VFD Motor ringing


Not too far OT as this is a lathe motor.

Yaskawa 606 PC3 VFD 240V/3ph AC in & out driving a Baldor 5hp inverter-rated CNC lathe motor.

Had the inverter rebuilt, new caps, reinstalled and works fine, but now the motor rings on deceleration.

It does have a braking resistor in the circuit.

Cable from VFD to motor is short, under one meter in length.

I do have the PC3 manual, and I have studied it. It gets a bit complex for me in some chapters ;-)

I'm assuming that a decel-time parameter was reset. That, or I need to use an S-curve decel? Any ideas what parameter to play with and which way it needs to go?

In general, what's up with a 3ph AC motor on a short cable ringing?

Thanks for any thoughts.

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PCS fired this volley in news:76cc86cc-69e1-4697- snipped-for-privacy@googlegroups.com:

Does it ring at all speeds, or only when accelerating and decelerating?

I _don't_ have the PC3 manual, but if there's a setting for the chopping frequency, that might change things. You might have just gotten lucky and found a motor the windings of which resonate at exactly the chopping rate of the VFD, as set up.

Although the put out a "sine wave" (sort of), there are steps in it that can cause windings to ring.


Reply to
Lloyd E. Sponenburgh

I had the same problem on my bin dump water pump...

Folks told me to try carrier frequnecy change. it didn't work. i had to remove the VFD


Reply to
Karl Townsend

Thanks for the question.

Lathe had been working fine for years, VFD went down, voltage fault indicat ed. I had it professionally rebuilt. They may have reset the constants duri ng rebuild.

I had not saved the parameter settings, as I had no way to read them, VFD o nly had an indicator panel fitted. Now I have gotten hold of a Programming panel to replace the indicator panel (A JVOP-114 for the PC3) so I can now read and set the parameters/constants with this new input & output program ming panel.

Motor rings when spindle stop is commanded from the CNC's control. The mo tor speed is controlled remotely by the CNC, not manually from the VFD's pa nel. Only rings on spindle stop. Spindle stops in seconds. Must be plent y of energy to dump into the braking resistor. Suspect the decel time param eter needs adjustment? Or...?

Hope that's clear.

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PCS fired this volley in news: snipped-for-privacy@googlegroups.com:

Yep. Even the braking current is switched (rapidly) in order to obey the deceleration profile.

Check the switching frequency. There might even be a separate one for the braking circuit.


Reply to
Lloyd E. Sponenburgh


To follow up; what worked in my case was to adjust the frequency lower limit, constant #25, to a value of 10%. This changed the frequency profile and stopped the motor ringing for my particular application.

Hope that helps.

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