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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.
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.
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.
For this calculation, it is conventional to define a normalized rate = / (), a bandwidth utilization parameter of bits per second per half hertz, or bits per dimension (a signal of bandwidth B can be encoded with dimensions, according to the Nyquist–Shannon sampling theorem). Making appropriate substitutions, the Shannon limit is:
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 red curve shows the power in the load, normalized relative to its maximum possible. The dark blue curve shows the efficiency η. The efficiency η is the ratio of the power dissipated by the load resistance R L to the total power dissipated by the circuit (which includes the voltage source's resistance of R S as well as R L):
In power engineering, the power-flow study, or load-flow study, is a numerical analysis of the flow of electric power in an interconnected system. A power-flow study usually uses simplified notations such as a one-line diagram and per-unit system, and focuses on various aspects of AC power parameters, such as voltages, voltage angles, real power and reactive power.
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).