A reactor is an electronic component used to limit current and smooth the output voltage.

In the actual operation of a VFD, when is it necessary to install a reactor, and what are its advantages?

Reactors are generally used in the following situations:

1. Long-distance connections: When the distance between the VFD and the motor exceeds 30 meters, it is recommended to install a reactor to compensate for the effects of distributed capacitance caused by the distance and to suppress harmonic components in the output of general-purpose VFDs.

2. Harmonic interference: In monitoring and communication equipment, harmonic interference from the inverter side of the VFD may prevent surrounding electrical equipment from functioning properly. Furthermore, harmonic interference can cause issues such as vibration and overheating; in severe cases, it may damage the motor. Therefore, a reactor is needed to counteract these harmonics.

3. High Power Capacity or Voltage Unbalance: When the power capacity is very high or the voltage unbalance exceeds 3%, it is recommended to install a reactor to prevent voltage-induced current surges. This not only protects the inverter but also improves the power factor.

4. Shared Power Supply with Thyristor Equipment: When a variable frequency drive shares a transformer with thyristor equipment or reactive power compensation equipment, it is best to install an input reactor to reduce the impact of voltage harmonics on the variable frequency drive.

The advantages of using a reactor are as follows:

1. Extended Service Life: Reactors can suppress surge voltages and surge currents, effectively protecting the electronic components inside the variable frequency drive and preventing damage. Furthermore, reactors filter out harmonics and waveform distortion, ensuring stable operation of the inverter.

2. Improved power factor: An input reactor can effectively improve the inverter’s power factor and enhance power quality. At the same time, the reactor suppresses harmonic currents, ensuring stable operation of the power grid.

3. Extend Effective Transmission Distance: Output reactors can extend the effective transmission distance of the inverter, ensuring stability even with long cables.

4. Reduce Motor Noise: Output reactors can effectively reduce motor noise while also lowering eddy current losses and improving operational efficiency.

5. Protect Internal Power Switching Devices: Reactors can effectively suppress the transient high voltage generated when the inverter’s IGBT modules switch, preventing damage to the power switching devices caused by high voltage.