On 10/13/21 1:16 AM, whit3rd wrote:> On Tuesday, October 12, 2021 at 10:04:57 PM UTC-7, palli...@gmail.com wrote: >> whit3rd wrote: >> =============== >> Joerg wrote: >>> ... >>>> What I find strange is that such small VF drives are available for 230V >>>> but not for 120V. >>> >>> >>> Either use an inductive-rated dimmer and universal (with brushes) motor (drill >>> motor, or other handheld power tool), or grab a DC supply suitable for >>> a stepper motor... > >> ** The OP needs an all metal, AC fan cos of the hot environment. >> ** BLDC fans are out - read ALL the posts in a thread sometime. > > The 'BL' in BLDC is for brushless, which isn't the suggestion. >> >> A Variac is all he needs for speed control. > > That's not speed control for induction motors, ...It's not ideal and causes hum at lower rpm but it does work. Did that many years until I hung a UPS up front a few days ago.> ... though, only universal or rectifier-to-DC types, with > brushes... and a triac (like the speed control on a Dremel tool) is cheaper. >I have an inductive-rated dimmer up front which came with the previous set of fans and worked. However, those fans had a plastic frame and that inevitably failed in the hot environment. The mfg thought it was ok but it wasn't. So I replaced them with high-end Papst all-metal AC fans and those stall out between the 40% and 80% settings. Which is why I used a variac from then on. Phil suggested it could be residual DC but I measured it with a lowpass and the UPS doesn't have a DC offset. -- Regards, Joerg http://www.analogconsultants.com/
Small single-phase VFD for 120V?
Started by ●October 12, 2021
Reply by ●October 13, 20212021-10-13
Reply by ●October 13, 20212021-10-13
On 10/13/21 7:54 AM, Joe Gwinn wrote:> On Tue, 12 Oct 2021 16:12:58 -0700 (PDT), Phil Allison > <pallison49@gmail.com> wrote: > >> Joe Gwinn wrote: >> ================ >> >>> It's best to get a small 3-phase motor for this. >> >> ** Giant HUH ??? >> >>> VFDs really do not >>> like their motor circuit opening and closing, as with a centrifugal >>> switch. >> >> ** You feeling OK ? > > I'm OK. The issue is that while VFDs intended for machine tools may > be able to drive a single-phase induction motor as well, but it's best > to short or bypass the centrifugal switch if using the start winding > of a single-phase motor. >They might signal a fault and shut down if one or more connections are seen open. Like when you only connect one of the output phases to a load.> >> Or just got no idea what a Papst AC fan is? > > They seem to all be single-phase, with a start winding. >Just shaded-pole motors, usually. A problem with the small drives from Automation Direct is the same all the others I looked at have. Aside from transfering 1-phase to 3-phase even the 120V versions put out 230V max. That's a recipe for magic smoke even if you tell everyone never to go past 50% or program in a limit. https://cdn.automationdirect.com/static/specs/cfw100acdrive.pdf Beats me why this is. There are so many applications for variable speed of smaller induction motors. Such as heated water circulation, cooling systems et cetera that only need small motors to overcome a miniscule gravity load. They are single-phase and run on regular mains voltage. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●October 13, 20212021-10-13
On Wed, 13 Oct 2021 11:35:07 -0700, Joerg <news@analogconsultants.com> wrote:>On 10/12/21 4:52 PM, John Larkin wrote: >> On Tue, 12 Oct 2021 14:24:31 -0700, Joerg <news@analogconsultants.com> >> wrote: >> >>> On 10/12/21 2:13 PM, John Larkin wrote: >>>> On Tue, 12 Oct 2021 11:19:41 -0700, Joerg <news@analogconsultants.com> >>>> wrote: >>>> >>>>> On 10/12/21 10:29 AM, John Larkin wrote: >>>>>> On Tue, 12 Oct 2021 09:55:29 -0700, Joerg <news@analogconsultants.com> >>>>>> wrote: >>>>>> >>>>>>> Looking for a "better dimmer" to speed-control two small AC fans. They >>>>>>> do not seem to like any kind of dimmer, fan-rated or not. What happens >>>>>>> is that they stall out and start "speed-pumping" in the 40-80% range. >>>>>>> The old ones did fine but the new fancy ones from Papst don't. >>>>>>> >>>>>>> Even when typing in "VFD 120V single phase" all I get as results are >>>>>>> three-phase and mostly for 220V. I am looking for something simple in >>>>>>> the $50-100 range that doesn't have to deliver more than 100W but should >>>>>>> vary the frequency, ideally in a frequency-voltage ratio that I can >>>>>>> tweak with a potmeter. Simple knob to change the speed, ideally not some >>>>>>> menu-driven panel. >>>>>>> >>>>>>> Of course I know how to build that or hack a camping inverter but I >>>>>>> don't want yet another project. Modified sine would probably be good >>>>>>> enough and I can filter that. >>>>>> >>>>>> Do you think frequency control will work on those fan motors? They may >>>>>> be some modern electronic things. >>>>>> >>>>> >>>>> These are traditional AC fan motors sans electronics. They work >>>>> acceptably though not ideal with a variable transformer but the UPS up >>>>> front does not like the variable transformer for some reason (overload >>>>> shutdown). >>>> >>>> Do you need full range control? You could get two speeds with a series >>>> R or C, or even putting fans in series. >>>> >>> >>> In theory yes and I thought about it. However, I need at least four >>> speeds and that really gets old when you have to cram a bunch of big >>> caps into a box. All of which have to be 120V AC rated. Resistors would >>> becomes very toasty and for whatever reason the UPS does not like inductors. >>> >>> I was looking for something that can dial in a speed via a potmeter. >>> What I find strange is that such small VF drives are available for 230V >>> but not for 120V. >>> >>> >>>> I'm doing a fan speed controller right now, but with 24 VDC fans, >>>> driven by a DAC and an opamp. Planning to adjust fan speed based on >>>> box internal temperature. >>>> >>>> We'll have a DAC value integer with low and high limits. Once every >>>> second, if the temp is below setpoint, tick down, and vice versa. That >>>> is a low-drama control loop. >>>> >>> >>> With a meaningful hysteresis that should indeed be low-drama. >> >> No hysteresis. It's a 1-LSB bang-bang loop. >> > >Then the hysteresis is one LBS :-)I guess so. It never settles down. It's a really cool algorithmn. It starts up with the fans barely turning, basically silent, and never does anything acoustically dramatic. -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon
Reply by ●October 13, 20212021-10-13
whit3rd - colossal fuckwit wrote: =======================> > > ... > > > > What I find strange is that such small VF drives are available for 230V > > > > but not for 120V. > > > > > > Either use an inductive-rated dimmer and universal (with brushes) motor (drill > > > motor, or other handheld power tool), or grab a DC supply suitable for > > > a stepper motor... > > > ** The OP needs an all metal, AC fan cos of the hot environment. > > ** BLDC fans are out - read ALL the posts in a thread sometime. > > The 'BL' in BLDC is for brushless, which isn't the suggestion.** FFS - there is no relevant suggestion here at all.> > A Variac is all he needs for speed control. > > That's not speed control for induction motors,** Yes it is you fucking, know nothing twat.. Standard home fans can be speed controlled over the *full range* using one - way better than with the built in speed switch. Same goes for common, square frame AC axial fans and the like. FOAD you moron. ...... Phil
Reply by ●October 13, 20212021-10-13
Joe Gwinn wrote:>> > > > >** You feeling OK ? > I'm OK. The issue is that while VFDs intended for machine tools may > be able to drive a single-phase induction motor as well, but it's best > to short or bypass the centrifugal switch if using the start winding > of a single-phase motor. > >Or just got no idea what a Papst AC fan is? > > They seem to all be single-phase, with a start winding. >** You on drugs ? Take a fucking look at one. ..... Phil
Reply by ●October 13, 20212021-10-13
