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Guest

Fri Sep 28, 2018 7:45 pm   



Last time I looked, which was several years ago and for a different
reason, I found nothing. Today I found them and they are cheap. I
shoulda looked before posting.
Sorry,
Eric

default
Guest

Fri Sep 28, 2018 9:50 pm   



On Fri, 28 Sep 2018 11:27:15 -0700, etpm_at_whidbey.com wrote:

Quote:
Last time I looked, which was several years ago and for a different
reason, I found nothing. Today I found them and they are cheap. I
shoulda looked before posting.
Sorry,
Eric


I thought you wanted to keep the old motors? Motors with capacitors
don't lend themselves to VFD.

Sjouke Burry
Guest

Fri Sep 28, 2018 11:45 pm   



On 28-9-2018 21:50, default wrote:
Quote:
On Fri, 28 Sep 2018 11:27:15 -0700, etpm_at_whidbey.com wrote:

Last time I looked, which was several years ago and for a different
reason, I found nothing. Today I found them and they are cheap. I
shoulda looked before posting.
Sorry,
Eric

I thought you wanted to keep the old motors? Motors with capacitors
don't lend themselves to VFD.

No.But if you feed them two power sources with a 90 degree
phase shift, you dont need a cap , and you CAN control the speed.


Guest

Sat Sep 29, 2018 1:45 am   



On Fri, 28 Sep 2018 15:50:54 -0400, default <default_at_defaulter.net>
wrote:

Quote:
On Fri, 28 Sep 2018 11:27:15 -0700, etpm_at_whidbey.com wrote:

Last time I looked, which was several years ago and for a different
reason, I found nothing. Today I found them and they are cheap. I
shoulda looked before posting.
Sorry,
Eric

I thought you wanted to keep the old motors? Motors with capacitors
don't lend themselves to VFD.

Please see the link:
https://www.ato.com/1-2hp-vfd-single-phase-input-output
The link says nothing about cap run motors. What happens if the run
cap is left in circuit?
THanks,
Eric

Jasen Betts
Guest

Sat Sep 29, 2018 3:33 am   



On 2018-09-29, etpm_at_whidbey.com <etpm_at_whidbey.com> wrote:
Quote:
On Fri, 28 Sep 2018 15:50:54 -0400, default <default_at_defaulter.net
wrote:

On Fri, 28 Sep 2018 11:27:15 -0700, etpm_at_whidbey.com wrote:

Last time I looked, which was several years ago and for a different
reason, I found nothing. Today I found them and they are cheap. I
shoulda looked before posting.
Sorry,
Eric

I thought you wanted to keep the old motors? Motors with capacitors
don't lend themselves to VFD.
Please see the link:
https://www.ato.com/1-2hp-vfd-single-phase-input-output
The link says nothing about cap run motors. What happens if the run
cap is left in circuit?
THanks,


Capacitor run motors use the capacitor to shift the phase of the
current applied to one of the windings.

this phase shift is both load and frequency dependant so you get low
starting torque (due to rediuced phase shift) and if you reduce the
drive frequency you'll also get reduced pahse shift and thus reduced
torque.

--
ت


Guest

Sat Sep 29, 2018 5:45 pm   



On Sat, 29 Sep 2018 01:33:43 -0000 (UTC), Jasen Betts
<jasen_at_xnet.co.nz> wrote:

Quote:
On 2018-09-29, etpm_at_whidbey.com <etpm_at_whidbey.com> wrote:
On Fri, 28 Sep 2018 15:50:54 -0400, default <default_at_defaulter.net
wrote:

On Fri, 28 Sep 2018 11:27:15 -0700, etpm_at_whidbey.com wrote:

Last time I looked, which was several years ago and for a different
reason, I found nothing. Today I found them and they are cheap. I
shoulda looked before posting.
Sorry,
Eric

I thought you wanted to keep the old motors? Motors with capacitors
don't lend themselves to VFD.
Please see the link:
https://www.ato.com/1-2hp-vfd-single-phase-input-output
The link says nothing about cap run motors. What happens if the run
cap is left in circuit?
THanks,

Capacitor run motors use the capacitor to shift the phase of the
current applied to one of the windings.

this phase shift is both load and frequency dependant so you get low
starting torque (due to rediuced phase shift) and if you reduce the
drive frequency you'll also get reduced pahse shift and thus reduced
torque.

