Fluke DMMs and VFD motor drives

I'm considering the purchase of a new Fluke DMM. I like the low-impedance feature of the 117, but the low-pass filter feature of the 87 is also
attractive.
I had a conversation with a support engineer at Fluke today to try to help me decide between these two meters.
It came down to the question of whether the variable-frequency drives I come across will have noisy outputs which the low-pass filter will be helpful in dealing with.
Among other services, I install some (3-phase, mostly) VFDs for 230v motors on old printing equipment to give them a 2nd life.
I have no idea how many (ie, percentage) of VFDs are "noisy" that will make measurement difficult with a DMM w/o low-pass filtering. Is this a common problem?
If you've got some experience in this area I'd like to hear your comments.
Thanks, Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
DaveC wrote:

The Fluke 289 has both a low pass filter and LowZ input impedance. But you get the annoyance of the short battery life and graphical display. http://us.fluke.com/usen/Products/Fluke+289.htm
Check out the new Fluke 28-II rugged meter, it also has the filter, but no lowZ: http://us.fluke.com/usen/Products/Fluke+27+II+28+II.htm
Quote: "Unique function for accurate voltage and frequency measurements on adjustable speed motor drives and other electrically noisy equipment (28 II)" but that is just the normal low pass filter feature.
Dave.
--
================================================
Check out my Electronics Engineering Video Blog & Podcast:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jon Slaughter wrote:

Modding a meter can potentially make it unsafe, so not a good idea to recommend. The Fluke 289 has both features, so no need to bodge it.
Dave.
--
================================================
Check out my Electronics Engineering Video Blog & Podcast:
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
David L. Jones wrote:

I use my 289 as a clock since I don't have a clock in most places I am at, except my desk or bench. I can't wear watches.
P.S. I wish it was a little faster in response.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

FYI, the Fluke 43 PQAs on campus show the whole mess of PWM up at 15kHz or whatever they run them at. I forget the VFD type in the lab, but obviously it produces a PWM ("noisy"?) output. It still reads correctly, as far as I know (RMS, power factor, ...).
Tim
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.