a measurement of electrical power in an electrical circuit. In DC current, 1VA is equivalent of one 1W (watt). When used with AC current this equation is less precise, because it represents apparent power, which often differs from true power.
A volt-ampere in electrical terms, means the amount of apparent power in an alternating current circuit equal to a current of one ampere at an emf of one volt. It is dimensionally equivalent to watts. An example might be the purchase of an AC transformer rated in electrical terms by volt amperes.