I know how cap run only motors work, how they have low starting
torque. What if the frequency is increased? Does that increase
starting torque? I can see the drive starting the motor at 60 Hz or
above and then once up to some certain speed shifting to the
programmed torque.
The description of the drive says that it supplies 1.5 times running
torque for starting torque. Did you follow the link? I don't
understand these drives well, the single phase ones. Do you?
Thanks,
Eric

M Philbrook
Guest

Fri Oct 05, 2018 12:45 am   



In article <us7vqd5a28kd00aha8q79dsc2md35aui86_at_4ax.com>,
etpm_at_whidbey.com says...
Quote:

On Sat, 29 Sep 2018 01:33:43 -0000 (UTC), Jasen Betts
jasen_at_xnet.co.nz> wrote:

On 2018-09-29, etpm_at_whidbey.com <etpm_at_whidbey.com> wrote:
On Fri, 28 Sep 2018 15:50:54 -0400, default <default_at_defaulter.net
wrote:

On Fri, 28 Sep 2018 11:27:15 -0700, etpm_at_whidbey.com wrote:

Last time I looked, which was several years ago and for a different
reason, I found nothing. Today I found them and they are cheap. I
shoulda looked before posting.
Sorry,
Eric

I thought you wanted to keep the old motors? Motors with capacitors
don't lend themselves to VFD.
Please see the link:
https://www.ato.com/1-2hp-vfd-single-phase-input-output
The link says nothing about cap run motors. What happens if the run
cap is left in circuit?
THanks,

Capacitor run motors use the capacitor to shift the phase of the
current applied to one of the windings.

this phase shift is both load and frequency dependant so you get low
starting torque (due to rediuced phase shift) and if you reduce the
drive frequency you'll also get reduced pahse shift and thus reduced
torque.
I know how cap run only motors work, how they have low starting
torque. What if the frequency is increased? Does that increase
starting torque? I can see the drive starting the motor at 60 Hz or
above and then once up to some certain speed shifting to the
programmed torque.
The description of the drive says that it supplies 1.5 times running
torque for starting torque. Did you follow the link? I don't
understand these drives well, the single phase ones. Do you?
Thanks,
Eric


Torque on the bottom end for AC motors of such type requires a
constant DC current to be in the mix called magnetic current. This
current needs to be around 35% of the full current of the motor for good
slow RPM operations and torque at the bottom end.

You would do better if you can get your hands on a 3 phase motor, a
small one and then get an inverter that operates from single phase that
has the VECTOR mode in it. With VECTOR mode you can program minimum
current that gives you a stable low RPM and some torque. You also want
to make sure the motor is rated for an inverter, one that is designed to
operate at any RPM with woudings that are fit for the PWM mode..

Of course, you could simply use a miniature PIV gear, the V-Belt style
for simplicity.

Jamie

default
Guest

Fri Oct 05, 2018 11:45 am   



On Sat, 29 Sep 2018 08:57:16 -0700, etpm_at_whidbey.com wrote:

Quote:
On Sat, 29 Sep 2018 01:33:43 -0000 (UTC), Jasen Betts
jasen_at_xnet.co.nz> wrote:

On 2018-09-29, etpm_at_whidbey.com <etpm_at_whidbey.com> wrote:
On Fri, 28 Sep 2018 15:50:54 -0400, default <default_at_defaulter.net
wrote:

On Fri, 28 Sep 2018 11:27:15 -0700, etpm_at_whidbey.com wrote:

Last time I looked, which was several years ago and for a different
reason, I found nothing. Today I found them and they are cheap. I
shoulda looked before posting.
Sorry,
Eric

I thought you wanted to keep the old motors? Motors with capacitors
don't lend themselves to VFD.
Please see the link:
https://www.ato.com/1-2hp-vfd-single-phase-input-output
The link says nothing about cap run motors. What happens if the run
cap is left in circuit?
THanks,

Capacitor run motors use the capacitor to shift the phase of the
current applied to one of the windings.

this phase shift is both load and frequency dependant so you get low
starting torque (due to rediuced phase shift) and if you reduce the
drive frequency you'll also get reduced pahse shift and thus reduced
torque.
I know how cap run only motors work, how they have low starting
torque. What if the frequency is increased? Does that increase
starting torque? I can see the drive starting the motor at 60 Hz or
above and then once up to some certain speed shifting to the
programmed torque.
The description of the drive says that it supplies 1.5 times running
torque for starting torque. Did you follow the link? I don't
understand these drives well, the single phase ones. Do you?
Thanks,
Eric


Increasing frequency increases the speed not the torque. Overall
power increases since it is a factor of speed and torque.

The 90 degree phase shift is frequency dependent the capacitance and
inductance of the winding will only shift 90 degrees at one frequency.

