Overview#
The Cummins C300 N6 is a 300 kW (375 kVA) standby natural gas generator set built on the GTA 855E -- a 14-liter, inline-6-cylinder, turbocharged spark-ignited engine producing 470 bhp (351 kWm). This is the largest inline-6 platform in the Cummins N6 gas generator series, filling the 250-350 kW class before the series steps up to V12 architecture. The 855-cubic-inch displacement engine has a long service history in stationary power applications and carries a major overhaul interval of 30,000 hours.
The C300 N6 operates at 1800 rpm with a 24-volt starting system requiring a minimum of 900 CCA cranking current. The alternator is an S4L1D-D41 (ADS #627) brushless, 4-pole, 2/3 pitch revolving field design with PMG excitation and Class H insulation. The control system is PowerCommand 3.3 MLD, providing isochronous governing, digital voltage regulation, AmpSentry protective relay functions, PCCNet communications, and NFPA 110 Level 1 compliance capability. A Schneider Electric PowerPact P-frame circuit breaker (LSi frame, 600A 100%, rated 600/525V) is included as standard equipment on this configuration.
The C300 N6 is certified by EPA for both stationary emergency (40 CFR 60) and stationary non-emergency applications, expanding its deployment flexibility beyond pure standby duty. The wet weight ranges from 8,066 to 8,527 lbs depending on configuration options.
Technical Specifications#
| Parameter | Value |
|---|---|
| Standby Rating | 300 kW (375 kVA) |
| Frequency | 60 Hz |
| Power Factor | 0.8 |
| Engine Model | GTA 855E (BOM: GTA855EICS) |
| Displacement | 855 in³ (14 L) |
| Configuration | Cast iron, in-line 6 cylinder |
| Aspiration | Turbocharged, spark-ignited |
| Bore x Stroke | 5.5 in x 6.0 in (140 mm x 152 mm) |
| Compression Ratio | 8.5:1 |
| Gross Engine Output | 470 bhp (351 kWm) |
| BMEP | 243 psi (1,675 kPa) |
| Piston Speed | 1,795 ft/min (9.1 m/s) |
| Rated Speed | 1800 rpm |
| Overspeed Limit | 2100 rpm |
| Lube Oil Capacity | 36 qt (34 L) |
| Starting System | 24V, negative ground |
| Minimum Cranking Current | 900 CCA |
| Battery Charging Alternator | 70 amps |
| Alternator Model | S4L1D-D41 (ADS #627) |
| Alternator Excitation | PMG |
| Alternator Insulation | Class H |
| Control | PowerCommand 3.3 MLD |
| Circuit Breaker | Schneider PowerPact P-frame, LSi 600A 100%, 600/525V |
| Dimensions (L x W x H) -- Open Set | 147 x 69 x 77 in (373 x 175 x 196 cm) |
| Wet Weight | 8,066 -- 8,527 lbs (3,659 -- 3,868 kg) |
Natural gas fuel consumption (CFH) -- Standby rating:
| Load | CFH |
|---|---|
| 25% | 1,387 |
| 50% | 2,201 |
| 75% | 3,104 |
| 100% | 4,098 |
Fuel inlet pressure: 14 to 20 in WC. Fuel inlet pressure must not exceed 25 in WC under any condition.
Our Service Experience#
The GTA 855E is a proven, long-service engine platform well-suited to the 300 kW standby role. The 36-quart oil capacity means oil changes are a significant maintenance event -- plan for proper oil collection and disposal infrastructure at the installation site. The 30,000-hour major overhaul interval is significantly longer than the 20,000-hour interval on the smaller QSJ5.9G and QSJ8.9G engines, which reflects the conservative displacement-to-power ratio of this larger-displacement turbocharged engine.
The 24V starting system with a minimum 900 CCA requirement should be verified annually with a battery load test -- both batteries must meet specification individually, since a degraded battery can mask a healthy one during routine testing. The PowerCommand 3.3 MLD control provides comprehensive protective relay functionality including AmpSentry, but requires the InPower service tool for threshold adjustment and fault history retrieval. Verify that fuel inlet pressure stays within the 14-20 in WC operating range under full load -- exceeding 25 in WC can cause equipment damage and must be treated as a hard limit during gas supply engineering.
Frequently Asked Questions#
What is the standby rating of the C300 N6? 300 kW (375 kVA) at 60 Hz, 0.8 power factor, per Emergency Standby Power (ESP) rating in accordance with NFPA 110. The unit is also EPA-certified for stationary non-emergency applications.
What engine does the C300 N6 use? The Cummins GTA 855E (BOM designation GTA855EICS) -- an 855 in³ (14-liter), in-line 6-cylinder, spark-ignited natural gas engine. Bore is 5.5 in (140 mm), stroke is 6.0 in (152 mm), compression ratio is 8.5:1, gross output is 470 bhp (351 kWm). Overspeed limit is 2100 rpm.
How much natural gas does the C300 N6 consume? At 100% standby load: 4,098 CFH. At 75%: 3,104 CFH. At 50%: 2,201 CFH. At 25%: 1,387 CFH. Fuel inlet pressure must be maintained between 14 and 20 in WC and must never exceed 25 in WC.
What control system does the C300 N6 use? PowerCommand 3.3 MLD, providing isochronous governing, digital voltage regulation, AmpSentry protective relay, PCCNet communications, auto start/stop, output metering, and NFPA 110 Level 1 compliance capability. InPower service tooling connects via RS-485 for diagnostics and configuration.
What does the C300 N6 weigh? Wet weight ranges from 8,066 to 8,527 lbs (3,659 to 3,868 kg) depending on configuration. Open set dimensions are 147 x 69 x 77 in (373 x 175 x 196 cm).
What voltages does the C300 N6 support? Three-phase configurations at 60 Hz: 120/208V, 127/220V, 139/240V, 220/380V, 240/416V, 254/440V, 277/480V, and 347/600V. The PMG-excited brushless alternator (S4L1D-D41, Class H) supports field voltage configuration across this range.
