Size Line Bulletin For Free

Line Reactors are rated by % impedance, voltage, and current. However, they are sized by % impedance, voltage, and motor horsepower. The motor horsepower determines the necessary current rating for the Line Reactor.

3% impedance reactors are typically sufficient to absorb power line spikes and motor current surges. They will prevent nuisance tripping of drives or circuit breakers in most applications. 5% impedance reactors are best for reducing harmonic currents and frequencies.

L =XL/(2¶FL) Where L is inductance in Henrys, XL is inductive reactance or impedance in Ohms and F is the frequency. In general Frequency will be the line frequency for both input and output reactors. Your drive distributor should be able to help you size a reactor for use with a drive.

Reactors Percent Impedance: 3% or 5% Line and load reactors are classified by their percent impedance (denoted as percent IZ or %IZ), which is the voltage drop due to impedance, at the rated current, expressed as a percent of rated voltage. The most common line reactors have either 3% or 5% impedance.

If you wish to calculate the value yourself, the following example may be helpful. If a 3% reactor was required for a 100 amp 480 volt drive, a 100 amp or larger current rating would be required. The drive impedance would be: Z=V/I or 480/100 = 4.8 ohms.

The greater the current through the reactor, the greater the percentage of applied impedance will be. If a reactor is said to have an impedance rating of 3% or 5%, that means the reactor will apply that specified percent of impedance when the current flowing through the reactor is at the rated current of the device.

3% impedance reactors are typically sufficient to absorb power line spikes and motor current surges. They will prevent nuisance tripping of drives or circuit breakers in most applications. 5% impedance reactors are best for reducing harmonic currents and frequencies.

%Z = [(Voltage Drop x 100)/Applied Voltage] x ?3. Reactors can be applied to the line and load side of a VFD, each with numerous benefits.