Joerg wrote: ==============> These are traditional AC fan motors sans electronics. They work > acceptably though not ideal** Why post drivel like that? " not ideal" = what ??? And how do you know? Being deliberately vague does not make you sound intelligent - it's fucking stupid. .... Phil
Reply by ●October 13, 20212021-10-13
Joerg wrote: ==========> > > ** FFS - so the real story has nothing to do with fan speed control ????? > > > It does. The variac was never that great, fans become a bit louder at > lower speeds.** That is total BULLSHIT !!! Domestic and AC equipment fans run silently at low settings on a Variac. ..... Phil
Reply by ●October 13, 20212021-10-13
Joerg wrote: =========== re: using a Variac:> > > > That's not speed control for induction motors, ... > > It's not ideal and causes hum at lower rpm** Bullshit !!!!> Phil suggested it could be residual DC but I measured it with a lowpass > and the UPS doesn't have a DC offset.** Monitor the AC current in the Variac primary. Bet you see a different story. ..... Phil
Reply by ●October 13, 20212021-10-13
Joerg <news@analogconsultants.com> wrote:> On 10/12/21 10:51 AM, Cydrome Leader wrote: >> Joerg <news@analogconsultants.com> wrote: >>> Looking for a "better dimmer" to speed-control two small AC fans. They >>> do not seem to like any kind of dimmer, fan-rated or not. What happens >>> is that they stall out and start "speed-pumping" in the 40-80% range. >>> The old ones did fine but the new fancy ones from Papst don't. >> >> Sounds like you're not dealing with a plain AC fan motor anymore. Papst >> the cooling fan maker? > > > Yes, that company. They are plain AC motors, IIRC the shaded-pole kind. > > >> ... just change to a DC fan with speed control. VFDs on >> small motors is completly pointless anyways. >> > > This is a bit more challenging. The fans are in an environment that's > too hot for electronics, which is also why they are completely metal.How many speeds do you need? I've never seen a weird speed pumping or racing issue with a decent speed controller (not a light dimmer, those are garbage, always) on even crap fan motors. They mighy run loud, or over heat at lowspeeds, or close to stall but that's about it. The Dart Controls 55AC series is as good as it gets for a triac based speed controller. Built well, handles high currents, easy to fix and sometimes real cheap on ebay- https://www.dart-controls.com/category-s/162.htm
Reply by ●October 13, 20212021-10-13
Cydrome Leader <presence@mungepanix.com> wrote:> Joerg <news@analogconsultants.com> wrote: >> On 10/12/21 10:51 AM, Cydrome Leader wrote: >>> Joerg <news@analogconsultants.com> wrote: >>>> Looking for a "better dimmer" to speed-control two small AC fans. They >>>> do not seem to like any kind of dimmer, fan-rated or not. What happens >>>> is that they stall out and start "speed-pumping" in the 40-80% range. >>>> The old ones did fine but the new fancy ones from Papst don't. >>> >>> Sounds like you're not dealing with a plain AC fan motor anymore. Papst >>> the cooling fan maker? >> >> >> Yes, that company. They are plain AC motors, IIRC the shaded-pole kind. >> >> >>> ... just change to a DC fan with speed control. VFDs on >>> small motors is completly pointless anyways. >>> >> >> This is a bit more challenging. The fans are in an environment that's >> too hot for electronics, which is also why they are completely metal. > > How many speeds do you need? I've never seen a weird speed pumping or > racing issue with a decent speed controller (not a light dimmer, those are > garbage, always) on even crap fan motors. They mighy run loud, or over > heat at lowspeeds, or close to stall but that's about it. > > The Dart Controls 55AC series is as good as it gets for a triac based > speed controller. Built well, handles high currents, easy to fix and > sometimes real cheap on ebay- > > https://www.dart-controls.com/category-s/162.htmscratch that bogus URL. The manufacturer is https://www.dartcontrols.com/products/55ac-triac-ac-motor-speed-control/
