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Cummins/Onan LTA10 Engine

Name: Cummins/Onan LTA10 Engine
Brand: Cummins/Onan

The Cummins/Onan LTA10 is an engine. It powers generator sets from AKSA and Cummins/Onan, including the AC250, AC275, 2100 Series and DFAA. It holds 36 L (9.5 gal) of oil and 49 L (12.9 gal) of coolant.

Also known as: Cummins LTA10

36.0 L

Oil capacity

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

Engine specifications

Oil capacity	36.0 L
Coolant capacity	49.0 L

Generator sets powered by this engine

Shared across brands: AKSA, Cummins/Onan

AKSA AC250AKSA AC275Cummins/Onan 2100 SeriesCummins/Onan DFAA Cummins/Onan DFAB Cummins/Onan DFAC

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

Common problems

Over Current 1471
Low Coolant Level 197
Weak Battery 1442
Under Frequency 1448
Too Long in Idle 2342
Speed/Hz Match 1469
Speed Signal Lost 121
Shutdown After Battle Short 1123
Short Circuit 1445
Remote Emergency Stop 1434
Pre-Low Oil Pressure Sensor 143
Pre-High Cool Temp 146
Power Down Failure 1417
Overspeed 234
Over Frequency 1449

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan LTA10.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter			—
Fuel filter			—
Oil filter			—	250 hr
Battery	Two 12V Group 8D batteries		—
Belt			—
Coolant		49.0 L	—
Oil		36.0 L	—
Spark plug			—

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service intervals

Item	Action	Hours	Months	Notes
Rupture basin leak detect switch	Test		12 mo	Some areas may require weekly inspections by safety code.

