The John Doe troll stated the following in message-id <sdhn7c$pkp$4@dont-email.me>:> The troll doesn't even know how to format a USENET post...And the John Doe troll stated the following in message-id <sg3kr7$qt5$1@dont-email.me>:> The reason Bozo cannot figure out how to get Google to keep from > breaking its lines in inappropriate places is because Bozo is > CLUELESS...And yet, the clueless John Doe troll has itself posted yet another incorrectly formatted USENET posting on Thu, 14 Oct 2021 16:33:25 -0000 (UTC) in message-id <sk9m4k$qvd$1@dont-email.me>. hLmVojKSMWXl
Small single-phase VFD for 120V?
Started by ●October 12, 2021
Reply by ●October 14, 20212021-10-14
Reply by ●October 14, 20212021-10-14
On 2021-10-14, Joe Gwinn <joegwinn@comcast.net> wrote:> On Thu, 14 Oct 2021 09:30:59 -0700, Joerg <news@analogconsultants.com> > wrote: > >>On 10/14/21 7:52 AM, Joe Gwinn wrote: >>> On Wed, 13 Oct 2021 11:51:07 -0700, Joerg <news@analogconsultants.com> >>> wrote: >>> >>>> 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. >>> >>> True. Some VFDs allow one to program to disable that fault. >>> >> >>Ah, that may be an option. The other job would be to make 110% sure that >>it can never go past 120V because most VFDs put out 230V max, even those >>for 120V input. >> >>> >>>>> >>>>>> 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. >>> >>> The main application for 120 Vac single phase in to 220 Vac three >>> phase in small sizes is to allow three-phase industrial machines to be >>> run from US domestic single-phase power. Three-phase 220 Vac >>> industrial equipment is cheap and plentiful on the used market in the >>> US. >>> >>> One common use is bench grinders and sanders and drill presses, where >>> the variable speed is an added big advantage. One sees a lot of these >>> machines on Craigs List. >>> >> >>Yes, that may be the reaon. Probably not enough market for driving 120V >>motors. >> >> >>> One can also get three-phase fans and circulation pumps, which are >>> intended to be driven by a VFD which is commanded by some kind of PID >>> (Proportional Integral Derivative) temperature controller, versus the >>> more common bang-bang controller. >>> >> >>This situation requires the small muffin-style fans. > > I would hazard that you will need a DC fan for proportional control. > > If I recall, the speed controls in overhead fans (with 4-foot sweep > diameter, consist of switched AC motor capacitors in series with the > motor. I don't recall if I wrote the details down, but this was how > the Hunter fan in one room in my house works. There are likely some > patents on such. There are lots of circuits on the web. The > underlying motor has two windings, and is not shaded pole.ceiling fans are often capacitor run as this setup provides an easy way to reverse them. (reversing a shaded pole motor is harder) the series capacitor just makes a current limit reducing the torque and thus the speed. if you unbolt the blades you'll see that they always run at the same speed unloaded.> I suppose that for a shaded-pole induction motor in fan duty, a small > variac would work, but would be a bit clumsy Maybe a tapped > transformer.capacitor should work too. -- Jasen.
Reply by ●October 14, 20212021-10-14
On Thursday, October 14, 2021 at 4:07:53 AM UTC-7, palli...@gmail.com wrote:> Cunthead, know nothing FUCKING arsehole Bill Slowman bullshitted . > ========================================================= > > > > > > > > > > Perhaps, but to burn the motor takes a lot of power and surely running > > > > > > > > the motor from a variac at reduced voltage reduces the liklihood of heat > > > > > > > > damage? > > > > > > > > > > > > > ** Motor current drops in line with applied AC voltage. > > > > > > > > > > > No, of course it doesn't; > ** Fraid it actually *does* with fan motors. ...Empirical knowledge of 'fan motors' doesn't relate to the class of AC induction motors. A well-designed induction motor has windings IN THE ROTOR which are short circuited, and good (near 100%) flux coupling from driven stator to that rotor. That's a motor with lots of torque, which dims the lights when started, and many horsepower-per-pound, at high energy efficiency. That motor is, if the rotor is not following the AC frequency, a transformer from an AC input to short-circuited windings (in the rotor). Voltage squared over R becomes a divide-by-zero problem if you stall the motor.> > > I have a common 40W pedestal fan with a 13 inch dia fan blade. > > > Tested a few minutes ago: > > > > > > At 240VAC rms current is 163mA. > > > at 200VAC it became 144. > > > at 100VAC it become 76. > > > at 50VAC it become 33. > > > > > > by which time the blade was no longer turning. > > > Not far off linear, you *must* agree.That's specifically a FAN MOTOR, many of which (and there were sewing machine motors like this too) were very inefficient in their flux coupling so that the slow-down burn-up problem would not be fatal, and so that a rheostat control could be added. Those motors are completely atypical of the induction motor type (indeed, might not be true induction motors at all). A specification for that motor wouldn't include 'thermal protection' of the add-an-extra-part type, and wouldn't have efficiency to brag about either.
