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Frequency Converter SD4S: Stand-alone Device with Wide Power Range

Press releases
Frequency converter SD4S

The product variant SD4S - S for stand-alone - marked the beginning of the new SD4x series by SIEB & MEYER. These frequency converters succeed the well-proven SD2S devices and they are suited to stationary applications in switch cabinets for machine tools or turbo blowers/compressors.


The frequency converter SD4S is available in different sizes in the 50-V and 230-V class. In 2023, additional models in the 400-V class will be launched. Together these devices cover the current power range (1.4...55 kVA) of the SD2S series and even extend it downwards and upwards (0.8...66 kVA).

SD4S provides PWM frequencies up to 32 kHz and commutation frequencies up to 64 kHz. This results in higher rotating field frequencies up to 6,000 Hz and reduced harmonic frequency components. Users can realize motor designs with more motor poles and benefit from lower motor losses. Another advantage: the input for the thermal contact is galvanically isolated from logic and mains supply, which ensures safe operation even with insulation problems of the thermal contact in the motor. With the software tool Motor Analyzer, users can simulate the operating points and carry out an FFT analysis with calculation of the THDi and THDu values. This way, the system performance can be analyzed already at the beginning of the development.

By the way: SD4S enables efficient operation of synchronous motors with magnets embedded in the rotor, so-called interior permanent magnet motors (IPM). The reluctance torque generated by these motors is optimized in real-time depending on the operating point.