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Generator De-rating on hot days

Generator de-rating on hot days

We’ve just experienced our hottest summers day in 3 years in Melbourne, at 42.8 C. These extremes temperatures are harsh on us, our pets and livestock, gardens, and equipment including electrical appliances and generators. The utility power grid is stressed by these conditions too and we experience brownouts and blackouts during these time as well. This is why owning a generator designed and built for these tough conditions is essential.

However, you would be surprised how many generators are actually designed for lower temperatures and do not cope with the harsh Australian summer, which is exactly when you need them to be working at their peak. Some small turbine generators start to reduce their power output from just 20℃ and some European generators are limited to 40℃ ambient. 

As the air heats up it expands or its density reduces. Hotter air provides fewer oxygen molecules for burning in an engine or turbine, so the potential power is reduced for some generators. Hotter, less dense air also provides less cooling for parts that get hot and rely upon air cooling, so increasing ambient temperatures can be a big deal. 

Reduced generator performance

The density of air at sea level 15℃ is 1.255 kg/m3 according to ISA (International Standard Atmosphere) but on a hot day of 40℃, this is reduced to 1.127 kg/m3 (source, a 10.2% reduction in the mass of air available for cooling and combustion. Think about the impact of a 10% reduction off the top of your generator performance on a hot day, right when you need it most. 

CHP’s are often installed within plant and equipment rooms along with other equipment that produces heat. These rooms can run warmer than the ambient temperature and be a comfortable place to visit on a cold winters day but horrible during summer. A 40℃ ambient day can be 50℃ in a plant room or shed, even with ventilation. 

Inoplex CHP generators

The Inoplex CHP generators are designed to power through hot summer days and provide reliable power when you need it most. Our power electronics will run at full capacity until a very uncomfortable 50℃ as standard, with higher temperatures available upon request. We design the engine combustion and air delivery systems to also run efficiently up to 50℃. 

If you are considering a CHP generator, make sure you cover off the full range of operating temperatures and ensure you have the capacity for when you need it on those hot summer days.