Why and how: Reactive Power symbol is small letter and all other electrical symbol is small letter

All of the symbols in electrical engineering are in capital letter such as “V” for voltage, “A” for ampere etc. You might heard or read of some confusions regarding to the symbol of reactive power. What it should be “VAR” or “var”.

The IEC ( International Electrotechnical Commission) is sole responsible for defining standard for electrical system as well as providing symbols for different parameters.

Correct symbol for reactive power

“var” is the correct symbol for Reactive power. Thus reactive power symbol should be lower case.

As per IEC, the symbol of reactive power should be of lower case when all others are in upper case. So “var” volt-ampere reactive is the correct unit measurement of reactive power.

According to IEC Publ. 27-1, the unit abbreviation is to be in lowercase letters, while other power unit abbreviations are to be in upper case letters. Also, as per EU directive 80/181/EEC (the “metric directive”), the correct symbol is lower-case “var”.

The term “var” first proposed by Romanian electrical engineer Constantin Budeanu in 1930.

Additionally, the unit “var” is allowed by International System of Units (SI). As indicated in IEC website for SI zone, Active power symbol is “P”, Apparent power symbol is “S” and reactive power symbol is “Q” and also, “var”.