How to Correctly Select VFD (Variable-frequency Drive) Auxiliary Line and Output Reactor

We know that VFD (Variable-frequency Drive) is often used in various electrical environments. If timely protection measures are not taken, the stability and reliability of VFD (Variable-frequency Drive) operation will definitely be affected.

Through the investigation, it is found that the matching of the reactor with the VFD (Variable-frequency Drive) can better prevent the impact of the overvoltage and surge current caused by the operation of the AC incoming line switch, and at the same time reduce the impact of the VFD. (Variable-frequency Drive) The harmonics generated by the VFD (Variable-frequency Drive) will pollute the power grid and can improve the power factor of the VFD (Variable-frequency Drive). Therefore, how to correctly select VFD (Variable-frequency Drive) accessories - incoming and outgoing line reactors is very necessary.

1. About the selection of Chengdu Sunwoele VFD (Variable-frequency Drive) line reactor

1. Impedance voltage drop: Impedance voltage drop refers to the actual voltage drop at both ends of the reactor coil corresponding to the actual rated current at 50HZ. Usually, the impedance voltage drop is selected to be around 2-4%.

2. Selection of inductance: The rated inductance of the reactor is also an important parameter! If the inductance is not selected properly, it will directly affect the change of the impedance voltage drop under the rated current, thus causing a fault. The size of the inductance depends on the cross-sectional area of the reactor core and the number of turns of the coil and the adjustment of the air gap. The inductance is determined by selecting the rated AC current and impedance voltage drop.

3. Selection of rated AC current: The rated AC current is the long-term working current of the reactor designed from the aspect of heat generation, and sufficient high-order harmonic components should be considered at the same time. That is, the actual current flowing through the input reactor is the input current of VFD (Variable-frequency Drive).

2. Regarding the selection of output reactors for Chengdu Sunwoele VFD (Variable-frequency Drive)

1. Impedance voltage drop: Impedance voltage drop refers to the actual voltage drop across the reactor coil corresponding to the actual rated current at XHz. Usually, the impedance voltage drop is selected to be around 1-4%.

2. Selection of inductance: The rated inductance of the reactor is also an important parameter! If the inductance is not selected properly, it will directly affect the change of the voltage drop under the rated current and cause a fault. The size of the inductance depends on the cross-sectional area of the reactor core and the number of turns of the coil and the adjustment of the air gap. The selection of the inductance of the output reactor is mainly determined according to the length of the cable within the rated frequency range, and then according to the actual rated current of the motor, the cross-sectional area of the iron core and the cross-sectional area of the wire under the corresponding inductance requirements can be selected to determine the actual voltage drop. .

3. The inductance and cable length corresponding to the rated current: the rated output current inductance of the cable length.

4. Selection of rated AC current: The rated AC current is the long-term working current of the reactor designed from the aspect of heat generation, and sufficient high-order harmonic components should be considered at the same time. That is, the current actually flowing through the output reactor is the output current of the VFD (Variable-frequency Drive) motor load.