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	Float switch assembly float lift clearance below C-clip stop	1/8	inch (3 mm)	use a feeler gauge
Clearance	Generator-to-engine angular alignment (T.I.R.)	.001 in. per inch of radius (center of shaft to indicator axis), maximum	in	750 kW gensets and larger
Clearance	MPU sensor to gear tooth adjustment	back out one quarter turn	turn	after contacting gear tooth
Clearance	Vibration isolator base elevation difference	0.25	inch (6 mm)	all isolator bases within this elevation of each other
Clearance	Vibration isolator clearance between top plate and base	0.25	inch (6 mm)	nominal or greater
Clearance	Vibration isolator top plate to base clearance	0.25	inch (6 mm)	nominal, or greater
Gap	Angular alignment total indicator reading (T.I.R.)	0.001	inch per inch of radius	maximum
Gap	Float switch lift to test open	1/8	inch	below C-clip stop
Other	AVR Droop setting	5	% at full load, 0 PF
Other	AVR voltage regulation (load regulation)	approximately ±0.5	% RMS
Other	Angular alignment maximum T.I.R.	.001	inch per inch of radius	center of shaft to indicator axis
Other	Battery specific gravity (high ambient, above 95F/35C)	1.225		recommended to reduce electrolyte loss
Other	Battery specific gravity (recharge threshold)	below 1.260
Other	GOV GAIN default value for paralleling applications	70	%
Other	Over/Under Frequency Sensor Module - Over Hz Set, 50 Hz nominal	55	Hz	reset 53 Hz
Other	Over/Under Frequency Sensor Module - Over Hz Set, 60 Hz nominal	65	Hz	reset 63 Hz
Other	Over/Under Frequency Sensor Module - Under Hz Set, 50 Hz nominal	45	Hz	reset 47 Hz
Other	Over/Under Frequency Sensor Module - Under Hz Set, 60 Hz nominal	55	Hz	reset 57 Hz
Other	Over/Under Voltage Sensor Module time delay	typically 25 percent, approximately 2.5	seconds
Other	Overcrank cranking limit	75	seconds	three 15-second cranking cycles with two 15-second rest periods
Other	REG VHZ (underfrequency roll-off) adjustable range	1 through 50; normal range 7 through 21
Other	Start delay adjustment range	0 to 300	seconds
Other	Stop delay adjustment range	0 to 600	seconds
Other	Under Frequency Roll Off (UFRO) knee point, 50 Hz units	48 to 49	Hz
Other	Under Frequency Roll Off (UFRO) knee point, 60 Hz units	58 to 59	Hz
Pressure	Engine oil pressure - K19 normal	50-70	psi (345-482 kPa)	run mode
Pressure	Engine oil pressure - K38 normal	45-65	psi (310-448 kPa)	run mode
Pressure	Engine oil pressure - K50 normal	50-70	psi (345-482 kPa)	run mode
Pressure	Engine oil pressure - L10/M11 normal	30-50	psi (207-345 kPa)	run mode
Pressure	Engine oil pressure - NTA 855 normal	35-50	psi (241-345 kPa)	run mode
Pressure	Engine oil pressure - V28 normal	50-90	psi (345-620 kPa)	run mode
Pressure	Engine oil pressure shutdown limit - L10/M11	20	psi (138 kPa)	run mode value
Pressure	Engine oil pressure shutdown limit - L10/M11	8	psi (55 kPa)	idle mode value
Pressure	Engine oil pressure warning limit - L10/M11	12	psi (83 kPa)	idle mode value
Pressure	Engine oil pressure warning limit - L10/M11	25	psi (172 kPa)	run mode value
Pressure	K19 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	K19 engine normal oil pressure	50-70	psi (345-482 kPa)	normal run
Pressure	K19 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)
Pressure	K38 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	K38 engine normal oil pressure	45-65	psi (310-448 kPa)	normal run
Pressure	K38 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)
Pressure	K50 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	K50 engine normal oil pressure	50-70	psi (345-482 kPa)	normal run
Pressure	K50 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)
Pressure	L10/M11 engine idle oil pressure	15	psi (103 kPa)	idle
Pressure	L10/M11 engine normal oil pressure	30-50	psi (207-345 kPa)	normal run
Pressure	L10/M11 oil pressure shutdown limit	20	psi (138 kPa)	run mode value
Pressure	L10/M11 oil pressure shutdown limit	8	psi (55 kPa)	idle mode value
Pressure	L10/M11 oil pressure warning limit	12	psi (83 kPa)	idle mode value
Pressure	L10/M11 oil pressure warning limit	25	psi (172 kPa)	run mode value
Pressure	Low oil pressure shutdown	below 14	psi (97 kPa)	time delayed ~10 seconds following starter disconnect
Pressure	NTA 855 engine normal oil pressure	35-50	psi (241-345 kPa)	normal run
Pressure	NTA 855 oil pressure shutdown limit	25	psi (172 kPa)	run mode value
Pressure	NTA 855 oil pressure shutdown limit	8	psi (55 kPa)	idle mode value
Pressure	NTA 855 oil pressure warning limit	12	psi (83 kPa)	idle mode value
Pressure	NTA 855 oil pressure warning limit	30	psi (207 kPa)	run mode value
Pressure	Pre-low oil pressure warning	20 or less	psi (138 kPa)
Pressure	V28 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	V28 engine normal oil pressure	50-90	psi (345-620 kPa)	normal run
Pressure	V28 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)

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	Standard	Ambient	Capacity	Notes
Coolant	soft water / E.G. / DCA mixture				Cooling system to be filled with soft water/E.G./DCA mixture (on-site review checklist).
Coolant		NFPA 110	above 4°C		NFPA 110 recommends engine jacket water coolant heaters where minimum ambient is above 40°F (4°C); coolant maintained at minimum 90°F (32°C). Cooling system capacity with standard radiator: DFAB/DFAC 13 Gal (49 L); DFBF 13.5 Gal (51 L); DFCC 13.5 Gal (51 L); DFCE 15 Gal (57 L).
Fuel	ASTM No. 2 diesel	Cummins engine Operation and Maintenance Manual alternate diesel fuels			Cummins engines normally use ASTM No. 2 diesel fuel. Never use galvanized or copper fuel lines, fittings or fuel tanks.
Fuel	ASTM No. 2 diesel fuel	ASTM No. 2			Cummins engines normally use ASTM No. 2 diesel fuel; they 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.
Fuel	Diesel				Day tank fuel transfer pump maintains reservoir of diesel fuel in the day tank.
Grease	Lithium based		-30°C to 120°C	81.0 ml	Mobilux No. 2 or Shell Alvania R3; generator end bearing; temperature range -22 F to +248 F (-30 C to +120 C); grease divided between bearing, bearing cap cavity and cartridge cavity.
Grease	Lithium based grease, Mobilux No. 2 or Shell Alvania R3		-30°C to 120°C	2.74 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

