Service parts for the C250
Grouped by system, with how many of each the parts manual calls for.
Fuel system
1 requiredPrices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.
Specifications
| Fuel | Natural gas |
|---|---|
| Frequency | 60.0 Hz |
| Standby power | 250 kW |
| Standby kVA | 312 |
| Controller | PowerCommand 3.3 |
| Oil capacity | 34.0 L |
| Alternator | S4L1D-D41 (4-pole, Class Class H insulation) |
Engine
| Oil capacity | 34.0 L |
|---|---|
| Coolant capacity | 136.0 L |
| Displacement | 14.0 L |
| Aspiration | Turbocharged and coolant-air aftercooled |
| Rated speed | 1800 rpm |
Maintenance & consumables
for the Cummins/Onan GTA855E| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | — | ||||
| Fuel filter | 149-0751 | Amazon eBay | |||
| Oil filter | — | ||||
| Battery | — | ||||
| Belt | — | ||||
| Coolant | 136.0 | — | |||
| Oil | 34.0 | — | |||
| Spark plug | — |
Service specifications
29| Type | Item | Value | Unit | Condition |
|---|---|---|---|---|
| Other | BMEP at set rated load | 243 | psi | |
| Other | Battery charging alternator | 37 | amps | |
| Other | Compression ratio | 8.5:1 | ||
| Other | Cranking current | 880 | amps | at ambient temp of 0 °C (32 °F) |
| Other | Frequency regulation | Isochronous | ||
| Other | Maximum speed | 2250 | rpm | |
| Other | Piston speed | 1795 | ft./min | |
| Other | Random frequency variation | ±0.5 | % | |
| Other | Regenerative power | 33 | kW | |
| Pressure | Catalyst back pressure | 20.4 | in. H2O | |
| Pressure | Fuel inlet pressure at GenSet connection | 356 to 508 | mm WC (14 to 20 in. WC) | |
| Pressure | Fuel inlet pressure maximum operating | 20 | in. H2O | |
| Pressure | Fuel inlet pressure minimum operating | 14 | in. H2O | |
| Pressure | Max air cleaner restriction (dirty filter) | 15 | in. H2O | |
| Pressure | Max allowable system back pressure | 47.7 | in. H2O | |
| Pressure | Max cooling air flow static restriction | 0.5 | in. H2O | |
| Pressure | Silencer back pressure (factory enclosed units only) | 5.6 | mm Hg (.22 in. Hg) | Factory enclosed units only |
| Pressure | Total system back pressure allowed | 51 | mm Hg (2 in. Hg) | |
| Resistance | Rotor resistance | 1.05 | Ohms | @ 22°C |
| Resistance | Stator resistance (L-L) | 0.0248 | Ohms | @ 22°C |
| Speed | Overspeed limit | 2100 | rpm | |
| Temperature | Ambient design | 104 | °F | |
| Temperature | Exhaust temp | 1146 | °F | |
| Temperature | Standard temperature rise (alternator) | 125 | °C | |
| Torque | Tightening torque (circuit breaker lug) | 442.54 | Lbf.In | AWG 3/0...500 kcmil |
| Voltage | Excitation current full load | 2.3 – 2.2 | Amps | full load |
| Voltage | Excitation current no load | 0.7 – 0.5 | Amps | no load |
| Voltage | Random voltage variation | ±1 | % | Three-phase only |
| Voltage | Voltage regulation, no load to full load | ±1 | % |
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 | 50/50 Mix | 136.0 L | System filled prior to shipment; Anti-Freeze 50/50 mix | ||
| Fuel | NG (natural gas) | Fuel inlet pressure at GenSet connection: 356 to 508 mm WC (14 to 20 in. WC) | |||
| Fuel | Natural gas | Fuel consumption at 100% load: 4098 SCFH; Required operating fuel pressure: 14-20 in H2O |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Procedures
2Switch Adjustment adjustment
Tools: wire seal MICROTUSEAL
- Open switch cover (A).
