Fluke DMMs and VFD motor drives
 

DaveC wrote:
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

A scope meter is the best tool for such a job..

Fluke DMMs and VFD motor drives
 

A scope meter is the best tool for such a job..
[Jamie]

Why?

Also, I already have a hand-held scope (Tektronix) so I don't want to spend
$$ unnecessarily on features I already have in maybe another tool.

Dave

Fluke DMMs and VFD motor drives
 

DaveC wrote:

A scope meter is the best tool for such a job..

[Jamie]

Why?

Also, I already have a hand-held scope (Tektronix) so I don't want to spend
$$ unnecessarily on features I already have in maybe another tool.

Dave

Because working with VFD's, especially with Vector mode drives, You see
a lot more happening in the output over what a DMM can show you.

Even my Fluke 289 with it's low pass will give incorrect readings of
what is really happening if a Vector drive isn't tuned, incorrect
induction values, defective encoder, something etc..

If all you're looking for is a ball park figure, then I guess you could
use a low pass DMM.

It's up to you.

For every man, they have their own tool!