Frequency Drives and Their Electromagnetic Compatibility
The topic of frequency drives and their compatibility is often discussed at conferences and exhibitions. It is important to define what electromagnetic compatibility is: it is the ability of technical devices to operate simultaneously in real operational conditions with the required quality, under the influence of spontaneous electromagnetic interference, as well as to avoid interfering with other devices.
Converters, using electromagnetic oscillations, form “spontaneous electromagnetic interference.” During operation, frequency drives generate higher harmonics, which can affect the efficiency of power transformers, capacitor components of compensation stations, and radio-electronic devices connected to the network.
In addition to harmonics, converters also cause radio interference that penetrates the electrical network and is emitted into the surrounding space.
Reduction of Higher Harmonics
To reduce the magnitude of higher harmonics, it is important to improve the shape of the current generated by the frequency drive. Such devices include:
- input power AC chokes;
- passive harmonic filters;
- active higher harmonic filters, which belong to the latest group of devices that enhance the quality of electrical energy.
Harmonic filters and active filters are usually supplied separately and installed near the frequency drive. Recently, the company Bosch Rexroth has started producing converters EFC3610 and EFC5610 with built-in filters.
Reduction of Radio Interference
Radio interference created by frequency drives can be reduced using RFI filters. It is worth noting that different RFI filters reduce the level of radio interference differently. If the converter is connected to a transformer, and there are no other devices, the filtering element can be ignored. However, if the frequency drive is controlled by an external controller, or other electronic devices are connected, it is advisable to choose a converter with a high-quality RFI filter.
Use of Frequency Drives in Industry
Stationary and onboard special-purpose devices use frequency drives to generate sinusoidal voltage with the necessary frequency and amplitude. All manufacturers of frequency drives recommend using shielded control cables, the shield of which is grounded on both sides.
The issue of electromagnetic compatibility remains a complex topic for discussion, as it is not easy to describe mathematically or to model. If you have any questions regarding this matter, please contact us at our service center. Our many years of experience in operating frequency drives may be beneficial to you.