All the VFD's I've used have three phase where each output has a
voltage that's 120 degrees phase shifted from the others. If there is
a 90 degree VFD I haven't encountered it (but haven't looked either)
It would require rewiring the motor and removing the cap but that's
not impossible....

check out:
http://www.invertekdrives.com/variable-speed-drives/optidrive-e2-single-phase/

default
Guest

Fri Oct 05, 2018 11:45 am   



On Sat, 29 Sep 2018 08:57:16 -0700, etpm_at_whidbey.com wrote:

Quote:
On Sat, 29 Sep 2018 01:33:43 -0000 (UTC), Jasen Betts
jasen_at_xnet.co.nz> wrote:

On 2018-09-29, etpm_at_whidbey.com <etpm_at_whidbey.com> wrote:
On Fri, 28 Sep 2018 15:50:54 -0400, default <default_at_defaulter.net
wrote:

On Fri, 28 Sep 2018 11:27:15 -0700, etpm_at_whidbey.com wrote:

Last time I looked, which was several years ago and for a different
reason, I found nothing. Today I found them and they are cheap. I
shoulda looked before posting.
Sorry,
Eric

I thought you wanted to keep the old motors? Motors with capacitors
don't lend themselves to VFD.
Please see the link:
https://www.ato.com/1-2hp-vfd-single-phase-input-output
The link says nothing about cap run motors. What happens if the run
cap is left in circuit?
THanks,

Capacitor run motors use the capacitor to shift the phase of the
current applied to one of the windings.

this phase shift is both load and frequency dependant so you get low
starting torque (due to rediuced phase shift) and if you reduce the
drive frequency you'll also get reduced pahse shift and thus reduced
torque.
I know how cap run only motors work, how they have low starting
torque. What if the frequency is increased? Does that increase
starting torque? I can see the drive starting the motor at 60 Hz or
above and then once up to some certain speed shifting to the
programmed torque.
The description of the drive says that it supplies 1.5 times running
torque for starting torque. Did you follow the link? I don't
understand these drives well, the single phase ones. Do you?
Thanks,
Eric


http://ww1.microchip.com/downloads/en/AppNotes/AC%20Induction%20Motor%2000984a.pdf

Microchip component that can be programmed for 2 phase operation if
you wanted to build such a device - the application note also
discusses speed torque etc..


Guest

Fri Oct 05, 2018 6:45 pm   



On Fri, 05 Oct 2018 06:40:52 -0400, default <default_at_defaulter.net>
wrote:

Quote:
On Sat, 29 Sep 2018 08:57:16 -0700, etpm_at_whidbey.com wrote:

On Sat, 29 Sep 2018 01:33:43 -0000 (UTC), Jasen Betts
jasen_at_xnet.co.nz> wrote:

On 2018-09-29, etpm_at_whidbey.com <etpm_at_whidbey.com> wrote:
On Fri, 28 Sep 2018 15:50:54 -0400, default <default_at_defaulter.net
wrote:

On Fri, 28 Sep 2018 11:27:15 -0700, etpm_at_whidbey.com wrote:

Last time I looked, which was several years ago and for a different
reason, I found nothing. Today I found them and they are cheap. I
shoulda looked before posting.
Sorry,
Eric

I thought you wanted to keep the old motors? Motors with capacitors
don't lend themselves to VFD.
Please see the link:
https://www.ato.com/1-2hp-vfd-single-phase-input-output
The link says nothing about cap run motors. What happens if the run
cap is left in circuit?
THanks,

Capacitor run motors use the capacitor to shift the phase of the
current applied to one of the windings.

this phase shift is both load and frequency dependant so you get low
starting torque (due to rediuced phase shift) and if you reduce the
drive frequency you'll also get reduced pahse shift and thus reduced
torque.
I know how cap run only motors work, how they have low starting
torque. What if the frequency is increased? Does that increase
starting torque? I can see the drive starting the motor at 60 Hz or
above and then once up to some certain speed shifting to the
programmed torque.
The description of the drive says that it supplies 1.5 times running
torque for starting torque. Did you follow the link? I don't
understand these drives well, the single phase ones. Do you?
Thanks,
Eric

http://ww1.microchip.com/downloads/en/AppNotes/AC%20Induction%20Motor%2000984a.pdf

Microchip component that can be programmed for 2 phase operation if
you wanted to build such a device - the application note also
discusses speed torque etc..

The site I posted a link to is a typical Chinese to English translated
site. But I was able to find two circuits on the site for cap start as
well as cap run motors. I was not able to find any other single phase
VFD makes that offered these circuits. Anyway, I'm gonna buy one of
the things because they say it will work on the motor in question.
I'll try it in my shop first on both type motors. Since it turns out
the customer's motor is a cap start motor the centrifugal start switch
will need to be bypassed if the motor is to be operated below 60 Hz.
But I think instead I will set it up to go from 60 to 90 Hz. That
should be enough speed differential to bridge between the existing
speed selections.
Eric

elektroda.net NewsGroups Forum Index - Electronic for beginners - Single phase VFD-nevermind

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