ELC 117- VFD & Motor wired and programmed by Nathan Piercy and Luke Matthews

Shows comparison of Fluke 1587 multimeter with "low pass" filter and the Fluke Scopemeter. The 1587 gives true RMS readings of the 60 Hertz fundamental frequency because it filters or blocks the harmonics that are present in VFD outputs (pulse width modulated) The Scopemeter has wide bandwidth of 20 Mhz (megahertz)
so it calculates the harmonics. The Scope simply gives us the waveform vi
ew and correct frequency value. We get our correct voltage reading from the Fluke 1587.
Thanks for watching, Durwood King, Instructor, Sampson Community College

[@danielardelian2]

The Fluke "123" does not have a low-pass filter but it does have a "Vpwm" measurement option exactly for this purpose (to measure PWM-generated voltage).
The newer "123B", with color display, has a 10 KHz low-pass filter that can be enabled from the menu.

[@tonys9391]

How do you connect the scope probe to the motor? Reference lead to the ground or to the phase?

[@durwoodking9696]

Phase to phase. Fluke Scope meter 123 can handle 460 vac