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If energy output and input are expressed in the same units, efficiency is a dimensionless number. [1] Where it is not customary or convenient to represent input and output energy in the same units, efficiency-like quantities have units associated with them. For example, the heat rate of a fossil fuel power plant may be expressed in BTU per ...
is the voltage at maximum load. The maximum load is the one that draws the greatest current, i.e. the lowest specified load resistance (never short circuit); is the voltage at minimum load. The minimum load is the one that draws the least current, i.e. the highest specified load resistance (possibly open circuit for some types of linear ...
Conversely, when the output current is (near) zero, the voltage at the load is higher. This follows from Ohm's law. Rather than increasing output voltage at high current to try to maintain the same load voltage, droop instead simply allows this drop to take place and designs around it. The behaviour of the system with and without droop is as ...
Output power factor remains in the range of 0.96 or higher from half to full load. Because it regenerates an output voltage waveform, output distortion, which is typically less than 4%, is independent of any input voltage distortion, including notching. Efficiency at full load is typically in the range of 89% to 93%.
Low-power or insulated versions of these devices give off less heat for the air conditioning to remove. The air conditioning system can also improve efficiency by using a heat sink that is cooler than the standard air heat exchanger, such as geothermal or water. In cold climates, heating air and water is a major demand for household energy use.
To express the efficiency of a generator or power plant as a percentage, invert the value if dimensionless notation or same unit are used. For example: A heat rate value of 5 gives an efficiency factor of 20%. A heat rate value of 2 kWh/kWh gives an efficiency factor of 50%. A heat rate value of 4 MJ/MJ gives an efficiency factor of 25%.
The wall-plug efficiency is the measure of output radiative-energy, in watts (joules per second), per total input electrical energy in watts. The output energy is usually measured in terms of absolute irradiance and the wall-plug efficiency is given as a percentage of the total input energy, with the inverse percentage representing the losses.
A low line regulation is always preferred. In practice, a well regulated power supply should have a line regulation of at most 0.1%. [1] In the regulator device datasheets the line regulation is expressed as percent change in output with respect to change in input per volt of the output. Mathematically it is expressed as: