Overview#
The Generac SG500 is a 500 kW standby (450 kW prime) demand response ready industrial natural gas generator set powered by Generac's 25.8L V12 turbocharged and aftercooled spark-ignited engine. Rated at 625 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, Modbus RTU/TCP/IP, and Ethernet communications.
Engine and alternator#
The Generac 25.8L (1,574 cubic inch) V12 turbocharged/aftercooled engine delivers 500 kW standby at 729 hp and 204 psi BMEP at 1,800 RPM. The engine has a 10.0:1 compression ratio, forged steel alloy crankshaft, 7 main bearings, solid lifters, cast iron cylinder heads, and cast steel alloy cylinder liners. The 24V DC electrical system uses dual 12V batteries. Crankcase capacity is 95 quarts (90 L) — one of the largest in the SG series. Standard operating fuel pressure is 11–14 inches of water column (with 7–11 in H2O optional). Coolant system capacity is 25 gallons.
The standard alternator is the Generac K0500124Y23, 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 SG500 delivers 500 kW standby / 450 kW prime (753 A / 677 A). No single-phase configuration is available on this model.
Natural gas consumption at standby/demand response ratings: 5,862 scfh at 100% load, 4,770 scfh at 75%, 3,624 scfh at 50%, and 2,550 scfh at 25% load.
Physical dimensions#
The open set measures 154.4 x 70.5 x 74.9 inches (3,922 x 1,791 x 1,902 mm), weighing 9,386 to 9,739 lbs. Weather protected enclosure: 207.4 x 70.9 x 80.0 inches. Level 1 sound attenuated: 247.5 x 71.0 x 80.0 inches. Level 2 sound attenuated: 207.4 x 70.9 x 114.1 inches. Level 3 sound attenuated (steel only): 232.0 x 76.9 x 129.2 inches.
Our service experience#
The SG500 is the largest displacement model in the SG series at 25.8L — a step up from the 21.9L SG400 in the same general footprint class. The 95-quart crankcase is a significant maintenance consideration; oil changes at 500-hour intervals require careful planning for a waste oil volume of nearly 24 gallons per service. Fuel supply design is critical at 5,862 scfh full-load demand — gas distribution sizing for this model requires careful pressure drop analysis. The standard 11–14 in H2O fuel pressure requirement (vs 7–11 in H2O for the 14.2L models) demands proper utility line sizing. For demand response applications, a pre-season engine test under full load is strongly recommended before the summer peak season.
