Overview#
The Generac SD250 is a 250-kilowatt industrial diesel standby generator powered by an Iveco/FPT 8.7-liter turbocharged and aftercooled inline-six engine. Rated at 250 kW standby and 225 kW prime (313/281 kVA), the SD250 represents a major platform step-up from the 6.7L family: larger displacement, common rail injection, a 29.6-quart crankcase, and a 24-VDC electrical system with dual batteries. BMEP is 332 psi at the 250 kW standby rating, exhaust temperature is 1000°F (538°C), and heat rejection to coolant is 682,058 BTU/hr. The generator is EPA Certified for Stationary Emergency applications.
Generac pairs the Iveco 8.7L with the K0250124Y21 alternator featuring Class H insulation, Permanent Magnet excitation, and THD less than 5%. The Digital H control panel provides NFPA 110 Level I and II programmable operation, Modbus communications, and 16-channel remote trending. The 120 VAC coolant heater and closed coolant recovery system are standard equipment.
At 250 kW, this unit serves larger commercial and industrial standby applications: large multi-story office buildings, hospitals and healthcare campuses with life-safety loads, medium data centers, large industrial facilities with significant motor loads, and multi-building campus systems where a single larger generator is more efficient than multiple smaller units.
Technical Specifications#
| Parameter | Value |
|---|---|
| Standby Rating | 250 kW / 313 kVA |
| Prime Rating | 225 kW / 281 kVA |
| Engine Make | Iveco/FPT |
| Displacement | 8.7 L (530.9 in³) |
| Cylinders | 6, In-Line |
| Bore x Stroke | 4.61 x 5.31 in (117 x 135 mm) |
| Compression Ratio | 16.5:1 |
| Aspiration | Turbocharged/Aftercooled |
| Fuel Injection | Common Rail |
| Engine Speed | 1,800 RPM |
| Alternator Model | K0250124Y21 |
| Insulation Class | H |
| Fuel Type | Ultra Low Sulfur Diesel #2 |
| Fuel Consumption (100%) | 18.5 gph |
| Fuel Consumption (75%) | 14.8 gph |
| Fuel Consumption (50%) | 10.4 gph |
| Fuel Consumption (25%) | 5.5 gph |
| Exhaust Flow | 1,550 cfm at rated output |
| Exhaust Temperature | 1,000°F (538°C) |
| Heat Rejection to Coolant | 682,058 BTU/hr |
| Combustion Air | 720 cfm |
| Ventilation Air | 8,872 cfm |
| Open Set (no tank) L x W x H | 128.0 x 53.4 x 57.5 in |
| Open Set Dry Weight | 4,325 -- 5,108 lbs |
| Max Radiator Air Temperature | 122°F (50°C) |
Our Service Experience#
The SD250's common rail fuel injection system operates at much higher pressures than the mechanical or basic electronic injection found in smaller models. Common rail injection is highly sensitive to fuel contamination, water, and microbial growth -- fuel polishing and biocide treatment is not optional for this unit. We recommend quarterly fuel sampling and annual polishing for all SD250 installations.
The 24 VDC electrical system uses two 12V batteries in series. Inspect both batteries at every annual service; a weak battery in a series pair creates uneven discharge and failure at startup. The 1000°F exhaust temperature demands high-temperature-rated flex connectors and confirmed clearances from combustibles. At 18.5 gph full load, a 589-gallon sub-base tank provides approximately 31 hours of runtime -- the 946 to 1325-gallon options are often required for NFPA 110 Class 48 or Class 72 specifications.
Frequently Asked Questions#
How does the SD250 compare to the SD275? The SD250 uses the Iveco/FPT 8.7L inline-6 while the SD275 uses the 10.3L. The SD275 provides 10% more standby capacity (275 vs 250 kW), uses a larger engine with more exhaust flow (2050 vs 1550 cfm), and weighs significantly more (6121 lbs vs 4325 lbs open set). If 250 kW is sufficient, the SD250 is the more compact and lighter choice. If load growth to 275 kW is anticipated, specify the SD275 initially.
Is IBC seismic certification available for the SD250? Yes. IBC seismic certification is an engineered factory option for the SD250. Required for California hospitals, essential facilities, and all structures subject to CBC/IBC seismic requirements at the generator location.
What fuel tank options are available for the SD250? Sub-base UL 142 double-wall tanks are available in 153, 372, 500, 589, 693, 946, 1000, and 1325-gallon usable configurations. The larger tank options require extended footprint configurations. At 18.5 gph full load, the 1325-gallon tank provides approximately 71 hours of runtime -- meeting most NFPA 110 Class 72 requirements.
