Overview#
The Generac SG250 is a 250 kW standby (225 kW prime) demand response ready industrial natural gas generator set powered by Generac's 14.2L inline-6 turbocharged and aftercooled spark-ignited engine at its highest output tuning in this displacement class. Rated at 313 kVA standby at 60 Hz, it is EPA certified for both stationary emergency and non-emergency applications. Available in three-phase configurations only, it features the Generac Power Zone Pro Sync controller with a 7-inch color touchscreen display.
Engine and alternator#
The Generac 14.2L inline-6 turbocharged/aftercooled engine achieves 250 kW standby at 1,800 RPM with a 9.5:1 compression ratio and 190 psi BMEP — the highest BMEP of the SG-series 14.2L models. Key construction features include a ductile iron crankshaft and cylinder liners, cast iron cylinder head, 7 main bearings, solid lifters, and high-temperature steel alloy exhaust valves with hardened valve seats. The 24V DC electrical system uses dual 12V batteries. Oil capacity is 36.2 quarts.
The standard alternator is the Generac K0250124Y21, a 4-pole revolving-field design with Class H insulation on both rotor and stator. It features permanent magnet excitation, full digital voltage regulation with plus or minus 0.25% steady-state accuracy, and total harmonic distortion below 5%.
Power ratings and fuel consumption#
At 277/480V three-phase and 0.8 power factor, the SG250 delivers 250 kW standby / 225 kW prime. No single-phase configuration is available on this model.
Natural gas consumption at standby/demand response ratings: 3,180 scfh at 100% load, 2,520 scfh at 75%, 1,620 scfh at 50%, and 1,020 scfh at 25% load.
Physical dimensions#
The open set measures 136.0 x 57.1 x 67.9 inches, weighing approximately 5,883 lbs — identical physical footprint and alternator to the SG230. Weather protected, Level 1, Level 2, and Level 3 sound attenuated enclosure options are available.
Our service experience#
The SG250 and SG230 are mechanically identical units differentiated only by output tuning. At 190 psi BMEP, the SG250 is the most aggressively tuned 14.2L model and runs at a slightly higher exhaust temperature (1,357 degrees F) than the SG230 (1,340 degrees F). For demand response applications logging significant annual hours, closer turbocharger inspection intervals are advisable. The shared alternator code (K0250124Y21) between SG230 and SG250 simplifies spare parts management when both models are installed at the same facility.
