Tamara Wilhite is a technical writer, industrial engineer, mother of two, and published sci-fi and horror author.
What is IEEE 519?
IEEE 519 is intended to limit the negative impact of non-linear power system loads.
Power system harmonics became an issue in electrical system design as static power converter drives with capacitors came into widespread use in the 1970s. Power system harmonics started to damage sensitive electronics and control systems.
IEEE 519 provides a standard method to measure current harmonics and voltage harmonics and sets recommended guidelines for power system harmonics.
Unlike electrical standards like the National Electric Code (NEC) and National Electric Safety Code (NESC), IEEE 519 is only a recommendation and has never been adopted as law.
What the IEEE 519 Standard Says
IEEE 519 refers to the connection point between the utility line and the building’s power system as the Point of Common Coupling or PCC. The PCC is generally a medium voltage (MV) transformer or low voltage (LV) transformer.
IEEE standard 519 also contains recommendations for harmonic controls for devices with reactive components like rectifiers and capacitors. IEEE 519 is intended to measure power harmonics on power system connections between a utility line and a building.
Electrical power systems can experience harmonics in both the current and the voltage. Alternating current systems naturally experience some variation, but variations more than a few percent can burn out electrical components like capacitors and inductors. When the voltage frequency varies, capacitors convert this into a current that varies even more.
IEEE standard 519 recommends a maximum Total Harmonic Distortion or THD of 5% for both current and voltage for low voltage lines. IEEE 519 demands lower voltage distortion on high voltage lines over 69 kilovolts or 69 kV.
IEEE standard 519 recommends that no single harmonic contributes more than 3% of the current harmonics or 1% of the voltage harmonics. IEEE recommends individual voltage distortion of 1.5% or less for power lines with PCC voltage from 69 to 151 kilovolts and a total voltage distortion of 2.5% or less. Each harmonic on a power line contributes to the total harmonic distribution. IEEE standard 519 recommends individual voltage distortion of 1% or less for lines with 161 kilovolts or more and total voltage distortion of 1.5% or less.
Measuring Power System Harmonics
The baseline Total Harmonic Distortion or THD is the incoming current and voltage of the power coming from the utility. Voltage distortion is measured from the sine wave form of the incoming alternating current voltage. Measurements for total harmonic distortions should be taken in one minute intervals.
The harmonics should be measured before a piece of equipment is turned on and after has been started up. Voltage and current harmonics must be measured separately, since they are related but not the same thing. However, if the voltage varies significantly, so will the current.
What IEEE 519 Does Not Cover
IEEE 519 does not address electromagnetic interference (EMI) or radio-frequency (RF) interference in electrical systems.
IEEE 519’s recommended guidelines on power system harmonics can be applied to individual power lines within a facility, but IEEE standard 519 does not apply to commercial, residential or industrial power systems within a facility.
History of IEEE 519
IEEE std 519 was originally published in 1981. IEEE 519-1981 initially applied to static power converters. IEEE 519 was updated in 1991. IEEE 519A is a proposed revision to IEEE 519 to provide a better definition of a PCC and describe a method of measuring the demand current after equipment. The IEEE standard 519 was updated in 2014.