Code	Name	Meaning	Severity	Action
101	IDLE MODE	Indicates 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.	Warning	Remove ground from engine idle input to return to normal speed and voltage.
102	EMERGENCY STOP	Indicates local or remote Emergency Stop.	Shutdown	Turn 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.
1123	SHUTDOWN AFTER BS	Shutdown fault occurred while Battle Short was enabled and then disabled.	Shutdown	Review Fault History and perform corrective action.
1124	DELAYED SHUTDOWN	Shutdown fault became active while Delayed Shutdown feature was enabled.	Warning	Review Fault History and perform corrective action.
1131	BATTLE SHORT ACTIVE	Control is in Battle Short mode.	Warning	None; used for genset operation during emergencies.
121	SPEED SIGNAL LOST	Mag pickup speed indication is not being sensed.	Shutdown	Restart and check RPM on the digital display.
1311, 1312, 1317, 1318	CUSTOMER INPUT #1 - #4	Optional customer-selected fault input is active.	Warning	Disconnect signal lead from TB1 and reset the control; check external wiring/active input selection.
1334	CRIT SCALER OR	Incorrect feature or calibration was entered into control.	Shutdown	Reload correct feature/calibration file.
1335	NONCRIT SCALER OR	Incorrect feature or calibration was entered into control.	Warning	Reload correct feature/calibration file.
135	OIL PRESSURE SENSOR H	Engine oil pressure sender signal is shorted high.	Warning	Check sender/connectors/wires; verify fault simulation not enabled; check 0.5 to 4.5 VDC at P7-13 (OP OUT) and P7-17 (OP COM).
141	OIL PRESSURE SENSOR L	Engine oil pressure sender signal is shorted low.	Warning	Check sender/connectors/wires; check for shorts/open circuits at P7-13, 17, 21.
1416	FAIL TO SHUTDOWN	Genset continues to run after shutdown command.	Warning	Check Battle Short feature setting.
1417	POWER DOWN ERROR	Controller cannot power down.	Warning	Check for possible battery drain.
143	PRE-LOW OIL PRES	Engine oil pressure has dropped to an unacceptable level.	Warning	If critical loads, wait until next shutdown period and follow code 415.
1433	EMERGENCY STOP	Local Emergency Stop.	Shutdown	Pull the button out; move switch to O; press Fault Acknowledge/Reset; select Manual or Auto.
1434	REMOTE E-STOP	Remote Emergency Stop.	Shutdown	See code 1433 to reset.
1435	LOW COOLANT TEMP	Engine jacket water coolant temperature falls below 70°F (21°C); Warning LED illuminated (provided to meet NFPA 110 requirements)	Warning	Check the coolant heaters for proper operation
1438	FAIL TO CRANK	Engine failed to crank after the PCC received a start signal.	Shutdown	Test for B+ at the starter; check fuse F3 (2 Amps); check K4 start pilot relay and starter circuitry; refer to code 121.
144	COOL SENSOR HIGH	Engine coolant temperature signal is shorted high.	Warning	Check sender/connectors/wires; check resistance between P7-30 (IH20) and P7-34 (IH20 COM).
1442	WEAK BATTERY	During cranking battery voltage at or below weak battery trip point.	Warning	See code 441 for corrective action.
1443	BATTERY FAILED	Dead battery - engine will not start.	Shutdown	See code 441 for corrective action.
1444	KW OVERLOAD	Generator output power exceeded 105% of genset rating.	Warning	Check load and load lead connections; check CTs.
1445	SHORT CIRCUIT	Generator output current has exceeded 175% of rated.	Shutdown	Check load and load lead connections.
1446	HIGH AC VOLTAGE	Phase voltage exceeded 130% of nominal, or 110% of nominal for 10 seconds.	Shutdown	Check fault simulation; clear fault and restart; refer to Generator/Base Board Isolation Procedure.
1447	LOW AC VOLTAGE	Phase voltages dropped below 85% of nominal for 10 seconds.	Shutdown	Check overload, output terminal connections, PMG/field wiring, rectifier diodes.
1448	UNDER FREQUENCY	Engine speed dropped below 90% of nominal for 10 seconds.	Shutdown	Check fuel supply, intake air supply and load; check P8 connections.
1449	OVER FREQUENCY	Frequency is 10% above base frequency for 20 seconds.	Warning	Check fuel or air delivery; check connections.
145	COOL SENSOR LOW	Engine coolant temperature signal is shorted low.	Warning	Check sender/connectors/wires; check for shorts at P7-30 and P7-34.
