0
\$\begingroup\$

Is it possible to measure the output of a Variable Frequency Drive without relying on it's display data? I tried to measure the line voltage with a DMM and current with a clamp meter but it shows inaccurate results. I'm running the motor at 50Hz and the carrier frequency is 6kHz if that matters.

Thank you in advance!

\$\endgroup\$
0
\$\begingroup\$

Not so easily. It's a really "dirty" signal if you look at it on an oscilloscope. You would need something like a power meter with fairly wide bandwidth, and to measure both current and voltage together (ie. simultaneous samples at a high sample rate, likely with anti-aliasing) and the meter would have to multiply and integrate the result .

Such meters certainly exist, but maybe they are not so affordable.

\$\endgroup\$
0
\$\begingroup\$

Most VFDs can provide analog output signals that are proportional to output current and speed. Output voltage is approximately proportional to speed. The VFD may also be able to provide a signal that is proportional to torque. The VFD signals will be more accurate than any measurement that you can do easily and inexpensively.

If you have a specific reason for wanting the measurements, it might to describe what you are trying to do.

\$\endgroup\$
  • \$\begingroup\$ Sometimes I'm experiencing a voltage drop at high loads (within the limit of course) and the VFD trips showing under-voltage fault. When I measure the input from the mains at such loads it never drops below 210V so I wanted to check the output without trusting the VFD but it looks like I don't have many options on that one. Anyways I will be opening a new question/topic regarding this issue so we don't expand here. \$\endgroup\$ – Ivan P. Jun 7 '18 at 9:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.