Cable Motor Filters
Long cables to PWM motors create ringing, waveform distortion, and other artifacts of pulsed drive signals causing malfunction of motors. Special cable motor filters help to mitigate these problems.
Cable motor filter DH231 is designed for and was approved by Danfoss for operation with Danfoss stepper motor - based valves. It is a direct replacement for an obsolete AKA 211 filter.
Install and connect DH231 according to Danfoss instructions. The basic diagram is shown here.