The output power of Cummins diesel generator sets decreases as altitude increases, due to reduced air density at higher elevations. This reduction affects combustion efficiency, turbocharger performance, and cooling effectiveness.

Here’s a technical breakdown of how altitude reduces power output in Cummins generators:

1. Reduced Air Density = Less Oxygen
Diesel engines require air (oxygen) to combust fuel.

At higher altitudes, the air is thinner (lower pressure and density), so less oxygen is available per intake stroke.

Result: The engine burns less fuel efficiently → reduced power output.

2. Derating of Power Output
Cummins applies derating factors above certain altitudes:

Typical Derating Guideline:
Above 1,000 meters (3,280 ft): Reduce power output by 3%–4% per 300 meters (1,000 ft) increase.

Example:

At 2,000 meters: Output is derated by ~6%–8%.

A 1,000 kVA genset might produce 920–940 kVA.

Actual derating values depend on the generator model, cooling system, and ambient temperature.

3. Turbocharger Performance
Turbocharged Cummins engines can compensate for altitude up to a certain limit, by forcing more air into the combustion chamber.

However, turbocharger performance also drops with air density beyond 2,500–3,000 meters, requiring additional derating.

4. Cooling System Impact
Thinner air at altitude also reduces cooling efficiency.

Cummins engines may overheat more easily unless the cooling system is adjusted.

This may require either:

A larger radiator or

A lower load to stay within thermal limits.

Cummins Official Resources:
Cummins provides derating charts and altitude guidelines in their generator set technical datasheets (Genset Data Sheets or G-Drive Technical Data). These should be consulted for project-specific applications.

How to Handle in Projects:
For projects above 1,000 meters, Cummins recommends applying altitude correction factors to ensure reliability. We select the right model and adjust the rated power.