Parasitic load is a term used with regard to electrical appliances and railway locomotive

Locomotive

A locomotive is a railway vehicle that provides the motive power for a train. The word originates from the Latin loco – "from a place", ablative of locus, "place" + Medieval Latin motivus, "causing motion", and is a shortened form of the term locomotive engine, first used in the early 19th...

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With regard to electrical appliances, it represents the power consumed even when the appliance is shut off, that is standby power

Standby power

Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity , refers to the electric power consumed by electronic and electrical appliances while they are switched off Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity...

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With regard to railway locomotives, it is any of the loads or devices powered by the diesel

Diesel engine

A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

 prime mover

Prime mover (locomotive)

In engineering, a prime mover is an engine that converts fuel to useful work. In locomotives, the prime mover is thus the source of power for its propulsion. The term is generally used when discussing any locomotive powered by an internal combustion engine...

 not contributing to tractive effort

Tractive effort

As used in mechanical engineering, the term tractive force is the pulling or pushing force exerted by a vehicle on another vehicle or object. The term tractive effort is synonymous with tractive force, and is often used in railway engineering to describe the pulling or pushing capability of a...

, such as air compressor

Air compressor

An air compressor is a device that converts power into kinetic energy by compressing and pressurizing air, which, on command, can be released in quick bursts...

, traction motor blower, or radiator

Radiator

Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics...

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With regard to electricity production, it is any of the loads or devices powered by the wind generator, not contributing to net electric yield found by subtracting productive yield from gross yield or

GY - PY = PL where

"GY" is gross electric yield (the output of the generator;
"PY" is productive yield (the electricity which is made available to external electric loads);and
"PL" is parasitic load.