump signal is initiated.	Shutdown	Contact an authorized service center.
320	OVERCURRENT	Indicates that generator output current has exceeded 110% of rated for 60 seconds.	Warning	Contact an authorized service center.
321	OVERCURRENT	Indicates that generator output current has exceeded 110% of rated, and that a PCC time/current calculation has initiated an overcurrent shutdown.	Shutdown	Contact an authorized service center.
322	SHORT CIRCUIT	Indicates that generator output current has exceeded 175% of rated.	Shutdown	Contact an authorized service center.
330	OVERLOAD	Three-phase power output exceeds 105% of standby (or 115% of prime) rating.	Warning	Contact an authorized service center.
335	REVERSE POWER	Indicates that power is flowing into the generator set rather than out from the unit. Can be caused by engine failure, inability to carry load, or control or interconnection problems.	Shutdown	Verify proper CT orientation, wiring and connections; verify proper connection of load sharing lines; verify the generator set is operating at the correct frequency and voltage per Table 4-34.
337	LOSS OF EXCITATION	Indicates that the alternator excitation system is improperly adjusted or has failed. May also be caused by operation of filters and power factor correction capacitors presenting a leading power factor load.	Shutdown	Start the generator set in RUN mode and check/calibrate output voltage. Check load sharing lines for proper interconnections. See Section 6 Servicing the Generator, Exciter Rectifier and Exciter Rotor.
401	INVALID SETUP	Indicates the digital board is not properly calibrated for the generator set model (the model number corresponding to the cut resistor and the initial setup are not compatible). No initial setup data is saved.	Shutdown	Refer to Digital Board (A32) Calibration; correct resistor selection and initial setup.
402	INVALID CAL	Indicates that the control senses that more than one calibration resistor has been cut. No initial setup data is saved.	Shutdown	Refer to Digital Board (A32) Calibration; correct resistor selection.
blank	LOAD DEMAND	The PowerCommand control has received a signal to shut down from a remote device. This is a normal operation mode typically used in automatic control systems to minimize generator set operation hours and system fuel consumption.		When the load demand signal is removed, the generator set will automatically start, synchronize, and close to the system bus.

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

Procedures

Aligning Generator with Engine adjustment

⚠ Accidental starting during this procedure presents a hazard of severe personal injury or death; disconnect negative battery cable first

Tools: Dial indicator, Shims

Fasten a dial indicator to the generator shaft or cooling fan with the point on the capscrew head or drive disc flat.
Bar the engine over clockwise one revolution; record the total indicator reading (T.I.R.).
Measure distance from generator shaft center to indicator point and from flex discs to mounting bolt center.
Compute shim change: multiply distance ratio by one half the T.I.R.
Keep T.I.R. not more than .001 inch for each inch of radius.
If axial runout is excessive, rotate drive discs 180 degrees (or 30/60/90 degrees) and retorque.

Analog Meter Calibration adjustment

Select >> from Main Menu, proceed to A−C VOLTS ADJ TO menu.
Start generator set and allow to reach normal operating speed.
Calibrate analog Voltmeter to digitally displayed value.
Calibrate analog % Amps meter to digitally displayed value.
Calibrate analog % Load meter to digitally displayed value.
Calibrate analog Frequency meter to digitally displayed value.
SAVE, then EXIT.

Angular Alignment Procedure adjustment

⚠ Accidental starting during this procedure presents the hazard of severe personal injury or death; disconnect the negative (-) battery cable(s) first.

⚠ Do not bar engine over by prying on fan blade; this may damage the blade and cause sudden blade failure.

Tools: dial indicator, shims, wrenches

Disconnect the negative (-) battery cable(s) before beginning.
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 bolt circle diameter.
Bar the engine over clockwise as viewed from engine flywheel; do not allow it to roll back on compression at the end of travel.
Total indicator reading (T.I.R.) is the sum of maximum positive and negative readings over one revolution.
Compare distance from generator shaft center to indicator point with distance from flex discs to generator mounting bolt center to get a ratio.
Multiply the ratio by one half the T.I.R. to determine the amount of shims to add or remove under the mounting feet.

Axial Alignment Procedure adjustment

Tools: dial indicator, dial indicator holding device with magnetic base or clamp, capscrew tools, torque wrench

Check axial misalignment only when an objectionable vibration is present.
Fasten a dial indicator to skid base, engine block, or generator shell so the sensing point rests on the generator shaft hub.
Bar the engine over clockwise as viewed from engine flywheel through a couple of rotations.
Record indicator readings in eight equally spaced points around the shaft diameter to obtain a T.I.R. for axial shaft misalignment.
To correct out-of-tolerance T.I.R., remove the capscrews connecting drive discs and flywheel and mark the discs and flywheel relative to each other.
Rotate engine or generator so drive disc holes are repositioned 180 degrees from original location; reinstall and retorque capscrews.
If runout is unchanged, rotate discs to 30, 60 or 90 degrees from original location.
If T.I.R. does not improve, inspect the flywheel pilot and drive disc runouts more closely.

