The drive to cut harmonics
With its new SED2 variable speed drives and the free HarmonEE software package, Siemens Building Technologies has launched a two-pronged attack on the generation of power system harmonics in building services installations – a subject which is now of greater importance than ever following the recent introduction of the new ERG5/4-1 planning guidelines for harmonic voltage distortion.
Unlike most drives currently available, the new SED2 models feature a design which has been carefully optimised for fan and pump applications in buildings, rather than for general purpose use in industry. This has made it possible for Siemens to incorporate innovative Low Harmonic Technology (LHT) circuitry which allows the drives to deliver excellent harmonic performance without the need for bulky, inconvenient and often expensive filters and chokes.
SED2 drives are available with ratings from 0.37kW to 90kW in IP20/21 versions and 1.1kW to 90kW in IP54 versions, making them suitable for virtually all building services pump and fan applications. All models incorporate integral PID controllers to facilitate accurate flow control, and all offer a range of convenient pre-programmed HVAC functions.