This recommended practice establishes goals for the design of
electrical systems that include both linear and nonlinear loads.
The voltage and current waveforms that may exist throughout the
system are described, and waveform distortion goals for the system
designer are established. The interface between sources and loads
is described as the point of common coupling and observance of the
design goals will minimize interference between electrical
This recommended practice addresses steady-state limitations.
Transient conditions exceeding these limitations may be
encountered. This document sets the quality of power that is to be
provided at the point of common coupling. This document does not
cover the effects of radio-frequency interference; however,
guidance is offered for wired telephone systems.
This recommended practice is to be used for guidance in the
design of power systems with nonlinear loads. The limits set are
for steady-state operation and are recommended for "worst case"
conditions. Transient conditions exceeding these limits may be
encountered. In any case, the limit values given in this document
are recommendations and should not be considered binding in all
cases. Because of the nature of the recommendations, some
conservatism is present that may not be necessary in all cases.
This recommended practice should be applied at interface points
between system owners or operators and users in the power system.
The limits in this recommended practice are intended for
application at a point of common coupling (PCC) between the system
owner or operator and a user, where the PCC is usually taken as the
point in the power system closest to the user where the system
owner or operator could offer service to another user. Frequently
for service to industrial users (i.e., manufacturing plants) via a
dedicated service transformer, the PCC is at the HV side of the
transformer. For commercial users (office parks, shopping malls,
etc.) supplied through a common service transformer, the PCC is
commonly at the LV side of the service transformer.
The limits in this recommended practice represent a shared
responsibility for harmonic control between system owners or
operators and users. Users produce harmonic currents that flow
through the system owner's or operator's system which lead to
voltage harmonics in the voltages supplied to other users. The
amount of harmonic voltage distortion supplied to other users is a
function of the aggregate effects of the harmonic current producing
loads of all users and the impedance characteristics of the supply
system. Harmonic voltage distortion limits are provided to reduce
the potential negative effects on user and system equipment.
Maintaining harmonic voltages below these levels necessitates
- All users limit their harmonic current emissions to reasonable
values determined in an equitable manner based on the inherent
ownership stake each user has in the supply system and
- Each system owner or operator takes action to decrease voltage
distortion levels by modifying the supply system impedance
characteristics as necessary.
In order to allow the system owner or operator to control the
system impedance characteristics to reduce voltage distortion when
necessary, users should not add passive equipment that affects the
impedance characteristic in a way such that voltage distortions are
increased. In effect, such actions by a user could amount to
producing excessive voltage harmonic distortion. Such passive
equipment additions (that lead to undesirable system impedance
characteristics) should be controlled by the user in the same
manner as current harmonic-producing devices operated by the
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