The Micromaster 420 series, or also called the Micromaster 420s, are devices representing several models of frequency inverters with which you can control the speed of AC motors which have three phases. When we say several models, we don’t think about several different looking devices, no, the only difference is their range which can wary from a 120 W single phase input up to a three phase input which works on 11 kW. It doesn’t matter which one you choose if you are aiming for quality, since these devices are made to last, and with the state of the art IGBT technology, they are no match for competitors. A reliable device with versatile functions and a special pulse-width modulation operation.
With its default settings, the device can work wonders for people who really need them, but if you would like to handle it with more knowledge, then you should definitely look up the Siemens Micromaster 420 Manual, which can be found on ShareDF, the only reliable source of free user manuals on the web: http://sharedf.com/documentation/siemens-micromaster-420-user-manual-in-pdf/