- Adjust the appropriate switches (B) to desired values.
- Replace switch cover. Use wire seal MICROTUSEAL (C), if necessary, to provide tamper evidence.
Trip Unit Operation Verification diagnostic
Tools: test kit
- Set pickup levels.
- Set time delay.
- Use a test kit connected to the trip unit test plug receptacle (A) to verify trip unit is functioning as desired.
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 |
|---|---|---|---|---|
| 208/416 | 3 | 12 | winding 311 | |
| 220/440 | 3 | 12 | winding 311 | |
| 230/460 | 3 | 12 | winding 311 | |
| 240 Delta | 3 | 12 | winding 311 | |
| 240/480 | 3 | 12 | winding 311 | |
| 277/480 | 3 | 12 | genset rated voltage, 3ph |
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 C250?
The Cummins/Onan C250 is rated 250 kW standby (312.0 kVA).
Which engine powers the Cummins/Onan C250?
The Cummins/Onan C250 is powered by the Cummins/Onan GTA855E engine.
What fuel type does the Cummins/Onan C250 take?
The Cummins/Onan C250 runs on Natural gas.
What is the oil capacity of the Cummins/Onan C250?
The Cummins/Onan GTA855E engine in the Cummins/Onan C250 has an oil capacity of 34.0 liters.
What is the cooling system capacity of the Cummins/Onan C250?
The Cummins/Onan C250 cooling system holds 136 liters (35.9 US gallons) for the engine, per the manufacturer specification sheet.
Which alternator is fitted to the Cummins/Onan C250?
The Cummins/Onan C250 uses a S4L1D-D41 alternator. It has 4 poles. Insulation class Class H.
Which fuel filter part number does the Cummins/Onan C250 take?
The Cummins/Onan C250 uses fuel filter part number 149-0751.
Troubleshooting
5Symptoms & remedies
| Symptom | Remedy |
|---|---|
| Battle short mode | If enabled and the battle short switch is active, some shutdown faults will be bypassed. However, emergency stop shutdowns and other critical operations are not bypassed. |
| Derate | The Derate function reduces output power of the genset in response to a fault condition. In utility parallel mode, it actively reduces power by lowering the base load kW to the derated target kW. |
| Configurable alarm and status inputs | The control accepts up to four alarm or status inputs (configurable contact closed to ground or open) to indicate a configurable condition. The control is programmable for warning, derate, shutdown, shutdown with cooldown or status indication and for labeling the input. |
| Emergency stop | Annunciated whenever either emergency stop signal is received from an external switch. |
| General prime mover protection | Low and high battery voltage warning - Indicates status of the battery charging system (failure) by continuously monitoring battery voltage. Weak battery warning - The control system will test the battery each time the genset is signaled to start and indicate a warning if the battery indicates impending failure. Low coolant level warning – Can be set up to be a warning or |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Parts
8| Part # | Description | Qty | System | |
|---|---|---|---|---|
| 0307-3047 | Relay (24V) | Relay 24v | Amazon eBay | |
| 0332-3923-02 | Terminal Block | 3 | Terminal block | Amazon eBay |
| 0332-3925-02 | Jumper-Terminal | Jumper terminal | Amazon eBay | |
| 0332-3943-02 | Jumper-Terminal | Jumper terminal | Amazon eBay | |
| 0332-4036-02 | Terminal Block (Earth) | Terminal block | Amazon eBay | |
| 0249-0814 | Relay 2P Base | 1 | Service part / kit | Amazon eBay |
| 0332-3926 | Terminal Block (End Stop) | 2 | Service part / kit | Amazon eBay |
| 0332-3927-02 | Terminal Block (End Plate) | 1 | Service part / kit | Amazon eBay |
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
This page was generated from the 4 manufacturer documents above by automated extraction; every figure shown is copied from one of them. How the data is compiled.