Hi,

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.

--
PaulS

PCS fired this volley in news:76cc86cc-69e1-4697-
:

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

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.

Lloyd

On Wednesday, June 4, 2014 2:45:36 PM UTC-4, Lloyd E. Sponenburgh wrote:
PCS fired this volley in news:76cc86cc-69e1-4697-

:



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



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.



Lloyd

Thanks for the question.

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

I had not saved the parameter settings, as I had no way to read them, VFD only 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 programming panel.

Motor rings when spindle stop is commanded from the CNC's control. The motor speed is controlled remotely by the CNC, not manually from the VFD's panel. Only rings on spindle stop. Spindle stops in seconds. Must be plenty of energy to dump into the braking resistor. Suspect the decel time parameter needs adjustment? Or...?

Hope that's clear.

--
PaulS

PCS fired this volley in
:

Motor rings when spindle stop is commanded from the CNC's control.
The motor speed is controlled remotely by the CNC, not manually from
the VFD's panel. Only rings on spindle stop. Spindle stops in
seconds. Must be plenty of energy to dump into the braking resistor.
Suspect the decel time parameter needs adjustment? Or...?

Hope that's clear.

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.

LLoyd

On Wed, 04 Jun 2014 14:48:47 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

PCS fired this volley in
:

Motor rings when spindle stop is commanded from the CNC's control.
The motor speed is controlled remotely by the CNC, not manually from
the VFD's panel. Only rings on spindle stop. Spindle stops in
seconds. Must be plenty of energy to dump into the braking resistor.
Suspect the decel time parameter needs adjustment? Or...?

Hope that's clear.

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.

LLoyd

There is. And IRRC..there is one to change the working frequency of
the breaking power.


"Libertarianism IS fascism... Fascism is corporate government – a Libertarian’s wet dream"
Tala Brandeis
Owner at Tala Brandeis Associates"

On Wed, 4 Jun 2014 11:40:31 -0700 (PDT), PCS
wrote:

Hi,

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.

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

karl

On Wed, 4 Jun 2014 11:40:31 -0700 (PDT), PCS
wrote:

Hi,

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.

Where did you have your PC3 rebuilt at? I have one running my Gorton
Mastermill that needs fixed.


"Libertarianism IS fascism... Fascism is corporate government – a Libertarian’s wet dream"
Tala Brandeis
Owner at Tala Brandeis Associates"

On Wednesday, June 4, 2014 2:40:31 PM UTC-4, PCS wrote:
Hi,



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.



--

PaulS

Hi,

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.

--
PaulS