Reply by ●October 14, 20212021-10-14
A nym-shifting stalker, usually "Corvid" also "Charger Boy" still sore from being spanked in (sci.electronics.repair)... see also... =?UTF-8?Q?C=c3=b6rvid?= <bl@ckbirds.org> =?UTF-8?B?8J+QriBDb3dzIGFyZSBOaWNlIPCfkK4=?= <nice@cows.moo> Banders <snap@mailchute.com> Covid-19 <always.look@message.header> Corvid <bl@ckbirds.net> Corvid <bl@ckbirds.org> Cows Are Nice <cows@nice.moo> Cows are nice <moo@cows.org> Cows are Nice <nice@cows.moo> dogs <dogs@home.com> Edward H. <dtgamer99@gmail.com> Edward Hernandez <dtgamer99@gmail.com> Great Pumpkin <pumpkin@patch.net> Jose Curvo <jcurvo@mymail.com> Local Favorite <how2recycle@palomar.info> Peter Weiner <dtgamer99@gmail.com> Sea <freshness@coast.org> Standard Poodle <standard@poodle.com> triangles <build@home.com> and others... -- Edward Hernandez <dtgamer99@gmail.com> wrote:> Path: eternal-september.org!reader02.eternal-september.org!feeder1.feed.usenet.farm!feed.usenet.farm!newsfeed.xs4all.nl!newsfeed8.news.xs4all.nl!news-out.netnews.com!news.alt.net!fdc2.netnews.com!peer03.ams1!peer.ams1.xlned.com!news.xlned.com!peer03.ams4!peer.am4.highwinds-media.com!news.highwinds-media.com!fx02.ams4.POSTED!not-for-mail > From: Edward Hernandez <dtgamer99@gmail.com> > Subject: Re: Small single-phase VFD for 120V? > Newsgroups: sci.electronics.design,free.spam > References: <islt03Fdtb9U1@mid.individual.net> <5bhbmgl61ctm1mhlnfmqo9658os1iufmo5@4ax.com> <ism1tuFerkoU1@mid.individual.net> <q8ubmg5cunq14rpqg33lkphirep7u3altr@4ax.com> <ismcohFgt8nU1@mid.individual.net> <d0f5b915-90e5-490c-875a-91bf2a27ff9an@googlegroups.com> <66f8470c-6c50-4101-b9ae-7157a8e93701n@googlegroups.com> <e4c7ad52-5915-4db3-8a3d-cdd56e81ac6cn@googlegroups.com> <de8f4f80-6455-4a58-8756-49c3e21604f1n@googlegroups.com> <89c2dc68-cbfd-449c-8847-a35be5f1a0d6n@googlegroups.com> <sk8iih$clf$1@dont-email.me> <f450c032-de59-4302-bb62-0e80d6c9e158n@googlegroups.com> <dc2978bc-aa95-432c-b95d-3561ed35c7edn@googlegroups.com> <1fea09a0-cbbd-4237-b617-6664a297eb04n@googlegroups.com> <1d79963e-0387-4367-8b88-d882b2e97545n@googlegroups.com> <sk9m4k$qvd$1@dont-email.me> > Lines: 18 > Message-ID: <4z_9J.1112217$E24.1014130@usenetxs.com> > X-Complaints-To: https://www.astraweb.com/aup > NNTP-Posting-Date: Thu, 14 Oct 2021 18:21:52 UTC > Date: Thu, 14 Oct 2021 18:21:52 GMT > X-Received-Bytes: 1870 > Xref: reader02.eternal-september.org sci.electronics.design:649124 free.spam:16141 > > The John Doe troll stated the following in message-id > <sdhn7c$pkp$4@dont-email.me>: > >> The troll doesn't even know how to format a USENET post... > > And the John Doe troll stated the following in message-id > <sg3kr7$qt5$1@dont-email.me>: > >> The reason Bozo cannot figure out how to get Google to keep from >> breaking its lines in inappropriate places is because Bozo is >> CLUELESS... > > And yet, the clueless John Doe troll has itself posted yet another > incorrectly formatted USENET posting on Thu, 14 Oct 2021 16:33:25 -0000 > (UTC) in message-id <sk9m4k$qvd$1@dont-email.me>. > > hLmVojKSMWXl > > >
Reply by ●October 14, 20212021-10-14
whit3rd who needs shooting in the head wrote: ==================================> > > > > > > > > > Perhaps, but to burn the motor takes a lot of power and surely running > > > > > > > > > the motor from a variac at reduced voltage reduces the liklihood of heat > > > > > > > > > damage? > > > > > > > > > > > > > > > ** Motor current drops in line with applied AC voltage. > > > > > > > > > > > > > No, of course it doesn't; > > > ** Fraid it actually *does* with fan motors. ... > > Empirical knowledge of 'fan motors' doesn't relate to the class of AC induction motors. >=============================================================== ** The ** TOPIC* is speed control of a small fan motor - you ASD fucked POS !! ================================================================> > > > > I have a common 40W pedestal fan with a 13 inch dia fan blade. > > > > Tested a few minutes ago: > > > > > > > > At 240VAC rms current is 163mA. > > > > at 200VAC it became 144. > > > > at 100VAC it become 76. > > > > at 50VAC it become 33. > > > > > > > > by which time the blade was no longer turning. > > > > Not far off linear, you *must* agree.> That's specifically a FAN MOTOR,** Funny how that IS is the ** FUCKING TOPIC ** you ADD MORON ======================================================= Go save us from fucking Google monkey idiots like this 1/3rd wit. .... Phil
