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As a result of the maximum power theorem, devices transfer maximum power to a load when running at 50% electrical efficiency. This occurs when the load resistance (of the device in question) is equal to the internal Thevenin equivalent resistance of the power source. This is valid only for non-reactive source and load impedances.
Efficiency of power plants, world total, 2008. Energy conversion efficiency (η) is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be chemical, electric power, mechanical work, light (radiation), or heat.
Although it is named "power usage effectiveness", it actually measures the energy use of the data centre. [10] The PUE metric has several important benefits. First, the calculation can be repeated over time, allowing a company to view their efficiency changes historically, or during time-limited events like seasonal changes.
It is an addition to the power usage effectiveness (PUE) definition and was first proposed by Greenqloud. [1] The Green Grid has developed the Power Usage Effectiveness metric [2] or PUE to measure a data centers' effectiveness of getting power to IT equipment. What the PUE tells in simple terms is how much extra energy is needed for each ...
The problems unique to this approach are: (1) it costs time and energy to transition between active and idle power-down states, (2) no work can be done in the off state, so power-up must be done to handle a request, and (3) predicting idle periods and adapting appropriately by choosing the right power state at any moment is difficult.
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%.
Since the power equals thrust times speed, the efficiency is given by η = V / ( S F C × h ) {\displaystyle \eta =V/(SFC\times h)} where V is speed and h is the energy content per unit mass of fuel (the higher heating value is used here, and at higher speeds the kinetic energy of the fuel or propellant becomes substantial and must be included).
Data center infrastructure efficiency (DCIE), is a performance improvement metric used to calculate the energy efficiency of a data center. DCIE is the percentage value derived, by dividing information technology equipment power by total facility power.