1452	GEN CB NOT CLOSE	Genset circuit breaker (S2) failed to close when PTC is enabled.	Warning	Refer to Section 5.
1453	GEN CB NOT OPEN	Genset circuit breaker (S2) failed to open when PTC is enabled.	Warning	Refer to Section 5.
1459	REVERSE POWER	Improper CT phasing.	Shutdown	Check wiring to voltage sense circuit; refer to CT Installation in Section 6.
146	PRE-HIGH COOL TMP	Engine has begun to overheat.	Warning	Reduce load; check air inlets/outlets; follow code 151 if engine can be stopped.
1461	LOSS OF FIELD	Loss of field (electric) due to reverse kVAR.	Shutdown	Check field circuit.
1466	MODEM FAILURE	Control cannot communicate with the modem.	Warning	Check for open, short to ground and loose connections to the modem.
1468	NETWORK ERROR	Momentary loss of communication from the LonWorks Network.	Warning	Refer to the LonWorks Network publications.
1469	SPEED/HZ MATCH	Measured speed and measured AC output frequency do not agree.	Shutdown	Check calibration file.
1471	OVER CURRENT	Generator output current exceeded 110% of rated for 60 seconds.	Warning	Check load and load lead connections.
1472	OVER CURRENT	Output current exceeded 110% of rated and time/current calculation initiated shutdown.	Shutdown	Check load and load lead connections.
151	HIGH COOLANT TEMP	Engine has overheated above the shutdown trip point.	Shutdown	Allow engine to cool; check coolant level; check airflow obstructions; check fan belt; check blower fan/remote radiator pumps; reset control and restart.
197	LOW COOLANT LEVEL	Engine coolant level has fallen below the warning trip point.	Warning	Check coolant level and replenish if low; reset control.
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 201-SHUTDOWN procedure. 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; replenish if low; reset control and restart.
204	OIL PRES SENDER	Indicates that the control has sensed that the engine oil pressure sender is out of its working range.	Warning	Check that the engine oil pressure sender is properly connected.
210	LOW COOLANT TEMP	Warning occurs when engine coolant temperature is 70°F (21°C) or lower.	Warning	Warning LED illuminates. Check the coolant heaters for proper operation; if operating properly, other precautions may be necessary to warm the engine before applying a load.
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) − primary.	Warning	Reduce load if possible; check air inlets and outlets and remove obstructions to airflow.
212	OIL TEMP SENSOR H	Indicates engine has overheated (coolant temperature above 215° F (102° C) − standby or 207° F (97° C) − primary).	Warning	Check sender/connectors/wires; check resistance between P7-22 (OIL TEMP) and P7-26 (OIL TEMP COM).
213	OIL TEMP SENSOR L	Resistance of the coolant temperature sender is out of range.	Warning	Check the resistance of the sender; should be 500 to 2k ohms.
214	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Warning	Check coolant level in radiator and coolant recovery bottle; replenish if low; look for leaks.
215	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Shutdown	Allow engine to cool; check coolant level and leakage points; reset control and restart.
220	MAG PICKUP	Mag pickup speed indication is not being sensed or does not match generator set output frequency.	Shutdown	Restart and check RPM; check PCC model setting; inspect and test MPU.
221	FAIL TO CRANK	Possible fault with control or starting system.	Shutdown	Check fuse F3 on the Engine Interface board. Check for poor battery cable connections; clean battery cable terminals and tighten. Recharge or replace a discharged or defective battery.
222	OVERCRANK	Possible fuel system problem.	Shutdown	Check for empty fuel tank, leaks, plugged fuel lines; replace dirty fuel or air filter; reset and restart.
223	OVERSPEED	Indicates engine has exceeded normal operating speed. (115% ±1% of nominal).	Shutdown	Check mechanical fuel linkage and actuator; check governor output module (A38) and digital board (A32).
224	FAIL TO SYNCHRONIZE	Generator set has not synchronized to the system bus within the allowable time frame.	Warning	Check governor system stability; adjust governing and synchronizer parameters; check fuel system.
226	FAIL TO CLOSE	Paralleling breaker has been given a signal to close, but has not closed properly.	Shutdown	Verify breaker charging mechanism; check close signal; verify auxiliary contact signals.
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 battery cable connections. Check engine DC alternator; replace if normal charging voltage is not obtained. Check float level if applicable.
231	HIGH DC VOLTAGE	Indicates battery voltage exceeds 32 VDC.	Warning	Lower battery charger float level if applicable; check engine DC alternator.
232	WEAK BATTERY	Indicates battery voltage drops below 60% of nominal for two seconds, during starting.	Warning	See LOW DC VOLTAGE 230.
2327	PTC FAULT	PTC module or communication link not working properly when PTC enabled.	Warning	Check blinking light on PTC module; check B+ TB3-3 to TB3-4; check PTC status voltage TB3-5 to TB3-6 (~0.2 VDC); repower control.
2329	LOW S1 FREQUENCY	Low utility (S1) frequency.	Warning	Check S1 AC inputs and wiring to PTC at TB5; check sensor set points.
2331	LOW S1 VOLTAGE	Low utility (S1) voltage.	Warning	Repower PCC 2100 control to clear; check S1 AC inputs at TB5; check S1 pickup/dropout set points.
2335	EXCITATION FAULT	Loss of all three voltage sense leads or failure in excitation circuit.	Shutdown	Check field wiring (X1 and X2) for shorts or opens.
2336	MEMORY ERROR	Control memory error; data corruption of critical operating parameters.	Shutdown	Try reloading calibration file.
2337	PWR TRAN DISABLED	PTC module available but PTC feature not enabled.	Warning	Use InPower to enable PTC feature; cycle power off for 5 seconds then repower.
2338	PWR TRAN FAILURE	PTC module trim enabled but control could not communicate with PTC module.	Warning	Check blinking light and B+ TB3-3 to TB3-4; check connections between TB2 and TB3; cycle power.
2339	PWR DOWN ENABLED	Power Down (sleep) function enabled but PTC module or network board is active.	Warning	None required.
234	OVERSPEED	Engine has exceeded normal operating speed.	Shutdown	Clear fault and restart genset; check fault threshold; monitor RPM; check electronic governor actuator.
2341	HIGH CONTROL TEMP	Control temperature above normal (158 F [70 C]) for time greater than set time.	Warning	Check genset room air flow.
2342	TOO LONG IN IDLE	Genset has been in Idle mode too long.	Warning	Exit idle mode.
235	LOW COOLANT LEVEL	Engine coolant level has fallen below the shutdown trip point.	Shutdown	Check coolant level and replenish; look for leaks; reset control and restart.
2358	HIGH S1 VOLTAGE	Utility (S1) voltage increased above the over-voltage threshold.	Warning	Measure S1 AC inputs at PTC module; check utility nominal voltage; check sensor set points.
2396	S1 CB NOT CLOSE	Utility contact (S1) failed to close with PTC enabled.	Warning	Refer to Section 5.
2397	S1 CB NOT OPEN	Utility contact (S1) failed to open with PTC enabled.	Warning	Refer to Section 5.
240	LOW FUEL−DAY	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish as required.
241	LOW FUEL	Low fuel signal received.	Warning	Check fuel supply and replenish; check for short to ground in external wiring.
250	EEPROM ERROR	PCC memory error; data corruption of critical operating parameters.	Shutdown	Perform initial start setup procedure; replace digital board (A32) if fault repeats.
251	EEPROM ERROR	PCC memory error; data corruption of noncritical operating parameters.	Warning	Perform adjustment and calibration procedures; replace digital board (A32) if fault repeats.
252	EEPROM ERROR	PCC memory error; data corruption of noncritical operating parameters.	Warning	Verify selected values; repeat save operation; replace digital board (A32) if fault repeats.
260	CUSTOMER FAULT 1	When a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.	Warning	Isolate source of false signal; repair external wiring or replace A34.
261	GROUND FAULT	When a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.	Warning	Isolate source of false signal; repair external wiring or replace A34.

