Frequency converters generate high-frequency interference in the PWM output signal that causes EMI, motor load, and cable length limitations. Block's SF4 all-pole sine filters convert this PWM signal into a virtually pure sine voltage on the motor side.
The filters suppress both differential and common-mode components, leading to lower EMC emissions on motor cables, reduced leakage currents to ground, reduction of bearing currents, and lower thermal load on the motor and cable. This increases reliability and extends the service life of the drive system.
In applications such as pumps, fans, and conveyor belts with long cables, overvoltage spikes, reflections, and EMC problems occur without filtering. SF4 filters limit these effects and keep the motor voltage stable, allowing for longer cable runs. In certain configurations, this can also lead to approximately 5% higher system efficiency.
The distinguishing feature of the SF4 is that common-mode currents are internally returned to the DC link instead of via ground. This reduces ground leakage currents and EMC load and offers higher effectiveness than classic du/dt filters or output chokes.
Electrical specifications
- 3 × 500 Vac
- 5–150 Hz output frequency
- ≥4 kHz switching frequency
- 2.2–90 kW
- 5,2–165 A
For long motor cables and high EMC requirements, sine wave filtering is essential. The SF4 series reduces PWM-related interference and improves both EMC performance and the lifespan of the motor and the installation.
The message Less EMI, lower motor load and longer motor cables first appeared on Elincom.
Source: https://www.elincom.nl/nieuws/minder-emi-lagere-motorbelasting-en-langere-motorkabels/