Digital Ammeter Display Calibration adjustment

Tools: calibrated ammeter

Select >> from Main Menu, proceed to AMPS L1 menu.
With generator set OFF, attach calibrated ammeter to L1.
Start generator set and allow to reach normal operating speed.
Load generator set to maximum rated kVA at rated voltage.
Calibrate AMPS L1 reading to agree with calibrated ammeter.
Repeat steps 17 through 20 for L2 and L3.
Select EXIT if no calibration; SAVE then EXIT if calibration made.

Digital Coolant Temperature Display Calibration adjustment

Tools: precision resistor (engine sensor calibration tool)

With generator set OFF, replace coolant temperature sender with precision resistor in calibration tool.
Select >> from Main Menu, proceed to COOLANT TEMP L menu.
Calibrate temperature reading to match calibration tool.
Repeat step 32 for COOLANT TEMP R if engine uses two sensors.
Select EXIT if no calibration; SAVE then EXIT if calibration made.

Digital Power Factor Display Calibration adjustment

Tools: power factor meter

Select >> from Main Menu, proceed to PF1 menu.
With generator set OFF, attach power factor meter to L1.
Start generator set and allow to reach normal operating speed.
Load generator set to maximum rated kVA at rated voltage.
Calibrate PF1 reading to agree with power factor meter.
Repeat steps 24 through 27 for L2 and L3.
Select EXIT if no calibration; SAVE then EXIT if calibration made.

Digital Voltage Display Calibration adjustment

Tools: calibrated frequency/voltmeter

Select >> from Main Menu, proceed to VOLTS L12 menu.
With generator set OFF, attach calibrated frequency/voltmeter to AC output L1 to L2.
Start generator set and allow to reach normal operating speed.
Calibrate VOLTS L12 reading to agree with calibrated voltmeter.
Shut generator set OFF.
Repeat steps 10 through 13 for L23 and L31.
Select EXIT if no calibration; SAVE then EXIT if calibration made.

Engine Torque Adjustment adjustment

⚠ Calibration and adjustment must be performed by technically qualified personnel only

Tools: Calibrated instruments

Select >> from the Main Menu to proceed to the Torque Adjust %DC menu.
Start the generator set and allow it to reach normal operating speed.
Load the generator set to maximum rated kVA at rated voltage.
Adjust the torque limit up or down to achieve proper frequency under maximum load.
Select SAVE to retain the adjustment.

Voltage and Frequency Adjustment adjustment

Tools: calibrated frequency/voltmeter

Attach calibrated frequency/voltmeter to AC output L1 to L2 with generator set OFF.
Select ADJUST from Main Menu to display VOLTAGE adjust menu.
Start generator set and allow to reach normal operating speed.
Adjust VOLTAGE so calibrated voltmeter reads desired voltage.
Select Frequency adjust menu.
Verify frequency on calibrated meter is desired frequency. Adjust if not.
Select EXIT if no adjustment; SAVE then EXIT if adjustment made.

Generator/PCC Control Isolation Procedure diagnostic

⚠ High voltage - unregulated excitation of the generator is involved

Tools: 12 volt battery, Jumper leads

Throw the line circuit breaker OFF and shut down the set.
Remove P10 from connector J10 of the voltage regulator output module (A37).
Connect a 12 V battery positive jumper to X pin (red wire P10-6) and negative jumper to XX pin (brown wire P10-3).
Check polarity again; incorrect polarity makes the test inconclusive.
Start the set and connect the battery negative jumper to the XX lead.
If rated or higher balanced voltage is obtained, generator is probably OK; troubleshoot PCC control circuitry.

Ground Fault Relay Test diagnostic

Verify that the N-G Fault Indicator on the GFR is not lit (lit indicates the bonding jumper circuit is open).
Move the control switch to the Run position.
Press the TEST switch on the ground fault relay.
Verify that the control panel warning message is displayed and the Fault Indicator (>I) on the GFR is lit.
Reset the control panel fault (this will also reset the ground fault relay).

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

Phase	Connection	Leads	Notes
	PT/CT board J9	Yellow: Gen. A In; Orange: Gen. B In; Red: Gen. C In; Brown: Gen. Common In; White: CT21 (+) In; Gray: CT21 (common) In; Grn/Ylw: CT22 (+) In; Black: CT22 (common) In; Purple: CT23 (+) In; Blue: CT23 (common) In
A	CT1	U load leads	Dot on CT must face alternator.
B	CT2	V load leads	Dot on CT must face alternator.
C	CT3	W load leads	Dot on CT must face alternator.

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 is the oil capacity of the Cummins/Onan QST30G4?

The Cummins/Onan QST30G4 engine has an oil capacity of 154.0 liters.

What is the displacement of the Cummins/Onan QST30G4?

The Cummins/Onan QST30G4 has a displacement of 30.5 liters with 12 cylinders.

Which generators use the Cummins/Onan QST30G4 engine?

The Cummins/Onan QST30G4 powers 5 generator set(s), including Cummins/Onan 800DFHD, Cummins/Onan C1100 D5, Cummins/Onan DFHD, Cummins/Onan DFHD 50 Hz, Cummins/Onan QST30-G4.

What is a common problem with the Cummins/Onan QST30G4 engine?

A commonly reported issue on generators using the Cummins/Onan QST30G4 is: Warning lamp lights. MESSAGE: WEAK BATTERY 232 − WARNING. Fix: Discharged or defective battery. See Warning message 230, LOW DC VOLTAGE..