Reasons for Limiting Harmonics
IEEE Standard 519-1992 explains the reasons
for limiting harmonics and recommends limits
to be applied in various situations. The harmonic
currents drawn by a load cause extra heating
in all of the power distribution equipment that
supplies the load. Harmonic voltages are generated
by the action of the harmonic currents flowing
in all of the impedances in the system from the
utility generating and transmission system and
the substation and distribution transformers to
the branch circuit protective devices and wiring.
Harmonic voltages cause additional harmonic
currents to flow in equipment that does not
ordinarily draw harmonic currents. Harmonics
can interfere with the operation of some sensitive
equipment.
For more detailed information about harmonics,
refer to ABB publications Fact File TD2 EN
Reducing harmonics caused by variable speed
drives and Technical Guide No. 6 Guide to
Harmonics with AC Drives.