Important generator specifications include the generator's power rating, voltage, fuel consumption, speed and emissions information. Knowing whether a generator is designed for continuous, standby or intermittent operation is also important. A generator that needs to run constantly requires more robust specifications than one designed for emergency use.
Generators have two different electrical ratings, values that describe the amount of power the machine generates. The minimum rating describes the lowest amount of power the machine can produce, while the maximum rating states the highest amount. Each rating refers to power generation at a specific voltage and is expressed in electrical kilowatts.
Generators do not have a single fuel consumption rating. The amount of fuel a generator uses depends on its current load, meaning the amount of power it is generating. Manufacturers often list a generator's fuel consumption in gallons per hour at full, three-quarter, one-half and one-quarter loads. The larger a generator is and the greater its current load, the more fuel it consumes.
Emissions information is important because the U.S. Environmental Protection Agency has different standards for generators in different applications. The minimum emissions standards for a mission critical generator in constant use are much more stringent than the requirements for a standby generator for emergency use only.