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  2. Volt-ampere - Wikipedia

    en.wikipedia.org/wiki/Volt-ampere

    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] Volt-amperes are usually used for analyzing alternating current (AC) circuits.

  3. AC power - Wikipedia

    en.wikipedia.org/wiki/AC_power

    Apparent power is often expressed in volt-amperes (VA) since it is the product of RMS voltage and RMS current. The unit for reactive power is var, which stands for volt-ampere reactive . Since reactive power transfers no net energy to the load, it is sometimes called "wattless" power.

  4. Alternating current - Wikipedia

    en.wikipedia.org/wiki/Alternating_current

    A schematic representation of long distance electric power transmission. From left to right: G=generator, U=step-up transformer, V=voltage at beginning of transmission line, Pt=power entering transmission line, I=current in wires, R=total resistance in wires, Pw=power lost in transmission line, Pe=power reaching the end of the transmission line, D=step-down transformer, C=consumers.

  5. Power rating - Wikipedia

    en.wikipedia.org/wiki/Power_rating

    Power ratings are usually given in watts for real power and volt-amperes for apparent power, although for devices intended for use in large power systems, both may be given in a per-unit system. Cables are usually rated by giving their maximum voltage and their ampacity . [ 4 ]

  6. Per-unit system - Wikipedia

    en.wikipedia.org/wiki/Per-unit_system

    Moreover, similar types of apparatus will have the impedances lying within a narrow numerical range when expressed as a per-unit fraction of the equipment rating, even if the unit size varies widely. Conversion of per-unit quantities to volts, ohms, or amperes requires a knowledge of the base that the per-unit quantities were referenced to.

  7. Wattmeter - Wikipedia

    en.wikipedia.org/wiki/Wattmeter

    For each sample, the voltage is multiplied by the current at the same instant; the average over at least one cycle is the real power. The real power divided by the apparent volt-amperes (VA) is the power factor. A computer circuit uses the sampled values to calculate RMS voltage, RMS current, VA, power (watts), power factor, and kilowatt-hours.

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  9. Watt - Wikipedia

    en.wikipedia.org/wiki/Watt

    In terms of electromagnetism, one watt is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potential difference of one volt (V), meaning the watt is equivalent to the volt-ampere (the latter unit, however, is used for a different quantity from the real power of an electrical circuit).