What are the factors that may affect on Generator Rating ?

All electrical appliances have set conditions under which they function at optimum levels. Any fluctuations in these conditions can cause the appliances to run at a lower efficiency. Power generators are no exception to this.

 Generators are typically designed to run most efficiently at or near sea level under standard conditions of temperature and pressure (STP). Any fluctuation from STP conditions can impair generators and cause decreased output. 

Under extreme circumstances, generators can cease to function entirely.  For most applications, many of these factors are relatively minimal unless the generator set is run at elevations over 5000 feet above sea level, or has ambient temperatures that remain over 100 degrees Fahrenheit for a significant length of time. 

 Special care should be taken to compensate for these types of extremes and is discussed a bit further below.

Environmental Factors that affect Generator Function

Ambient conditions of temperature are extremely crucial for proper ignition and functioning of a generator. All generators, irrespective of the fuel that powers them, require adequate air for combustion. Decreased air levels can lead to start-up failure. In diesel engines, air and fuel are infused together. The compressed air becomes hot and when peak temperature and pressure is achieved, diesel is injected, which then ignites under the given conditions. In generators using gasoline, an air and fuel mixture is introduced at once using a carburetor and a spark is induced to ignite the engine. However in both cases, adequate levels of air are required for proper start up and operation.

Altitude: In areas of high altitude, air pressure drops reducing the air density. This can create problems with generator start up if not accounted for since air is crucial for ignition in any type of generator. Another factor that gets affected is availability of ambient air to facilitate heat dissipation from the generator. A lot of heat is created during the combustion process and needs to be dissipated into the environment to reduce engine temperature. At high altitudes, due to the low air density, heat dissipation occurs at a much slower rate than it would at sea levels, resulting in high engine temperatures for a sustained period of time. The engine remains hot and overheating is a common problem in such cases.

Temperature: High temperatures are also associated with lower air density and can cause similar ignition problems due to inadequate air supply. This can burden the engine which pushes itself to deliver the power it is designed to. However, due to inadequate oxygen levels available for combustion, it fails to do so. In many such instances, the engine gets overheated and sometimes collapses altogether.

Humidity: Humidity is the measure of water content in a given volume of air. In conditions of extreme humidity, water vapor in the air displaces oxygen. Low oxygen levels impair ignition, since oxygen is the element in air that is ignited in an engine for the burning of fuel.