What is the advisable minimum frequency for a 50Hz motor (SEW)?

For 50Hz motors, especially brand motors like SEW, there is a recommended minimum operating Frequency when using a Variable Frequency Drive (VFD) for speed control. According to the information you provided, the ordinary motor under the control of the inverter, can not be lower than 20Hz, below 20Hz will lose control. This means that, in most cases, when a 50Hz motor is operated under the control of a frequency converter, the minimum frequency should not be lower than 20Hz.

Minimum frequency considerations

• Motor design: The design of the motor is usually 50Hz as the reference frequency, when the frequency is reduced, the performance of the motor (such as torque, power) will also be affected.

• Control performance: Frequency below a certain threshold may cause the control of the motor to become unstable, for example, the speed of the motor may become difficult to control.

• Heat dissipation problems: When the frequency is reduced, the speed of the motor is also reduced, which may lead to heat dissipation problems because the cooling efficiency of the fan will be reduced.

• Mechanical resonance: Reducing the frequency may cause the motor to operate near the mechanical resonance frequency, which may cause the motor to shake more and affect its service life.

• Electromagnetic interference: When operating at low frequencies, the motor may produce more electromagnetic interference (EMI), which may have an impact on surrounding electronic equipment.

SEW motor special case

SEW motor as an industrial grade motor, its design is usually able to adapt to a certain frequency range. However, even a high-quality motor such as SEW has its minimum frequency limit. If you need to run the motor at a frequency below 50Hz, it is usually recommended not to run below 20Hz. This is to ensure the stable operation of the motor and extend the service life of the motor.

Precautions when using frequency converter

When using a frequency converter to control the speed of the motor, the following points should be noted:

• Frequency regulation: The frequency should be gradually adjusted to avoid mutations to prevent the motor and load from being impacted.

• Load matching: Ensure that the capacity of the inverter matches the motor to avoid overload or underload.

• Protection Settings: Correctly set the protection function of the inverter, such as over current, over voltage, under voltage protection.

• Maintenance: Regularly check the status of the motor and inverter, timely maintenance.

Sum up

For SEW motors at 50Hz, the recommended minimum frequency should generally not be less than 20Hz. This is mainly to ensure the stable operation of the motor, prevent control instability, avoid heat dissipation problems, reduce mechanical resonance and reduce electromagnetic interference. In practical applications, the appropriate operating frequency should be selected according to the specific working conditions and the recommendations of the motor manufacturer. If you need to operate at lower frequencies, you should consult a professional motor supplier or technician to ensure that the motor can work safely and reliably.