VTdrive Selecting a Line Reactor for Variable Speed Drive(VSD)0 pages

The benefits of the right line reactor - for drives and motors.

A line reactor can enhance performance, life expectancy and efficiency for motors and drives. Line

reactors serve as a current limiting device for harmonic and transient waveforms, and can make a

tremendous impact. Nuisance tripping, heat, noise, and premature failure are a few problems that

can typically be resolved with the added impedance provided by a line reactor.

Without a reactor - high peaks, shorter wave

Source Rockwell Automation - Mequon Wisconsin

With a reactor - lower peaks, longer wave

The added impedance of the line reactor lowers the current peak while extending the wave further

over time. Line reactors are usually rated by the percent impedance (Z) they will add to the circuit

(1.5%, 3%, 5%). A good rule of thumb for most industrial applications is 3%. The percent

impedance can provide an indication as to how much voltage drop occurs across the reactor, and is

calculated by:

%Z = [(Voltage Drop x 100)/Applied Voltage] x V3.

Reactors can be applied to the line and load side of a VFD, each with numerous benefits. A few of

those benefits include:

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Line circuit - >*—^ Reducing Extending

minimizing harmonic distortion VFD faults Motor Life

Reduce tripping in switchgear (solid state Reduce tripping from line sags and peaks Lower temperatures (up to 20° C).

sensing devices). Reduces Current surges from Voltage Reduced noise from PWM, by 3-6db,

Reduce harmonic peaks generated by drive. Transients Reducing impact of reflected wave.

Selecting a Line Reactor for VFD applications

There are several line reactors on the market from very reputable suppliers. When looking for you

next line reactor, be sure to consider: