Harmonic Analysis and IEEE 1992 Guidelines
Introduction
IEEE 519-1992 provides guidelines for applying limits to the level of harmonic distortion that a utility
customer may inject into the power system. This is a concern, since Adjustable Frequency Drives (AFDs) can contribute significant harmonic distortion to a power system. The guidelines pertain to percent
harmonic current and voltage distortion at the point of common coupling (PCC), which is defined as the point where the utility connects to multiple customers.
Although many customers and system designers interpret the PCC to be at the AFD input or various locations within the  480V distribution, this is not consistent with the intent of IEEE guidelines. There are no limits recommended for individual loads, only for the overall system. Customers and system designers can choose the point of analysis (POA) where they desire, but it may add substantial filtering costs if the POA is downstream of the PCC.
Current distortion drawn through an impedance (transformer, cable resistance) causes voltage
distortion.The distorted current will also cause additional heating of the input cables and the transformer. Excessive voltage distortion is a concern, since it may cause interference with other electronic equipment and additional motor heating.
IEEE 519-1992 recommends different limits on Individual Harmonics (I h ) and Total Demand Distortion (TDD), depending on the I SC /I L  ratio. I SC  is the short circuit current at the PCC, and I L  is the maximum demand load current (fundamental) at the PCC. More current distortion is allowed at higher I SC /I L  ratios, since voltage distortion decreases as the ratio increases.
The voltage distortion guidelines for IEEE-1992 (at 480V) remain the same as IEEE 519-1981:
∙ 3% — Special systems (i.e. hospitals or universities) ∙ 5% — General systems
∙ 10% —
Dedicated systems (AFDs only)
Application Note AP04014002E
Harmonic Analysis and IEEE 1992 Guidelines
Effective July 2014
2 EATON CORPORATION  www.eaton
The best way to estimate AFD harmonic contribution to an electrical system is to perform a harmonic
analysis based on known system characteristics. An individual AFD may meet the IEEE guidelines in one system and not meet the guidelines in another system depending on the pre-existing characteristics of the specific system.
Some AFD vendors, upon seeing a specification requirement for IEEE 519-1992, will simply add a line reactor. This is the wrong approach, since some systems will not require a line reactor and others will not benefit sufficiently to meet the guidelines (or the specification).
For a free computerized harmonic analysis of AFD contribution to system harmonics or for additional information, contact your local Eaton sales office. A one-line drawing of the electrical distribution system and specification criteria will be required. A harmonic analysis worksheet for required data is attached.
Any additional harmonic mitigation equipment requirements will be determined during the analysis. If there are harmonic constraints during AFD operation on a standby generator, a separate analysis will be required for the generator, and assumptions on load-shedding strategies during generator operation
should be provided. Several data runs may be required to evaluate various harmonic mitigation methods. Resultant recommendations may include 1%, 3%, or 5% line reactors, phase-shifting transformers, filters, or CPX9000 Clean Power.
Helpful Facts
∙ Harmonics are supply system dependent. As the short circuit amps available (SCA) increase, %
voltage distortion decreases, and % current distortion increases.
∙ For each PCC or POA analysis required, provide SCA and IL (load current) values for that point. SCAs used must be without motor contribution to SCA.
∙
Current distortion percentages are dependent on overall system loading. As linear loads (non-harmonic loads such as AC motors on line power) increase, the percent current distortion decreases through dilution.
∙ % current distortion is the same across a transformer. Voltage distortion percentage is lower on the primary than on the secondary, assuming the harmonic loads are on the secondary. ∙
A harmonic analysis is only as accurate as the assumptions made for the analysis!
Harmonic Analysis Data Worksheet
(Use separate sheets if necessary. Provide a 1-line drawing or sketch.)
lated voltage distortion and higher calculated current distortion on the transformer secondary.
Distribution Transformer(s) Data:
Generator Data:
Describe load-shedding scheme for generator operation in “AFD Data” below.
AFD Data:
kVA
Impedance
X/R Ratio
#1#2
kW kVA
Volts
X"d
I  L  (amps)
#1#2
AFD hp
Type (SVX9000,Clean Power, etc.)
Quantity Operated on Line / Generator
ac reactorDesired, existing or specified line reactor or isolation transformer (none, 1% / 3% / 5%)
//////
Application Note AP04014002E Effective July 2014
Harmonic Analysis and IEEE 1992 Guidelines
3                EATON CORPORATION www.eaton
Application Note AP04014002E Harmonic Analysis and IEEE 1992 Guidelines Effective July 2014
Additional Help
In the US or Canada: please contact the Technical Resource Center at 1-877-ETN-CARE
or 1-877-326-2273 option 2, option 6.
All other supporting documentation is located on the Eaton web site at www.eaton/Drives
Eaton
1000 Eaton Boulevard
Cleveland, OH 44122 USA
Eaton
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All Rights Reserved
Printed in USA
Publication No.AP04014002E
July 2014
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