Overview#
The MTU 12V0265 GS500 is a 500 kW natural gas standby generator set powered by the PSI 31.8L CAC — a 31.8-liter, 12-cylinder V-configuration turbocharged and charge-air-cooled spark-ignition engine producing up to 720 kWm gross on natural gas. This is one of the largest natural gas generator sets in the MTU Onsite Energy line and is designed for installations where utility natural gas eliminates the need for on-site diesel fuel management at commercial or light-industrial facilities.
On liquid propane vapor, the unit is rated at 350 kW standby — a 30% derating from the NG rating. The GS500 is also one of the few units in the MTU gas line available in 4,160V three-phase configuration (in addition to 208–600V), making it suitable for medium-voltage distribution applications in industrial plants.
The Bosch electronic isochronous governor delivers ±0.5% steady-state frequency regulation. The generator end uses Leroy-Somer LSA 49.1 and LS 50.2 series alternators — a departure from the MTU/Stamford alternators used in the diesel line. Standard equipment includes a 24V quad-battery electric start system (2,800 CCA total), unit-mounted radiator, and the MTU digital control panel with SAE J1939, NFPA 110 compatibility, and IP 54 protection. A separate intercooler water pump is standard to maintain charge-air cooling independent of the main jacket water circuit.
Technical Specifications#
Power Ratings (60 Hz, 1800 rpm)
| Rating | kW | kVA |
|---|---|---|
| Standby — NG | 500 | 625 |
| Standby — LP | 350 | 438 |
Engine — PSI 31.8L CAC
| Parameter | Value |
|---|---|
| Displacement | 31.8 L (1,941 in³) |
| Configuration | 12-cylinder V |
| Aspiration | Turbocharged and charge-air-cooled |
| Rated speed | 1800 rpm |
| Governor | Bosch electronic isochronous, ±0.5% |
| Max gross power (NG) | 720 kWm (966 bhp) |
| Max gross power (LP) | 475 kWm (637 bhp) |
| Emissions | EPA certified, 3-way catalyst |
| Starting | 24V, 4x 8D batteries, 2,800 CCA |
Fuel Consumption (natural gas at 1000 BTU/ft³)
| Load | NG Consumption | LP Consumption |
|---|---|---|
| 100% load | 6,072 ft³/hr (172 m³/hr) | 2,033 ft³/hr |
| 75% load | 4,972 ft³/hr (141 m³/hr) | 1,645 ft³/hr |
| 50% load | 3,823 ft³/hr (108 m³/hr) | 1,273 ft³/hr |
Physical (Open Power Unit)
| Dimension | Value |
|---|---|
| Length | 4,742 mm (186.8 in) |
| Width | 2,222 mm (87.5 in) |
| Height | 2,457 mm (96.8 in) |
| Dry weight | 8,500 kg (18,740 lb) |
Cooling System
| Parameter | Value |
|---|---|
| Radiator ambient rating | 50°C (122°F) |
| Water pump capacity | 1,368 L/min (361 gpm) |
| Heat rejection to coolant | 503 kW |
| Heat rejection to aftercooler | 53 kW |
Our Service Experience#
At 500 kW, the GS500 is a project-grade generator installation. The nearly 19,000-pound weight and 187-inch length demand structural engineering for the concrete pad and access planning for equipment delivery. The 31.8L V12 engine requires full shop-level tooling for major service events — valvetrain, turbocharger, and fuel system work on this engine is not field-serviceable with a service van.
The intercooler water pump (separate from the main jacket water pump) is a critical component unique to this engine platform. It maintains charge-air cooling independently, and a pump seal failure that goes undetected will allow charge-air temperatures to rise, reducing power and increasing knock risk. Monitor coolant levels in both circuits at each service interval.
Gas supply at 6,072 ft³/hr requires a 3-inch NPT inlet and utility service engineering — this exceeds what a standard commercial gas meter can deliver without dedicated service sizing. Engage a licensed gas engineer before finalizing site design.
Frequently Asked Questions#
What voltages are available on the GS500? The GS500 is available in standard commercial voltages (208V, 240V, 480V, 600V three-phase) and also in 4,160V medium-voltage, making it suitable for medium-voltage distribution applications in industrial plants and large commercial facilities.
What is the LP standby rating? On LP vapor, the GS500 delivers 350 kW standby — a 30% reduction from the 500 kW NG rating. Size based on your primary fuel type.
How many batteries does the GS500 require? Four 8D group-size batteries in a 24V configuration providing 2,800 total cold cranking amps. All four batteries must be load-tested at each service interval; battery replacement should be done in sets.
What is the gas supply requirement? 3-inch NPT inlet connection; 178–279 mm H₂O (7–11 in. water column) supply pressure; 6,072 ft³/hr at full load. This requires utility service engineering and a dedicated generator gas service line.