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

Procedures

Adjust Start/Stop Delays (PCC Adjust Menu) adjustment

⚠ Electrostatic discharge will damage circuit boards. Always wear a grounding wrist strap when working inside control box.

Press the button next to ADJUST in the Main Menu; the VOLTAGE submenu appears.
Press the button next to >> to move through VOLTAGE and FREQUENCY to the START DELAY submenu.
Use the buttons next to the up and down symbols to set the start delay.
Press >> to move to the STOP DELAY submenu and set the stop delay.
Press >> to move to the IDLE SPEED submenu and set idle speed (only in idle mode).
Press >> to move to SAVE/EXIT; select SAVE then EXIT to return to Main menu.

Adjusting Values/Parameters (PCC Adjust Menu) adjustment

Press the button next to the arrow symbol in the display until the + and - symbols are displayed.
If necessary, press the button next to the arrows to move to the numeric character to change.
Press + to increase the value or select the parameter; press - to decrease the value or select the parameter.
Press the save symbol to save changes; changes are not saved if Home or Previous Main Menu is pressed first.

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

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 the bolt circle diameter.
Bar the engine over in a clockwise rotation as viewed from engine flywheel; do not allow it to roll back on compression.
Determine the total indicator reading (T.I.R.) as the sum of the maximum positive and negative dial indicator readings over one revolution.
Measure the distance from the center of the generator shaft to the indicator measuring point.
Measure the distance from the generator side of the flex discs to the center of the generator mounting bolt.
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 (750 kW Gensets and Larger) 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.

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

Tools: Dial indicator, Shims

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 drive disc flat surface at bolt circle diameter.
Bar the engine over clockwise as viewed from the engine flywheel; do not allow it to roll back on compression.
Total indicator reading (T.I.R.) is the sum of the maximum positive and negative readings as the engine completes one revolution.
To lower the generator, remove equal shims from under both generator mounting feet; approximate shim amount from the distance ratio.

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

Disconnect the negative (-) battery cable(s) before beginning.
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.
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.
Record the total indicator reading (T.I.R.) as the sum of the maximum positive and negative dial indicator readings over one engine revolution.
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 adjustment

Tools: Dial indicator, Magnetic base or clamp

Check axial alignment only when an objectionable vibration is present after angular alignment.
Fasten dial indicator holding device to skid base, engine block, or generator shell with a magnetic base or clamp; rest sensor on generator shaft hub.
Bar the engine over clockwise through a couple of rotations; record indicator readings at eight equally spaced points around the shaft diameter.
To correct out-of-tolerance T.I.R., remove the drive disc capscrews, mark discs and flywheel, rotate 180 degrees from original location, retorque, and recheck.
If unchanged, rotate the discs to 30, 60 or 90 degrees from their original location.

Axial Alignment Procedure (Generator to Engine) adjustment

Tools: dial indicator

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.
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.
Reduce the measured T.I.R. runout by one half if excessive vibration remains after angular alignment.

Generator/Base Board Isolation Procedure diagnostic

⚠ This test involves unregulated excitation; disconnect all loads.

⚠ HAZARDOUS VOLTAGE.

