Date: 2026-08-19
A variable frequency drive, also called a frequency inverter or VFD, controls the speed and torque of an asynchronous electric motor by changing the frequency and voltage of the supply. It is used in pumps, fans, compressors, conveyors, manufacturing machinery, and other automated systems.
The right choice should not be based only on the power in kW. It is necessary to check the power supply, the rated motor current, the operating mode and the installation conditions.
1. Check the supply voltage
First, determine what power supply the installation has and what voltage the motor requires. The product range offers various configurations, including models with a single-phase 220 V input power supply and models for three-phase 380 V networks.
The input and output voltage of the converter must be compatible with the motor and the electrical grid. It should not be assumed that every inverter can work with every motor.
2. Compare the rated current
The motor power is an important starting point, but its rated current is one of the main selection indicators. The permissible output current of the frequency converter must correspond to the motor current and the intended operating mode.
For applications with heavy starting, frequent accelerations, stops or variable loads, additional technical evaluation is required. Selecting a model based solely on the same kW rating may not be sufficient.
3. Determine the management method
Before purchasing, specify how the start, stop, and speed change commands will be given. Control can be done from a built-in panel, external buttons, a potentiometer, a programmable controller, or an automation system — depending on the capabilities of the specific model.
If remote control is required, check whether an additional operator panel, communication cable or other accessories are required.
4. Adapt the application
- Pumps and fans: speed regulation allows the flow rate to be adapted to actual consumption.
- Conveyors: provides smooth acceleration and adjustment of operating speed.
- Compressors and production machines: the selection must take into account the load and the required starting torque.
- Automated systems: necessary inputs, outputs, and communication capabilities are checked.
5. Provide for proper installation and adjustment
The frequency converter must be installed under the conditions specified by the manufacturer, with the necessary cooling space and appropriate electrical protection. Incorrect parameters may lead to unstable operation or unwanted shutdown of the system.
The settings must be consistent with the data on the motor nameplate — rated voltage, current, frequency, speed, and other parameters required by the specific converter.
Summary
For the right choice, check:
- input and output voltage;
- the rated current and power of the motor;
- the nature of the load;
- the required management method;
- installation and cooling conditions;
- the necessary panels, cables and accessories.
Explore the available E.NEXT frequency converters and compare the technical characteristics of the models.
Important: the selection, connection and adjustment of the frequency converter must be carried out by a qualified specialist in accordance with the motor, the installation and the manufacturer's instructions.