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  2. Per-unit system - Wikipedia

    en.wikipedia.org/wiki/Per-unit_system

    The main idea of a per unit system is to absorb large differences in absolute values into base relationships. Thus, representations of elements in the system with per unit values become more uniform. A per-unit system provides units for power, voltage, current, impedance, and admittance. With the exception of impedance and admittance, any two ...

  3. Reactances of synchronous machines - Wikipedia

    en.wikipedia.org/wiki/Reactances_of_synchronous...

    Technically, these constants are specified in units of the electrical reactance , although they are typically expressed in the per-unit system and thus dimensionless. Since for practically all (except for the tiniest) machines the resistance of the coils is negligibly small in comparison to the reactance, the latter can be used instead of ...

  4. Skin effect - Wikipedia

    en.wikipedia.org/wiki/Skin_effect

    The internal impedance per unit length of a segment of round wire is given by: [6]: 40 = (). This impedance is a complex quantity corresponding to a resistance (real) in series with the reactance (imaginary) due to the wire's internal self- inductance , per unit length.

  5. ESR meter - Wikipedia

    en.wikipedia.org/wiki/ESR_meter

    Measuring ESR can be done by applying an alternating voltage at a frequency at which the capacitor's reactance is negligible, in a voltage divider configuration. It is easy to check ESR well enough for troubleshooting by using an improvised ESR meter comprising a simple square-wave generator and oscilloscope, or a sinewave generator of a few tens of kilohertz and an AC voltmeter, using a known ...

  6. Specific quantity - Wikipedia

    en.wikipedia.org/wiki/Specific_quantity

    Specific relative angular momentum, of two orbiting bodies is angular momentum per unit reduced mass, or the vector product of the relative position and the relative velocity; Specific surface area, per unit of mass, volume, or cross-sectional area; Specific volume, volume per unit mass, i.e. the reciprocal of density

  7. Reaction rate - Wikipedia

    en.wikipedia.org/wiki/Reaction_rate

    Iron rusting has a low reaction rate. This process is slow. Wood combustion has a high reaction rate. This process is fast. The reaction rate or rate of reaction is the speed at which a chemical reaction takes place, defined as proportional to the increase in the concentration of a product per unit time and to the decrease in the concentration of a reactant per unit time. [1]

  8. Antenna (radio) - Wikipedia

    en.wikipedia.org/wiki/Antenna_(radio)

    The antenna gain, or power gain of an antenna is defined as the ratio of the intensity (power per unit surface area) radiated by the antenna in the direction of its maximum output, at an arbitrary distance, divided by the intensity radiated at the same distance by a hypothetical isotropic antenna which radiates equal power in all directions.

  9. Specific weight - Wikipedia

    en.wikipedia.org/wiki/Specific_weight

    The specific weight, also known as the unit weight (symbol γ, the Greek letter gamma), is a volume-specific quantity defined as the weight W divided by the volume V of a material: = / Equivalently, it may also be formulated as the product of density, ρ, and gravity acceleration, g: = Its unit of measurement in the International System of Units (SI) is newton per cubic metre (N/m 3), with ...