What is a Line Reactor?
A Line Reactor absorbs many of the power line disturbances which otherwise damage or shut down your
inverters, variable speed controllers, or other sensitive equipment. Line Reactors are the modern
technology solution to inverter and drive application problems.
Many of the AC reactors are harmonic compensated and IGBT
protected to assure optimum performance in the presence of
harmonics. These reactors are very effective at reducing
harmonics produced by inverters and drives, and in most cases,
will help you meet IEEE 519. Use harmonic compensated reactors
on either the input or output of an adjustable speed
There are two types of impedance ratings to choose from in Line
Reactors - three percent or five percent.
3% impedance reactors are usually sufficient to absorb power line spikes and motor current surges.
They will prevent nuisance tripping of drives or circuit breakers in most applications. A 3% impedance
line reactor is typical for the line side of a drive.
5% impedance reactors are best for reducing harmonic currents and frequencies. Use them when you
must comply with IEEE 519, to reduce motor operating temperature, or to reduce motor noise. A 5%
impedance line reactor is used mostly for the load side of a drive.
See the Impedance Rating formula below
Applying Line/Load Reactors
Below four of the most common applications for Line Reactors:
• Input to Inverter/Drive: On the input side of an electronic motor speed controller, line reactors
protect sensitive electronic equipment from electrical noise created by the drive or inverter
(notching, pulsed distortion, harmonics). They also protect the controller from surges, or spikes
on the incoming power lines, we well as reduce harmonic distortion. They help meet the
requirements of IEEE 519.
• Output of Inverter/Drive: In long motor lead applications, use reactors (IGBT protected)
between the inverter and motor to reduce dv/dt and motor terminal peak voltage. The use of a
load (output) reactor also protects the controller from a surge current caused by a rapid change
in the load, and even from a short circuit at the load.
• Multiple Controllers: Multiple drives or inverters on a common power line require one line
reactor per controller. Individual reactors provide filtering between each controller (reduce
crosstalk) and also provide optimum surge protection for each unit. A single line reactor serving
several controllers does not provide adequate protection, filtering or harmonic reduction when
the system is partially loaded.
• Multiple Motors: When more than one motor is controlled by a single drive, a single line reactor
can usually be used between the controller and the motors. The line reactor should be sized
based on the total motor/load horsepower.
Line Reactors are available in 1 - 250 horsepower with 208, 240, 480 and 600 voltage ratings at 60 Hz.
Choose a variety of current options for 3% and 5% impedance. Keep in mind that Line/Load reactors are
selected based upon motor horsepower and voltage ratings. Verify that the drive and motor continuous
current rating is within the fundamental current rating of the reactor before making your final selection
for your application.
Learn more about Line Reactors at the Galco Industrial Electronics Website