VFD output

Discussion in 'General Electronics Chat' started by kevco, Nov 14, 2009.

  1. kevco

    Thread Starter New Member

    Sep 24, 2009

    What is the best setup (hook up) to measure the output of a varable speed drive with a Fluke Scopemeter?


  2. BillB3857

    AAC Fanatic!

    Feb 28, 2009
    One of the problems with measuring the output of VFDs is to find an appropriate reference. Some drives use true Bi-Polar power to drive the H-Bridges and in that case, the common line between the two supplies is ground referenced and you could simply probe any of the output lines referenced to ground.
    Some other drives simply rectify the incoming AC line and send that rectified output to the power rails of the H-Bridges. In that case, the only way I can think of to safely look at the output would be to use 2 channel differential. (Chan A on U, Invert Chan B and tie to V or W. That would give a phase to phase waveform on you scope.