Reply by ●October 14, 20212021-10-14
Jasen Betts wrote: =================>> > > I suppose that for a shaded-pole induction motor in fan duty, a small > > variac would work, but would be a bit clumsy Maybe a tapped > > transformer. > > capacitor should work too. >** Yes it will, but is not so stable. Q. Why does nobody here ever trim ?? ...... Phil
Reply by ●October 14, 20212021-10-14
On Tuesday, 12 October 2021 at 22:30:39 UTC+1, Joerg wrote:> On 10/12/21 2:16 PM, Phil Allison wrote: > > Joerg 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. > >> > > > > ** Have you tried a Variac? > > > > Work just fine with most kinds of induction motor fans. > > > Yes, sorry, that was in an answer to John and not in the original post. > There is a UPS up front and that doesn't even like the smallest variac I > have. The inverter in the UPS starts to buzz and then issues an overload > shut-off even without any fans connected to its tap-off. The UPS is a > small one with a modified sine inverter, no space for anything bigger there. > > This was a puzzler to me because that same variac runs fine on a smaller > 200W modified sine camping inverter, with and without fans connected.tried an RC to reduce variac idle current? ... plus some series variable/switched R to get it all upto voltage without tripping
Reply by ●October 14, 20212021-10-14
The John Doe troll stated the following in message-id <sdhn7c$pkp$4@dont-email.me>:> The troll doesn't even know how to format a USENET post...And the John Doe troll stated the following in message-id <sg3kr7$qt5$1@dont-email.me>:> The reason Bozo cannot figure out how to get Google to keep from > breaking its lines in inappropriate places is because Bozo is > CLUELESS...And yet, the clueless John Doe troll has itself posted yet another incorrectly formatted USENET posting on Thu, 14 Oct 2021 20:47:17 -0000 (UTC) in message-id <ska50k$ta4$3@dont-email.me>. Zl04FJBbjVa9
Reply by ●October 14, 20212021-10-14
Tabby meeowed: ==============> > > This was a puzzler to me because that same variac runs fine on a smaller > > 200W modified sine camping inverter, with and without fans connected. > > tried an RC to reduce variac idle current?** Huh ??> ... plus some series variable/switched R to get it all upto voltage without tripping** The OP may need to use a NTC thermistor in series with the Variac's primary to reduce inrush current and asymmetry offset effects at switch on. Bout 200 ohms might be right. ...... Phil
Reply by ●October 14, 20212021-10-14
On Friday, October 15, 2021 at 8:12:16 AM UTC+11, palli...@gmail.com wrote:> whit3rd who needs shooting in the head wrote: > > ================================== > > > > > > > > > > > > Perhaps, but to burn the motor takes a lot of power and surely running > > > > > > > > > > the motor from a variac at reduced voltage reduces the liklihood of heat > > > > > > > > > > damage? > > > > > > > > > > > > > > > > > ** Motor current drops in line with applied AC voltage. > > > > > > > > > > > > > > > No, of course it doesn't; > > > > > ** Fraid it actually *does* with fan motors. ... > > > > Empirical knowledge of 'fan motors' doesn't relate to the class of AC induction motors. > > > =============================================================== > ** The ** TOPIC* is speed control of a small fan motor - you ASD fucked POS !! > ================================================================ > > > > > > > I have a common 40W pedestal fan with a 13 inch dia fan blade. > > > > > Tested a few minutes ago: > > > > > > > > > > At 240VAC rms current is 163mA. > > > > > at 200VAC it became 144. > > > > > at 100VAC it become 76. > > > > > at 50VAC it become 33. > > > > > > > > > > by which time the blade was no longer turning. > > > > > Not far off linear, you *must* agree. > > > That's specifically a FAN MOTOR, > > ** Funny how that IS is the ** FUCKING TOPIC ** you ADD MORONBut a 40W pedestal fan with a 13" diameter is along way from the muffin-type fans that Jeorg was trying to deal with. For one thing. it is a lot bigger. For another it is a mass-market consumer item, engineered for minim cost, when the muffin fans are manufactured in much lower volumes, for a more demanding market.> Go save us from fucking Google monkey idiots like this 1/3rd wit.Phil does seem to exemplify the breed. -- Bill Sloman, Sydney
