Rockwell Automation 1519 MV DRIVE HARMONIC FILTER PF CORRECTION UNIT - Manual (Page 5)

Chapter
1
1519-5.0 – May 1998
Introduction
Functional Description A harmonic filter consists of one or more tuned inductor/capacitor circuits. A
three-phase, iron core reactor is wired in series with three single-phase
individually fused capacitors. These harmonic filters are designed for use with
Bulletin 1557 Medium Voltage Drives.
There are two basic types of standard harmonic filters. Filter Type 1 consists
of an inductor/capacitor combination tuned to the 5 th harmonic (5 times the
fundamental power system frequency) which is designed to reduce harmonics
and provide power factor correction when used in conjunction with a drive
with a 6-pulse rectifier. These Type 1 filters may also be used in conjunction
with drives that have 12-pulse rectifiers. When a 5 th harmonic filter is applied
with a 12-pulse drive it will primarily provide power factor correction and may
provide some degree of harmonic reduction.
Type 2 harmonic filters consist of series inductor/capacitor combinations tuned
for approximately the 5 th , 7 th , and 11 th harmonics and are designed specifically
for use with 12-pulse drives. Drives with 12-pulse rectifiers do not produce
significant amounts of 5 th or 7 th harmonic current, however, the 5 th and 7 th
filters are designed to prevent a potentially detrimental resonance condition
from occurring. Type 2 filters provide harmonic reduction as well as power
factor correction.
Harmonic filters of Type 1 or Type 2 are designed to correct the power factor
to between 0.95 lagging and 0.95 leading over the 50-60% to 100% speed
range for a typical variable torque load.
A particular harmonic filter may or may not allow compliance with the
harmonic current limits specified in IEEE Std 519-1992 (IEEE Recommended
Practices and Requirements for Harmonic Control in Electrical Power
Systems). Calculations need to be carried out which take into account specific
power system data in order to assess compliance with IEEE 519 harmonic
limits for a particular drive application.
Theory of Operation Operating the rectifier of any drive will create harmonic currents that flow
back towards the power source and to other plant loads. These harmonics
result from the non-linearity of the rectifier, which draws a non-sinusoidal
current from a sinusoidal voltage source. The magnitude of the harmonic
currents generated by the rectifier is primarily related to the pulse number of
the rectifier.
1519-IN050B-EN-P June 2013