Overview#
The Cummins C250 N6 is a 250-kilowatt natural gas standby generator built on the GTA855E — a 14-liter (854 in³) turbocharged inline-6 industrial gaseous engine. Unlike the smaller N6 models that use the QSJ family, the C250 N6 uses a larger-displacement engine platform with replaceable wet cylinder liners and a higher fuel pressure requirement, reflecting its commercial-grade heritage.
The C250 N6 is rated at 250 kW (312 kVA) standby, listed to UL 2200, and certified to EPA SI NSPS Stationary Emergency standards. The PowerCommand 3.3 control supports full paralleling functionality — including Phase Lock Loop synchronization, isochronous kW/kVar load sharing, and extended paralleling for baseload or peak-shave operation — making the C250 N6 well suited for multi-unit arrays and facilities requiring N+1 redundancy on natural gas.
The generator accepts full rated load in a single step per NFPA 110 Type 10 (ten-second transfer) for Level 1 and Level 2 EPSSs.
Dimensions (L x W x H): 3,734 mm x 1,676 mm x 1,997 mm (147 x 66 x 79 in.). Weight: consult factory for configuration-specific weights.
Technical Specifications#
| Parameter | Value |
|---|---|
| Standby Rating | 250 kW (312 kVA) |
| Frequency | 60 Hz |
| Power Factor | 0.8 |
| Engine Model | GTA855E |
| Displacement | 14 L (854 in³) |
| Configuration | Inline-6, wet cylinder liners |
| Aspiration | Turbocharged |
| Rated Speed | 1800 rpm |
| Starting System | 24 VDC, dual 8D batteries, 900 CCA |
| Battery Charging Alternator | 43 amps |
| Control | PowerCommand 3.3 |
| Dimensions (L x W x H) | 3734 x 1676 x 1997 mm (147 x 66 x 79 in.) |
Natural gas fuel consumption (SCFH):
| Load | SCFH |
|---|---|
| 25% | 950 |
| 50% | 1,951 |
| 75% | 2,692 |
| 100% | 3,440 |
Fuel inlet pressure: 381 to 508 mm WC (15 to 20 in. WC) at the generator set connection.
Available voltage configurations (three-phase): 120/208V, 127/220V, 139/240V, 220/380V, 240/416V, 254/440V, 277/480V, 347/600V
Our Service Experience#
The C250 N6 handles demanding commercial standby loads where gaseous fuel is the preferred choice. The GTA855E's larger displacement and wet liner design make it robust for long-term service, but turbocharger health and air/fuel calibration are the primary maintenance focus at this power level. The higher fuel inlet pressure requirement (15-20 in. WC) means gas supply system sizing is more critical than for the smaller N6 units — underpressure conditions will cause performance degradation that may not be immediately obvious until full-load testing.
We include gas supply pressure validation under load, turbocharger inspection, spark plug replacement, and full load bank testing in every annual service on C250 N6 installations. The PowerCommand 3.3 control's InPower service tool compatibility allows detailed diagnostics and fault history review at every service visit.
Frequently Asked Questions#
What engine does the C250 N6 use? The Cummins GTA855E — a turbocharged 14-liter (854 in³) inline-6 spark-ignited engine with replaceable wet cylinder liners, 24V starting, and a 43-amp battery charging alternator. Overspeed limit is 2100 rpm.
What is the fuel consumption of the C250 N6 at full load on natural gas? At 100% standby load: 3,440 SCFH. At 75%: 2,692 SCFH. At 50%: 1,951 SCFH. At 25%: 950 SCFH. Fuel inlet pressure at the generator connection must be 381 to 508 mm WC (15 to 20 in. WC).
What control system does the C250 N6 use? The PowerCommand 3.3 — providing full three-phase sensing, AmpSentry protection, paralleling capability (Phase Lock Loop synchronizer, isochronous kW/kVar load sharing), PCCNet and Modbus interface, and InPower service tool compatibility.
Can C250 N6 units be paralleled? Yes. The PowerCommand 3.3 control supports parallel operation. Two paralleled C250 N6 units can deliver 500 kW, useful for facilities needing capacity beyond a single unit or requiring N+1 redundancy on natural gas.
What fuel supply pressure does the C250 N6 require? Fuel inlet pressure at the generator set connection: 381 to 508 mm WC (15 to 20 in. WC). This is higher than the smaller C60-C150 N6 range and must be verified with the site gas system before installation.
