at 220 volts can deliver a current of 1818 amperes (these are RMS values). VA ratings are also often used for transformers; maximum output current is then VA rating divided by nominal output voltage. Transformers with the same sized core usually have the same VA rating. The convention of using the volt-ampere to distinguish apparent power from real power is allowed by the SI standard. Volt-ampere reactive In electric power transmission and distribution, volt-ampere reactive (var) is a unit of measurement of reactive power. Reactive power exists in an AC circuit when the current and voltage are not in phase. The term var was proposed by the Romanian electrical engineer Constantin Budeanu and introduced in 1930 by the IEC in Stockholm, which has adopted it as the unit for reactive power. Special instruments called varmeters are available to measure the reactive power in a circuit. The unit "var" is allowed by the International System of Units (SI) even though the unit var is representative of a form of power. SI allows one to specify units to indicate common sense physical considerations. Per EU directive 80/181/EEC (the "metric directive"), the correct symbol is lower-case "var", although the spellings "Var" and "VAr" are commonly seen, and "VAR" is widely used throughout the power industry. References Electricity Units of power