Tools: Voltmeter, 12 volt battery, Jumpers

Throw line circuit breaker OFF and shut down the set.
Remove control housing side cover; disconnect exciter stator X and XX leads from AC harness.
Prepare to measure output voltage across generator terminals while set runs.
Connect a 12V battery jumper positive (+) to X lead (Field +).
Check polarity again; polarity must be correct.
Start the set and connect battery negative (-) jumper to XX lead.
If rated output voltage or higher and all phases balanced, generator is likely OK.
If unbalanced troubleshoot main stator; if uniformly low troubleshoot exciter and field circuits.

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

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

Ground Fault Relay Test diagnostic

Verify that the N-G Fault Indicator on the GFR is not lit; if lit, the neutral-to-ground 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, which also resets the ground fault relay.

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

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

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

Voltage	Phase	Connection	Leads	Notes
		12 lead generator sets	Load wires are routed through the CTs	Reconnectable 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 sets	Generator output leads are routed through the CTs	Non-reconnectable gensets (6 leads) have single secondary CTs (2 pins).
		CT1 - U load leads (A phase); CT2 - V load leads (B phase); CT3 - W load leads (C phase)	6 lead gensets: generator output leads routed through CTs; 12 lead gensets: load wires routed through CTs	12-lead sets have dual secondary CTs (3 pins); 6-lead sets 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).
		Current transformers CT21-U load leads (A phase), CT22-V load leads (B phase), CT23-W load leads (C phase)	CT secondary wire marked 1 to pin 1; wire marked 2/3 to pin 2 for high voltage gensets or pin 3 for low voltage gensets	CT dot must face toward the generator; CTs have dual secondaries (3 pins).
		Generator load terminals stamped U, V, W and N (U=L1, V=L2, W=L3, N=L0)	Stranded load wires bolted to generator reconnection terminal block or circuit breaker lugs	Available generator output voltages and maximum current ratings are specified on the generator set nameplate; line-to-neutral is the lower voltage, line-to-line the higher. Reconnection diagram is located on the upper side cover of the control housing.
	A (U)	CT21	U load leads (A phase)	CT dot must face the generator; CT terminal 1 connects to metering circuit, terminal 2/3 to ground.
	B (V)	CT22	V load leads (B phase)	CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.
	C (W)	CT23	W load leads (C phase)	CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.
110 V - 120 V L-N	1	Single phase, 2-wire		PTC module jumper locations
110V - 120V L-N	Single phase, 2-wire	Jumper locations for single phase, 2-wire		PTC Module AC wiring (0300-5382-01, -02)
190 V - 240 V L-L	3	Three phase		Use PTC module 0300-5382-01; 50/60 Hz
190, 200, 208, 220, 230, 240, 380, 416, 440, 460, 600 (L-L)	3 (three phase)	3 or 4 wires		Voltage Configuration submenu; default = 3Ph 208V 4W
190V - 240V L-L	Three phase	Jumper locations for three phase, 190V-240V L-L		Use 0300-5382-01 for 190V-240V L-L, 50/60 Hz
200 V - 240 V L-L	1	Single phase, 3-wire		PTC module jumper locations
200, 220, 230, 240 (L-L)	1 (single phase)	3 wires		Voltage Configuration submenu (Governor/Regulator Setup)
200V - 240V L-L	Single phase, 3-wire	Jumper locations for single phase, 3-wire		PTC Module AC wiring
380 V - 600 V L-L	3	Three phase		Use PTC module 0300-5382-02; 50/60 Hz
380V - 600V L-L	Three phase	Jumper locations for three phase, 380V-600V L-L		Use 0300-5382-02 for 380V-600V L-L, 50/60 Hz

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 LTA10?

The Cummins/Onan LTA10 engine has an oil capacity of 36.0 liters.

Which generators use the Cummins/Onan LTA10 engine?

The Cummins/Onan LTA10 powers 6 generator set(s), including AKSA AC250, AKSA AC275, Cummins/Onan 2100 Series, Cummins/Onan DFAA, Cummins/Onan DFAB.

What is a common problem with the Cummins/Onan LTA10 engine?

A commonly reported issue on generators using the Cummins/Onan LTA10 is: Over Current.