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400 V low voltage secondary side distribution transformer with primary 12 kV; 200 kVA (up to 1000 kVA also common) [7] 10 3: 2 kA 10.5 kV secondary side from an electrical substation with primary 115 kV; 63 MVA [8] 9.3 kA 2.7V, Ultracapacitor short circuit current [9] 10 4: 25 kA Lorentz force can crusher pinch [10] 30 kA Typical lightning ...
The volt-ampere (SI symbol: VA, [1] sometimes V⋅A or V A) is the unit of measurement for apparent power in an electrical circuit.It is the product of the root mean square voltage (in volts) and the root mean square current (in amperes). [2]
An important property of three-phase power is that the instantaneous power available to a resistive load, = =, is constant at all times.Indeed, let = = To simplify the mathematics, we define a nondimensionalized power for intermediate calculations, =
The base value should only be a magnitude, while the per-unit value is a phasor. The phase angles of complex power, voltage, current, impedance, etc., are not affected by the conversion to per unit values. The purpose of using a per-unit system is to simplify conversion between different transformers.
The ampere is named for French physicist and mathematician André-Marie Ampère (1775–1836), who studied electromagnetism and laid the foundation of electrodynamics.In recognition of Ampère's contributions to the creation of modern electrical science, an international convention, signed at the 1881 International Exposition of Electricity, established the ampere as a standard unit of ...
The N700 Shinkansen uses a three-level converter to convert 25 kV single-phase AC to 1,520 V AC (via transformer) to 3 kV DC (via phase-controlled rectifier with thyristor) to a maximum 2,300 V three-phase AC (via a variable voltage, variable frequency inverter using IGBTs with pulse-width modulation) to run the motors.
A simple arithmetic calculator was first included with Windows 1.0. [5]In Windows 3.0, a scientific mode was added, which included exponents and roots, logarithms, factorial-based functions, trigonometry (supports radian, degree and gradians angles), base conversions (2, 8, 10, 16), logic operations, statistical functions such as single variable statistics and linear regression.
The factor–label method can convert only unit quantities for which the units are in a linear relationship intersecting at 0 (ratio scale in Stevens's typology). Most conversions fit this paradigm. An example for which it cannot be used is the conversion between the Celsius scale and the Kelvin scale (or the Fahrenheit scale). Between degrees ...