On Thursday, October 14, 2021 at 2:12:16 PM UTC-7, palli...@gmail.com wrote:> whit3rd <vituperation extirpated> wrote:> > > > > > > > > ** 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 !!Not the topic I was addressing, which was AC induction motors, like the one that blows air through my furnace. It's the internals of an AC motor that determine what it does with oddball power supply, not the 'fan motor' application. 'Small' wasn't mentioned, but is likewise... uninformative. What is 'small' for an aviation turbofan?
Small single-phase VFD for 120V?
Started by ●October 12, 2021
Reply by ●October 15, 20212021-10-15
Reply by ●October 15, 20212021-10-15
1/3 wit trolling maniac ==========================>> > > > > > > > > > > ** 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 !! >> > Not the topic I was addressing, >>** THEN FUCKING STOP POSTING YOUR GOOGLED UP SHITE UNDER MY WORDS !! ===================================================================== =================================================================== = You illiterate idiot.
Reply by ●October 15, 20212021-10-15
Some Ranting PiIe of Demented Shit posted ==================================> > > > > That's specifically a FAN MOTOR, > > > > ** Funny how that IS is the ** FUCKING TOPIC ** you ADD MORON > > But a 40W pedestal fan with a 13" diameter is along way from the muffin-type fans that Jeorg was trying to deal with. >** They behave ** exactly** the same way under Variac speed control. You stinking, know nothing, demented old cunt. ..... Phil
Reply by ●October 15, 20212021-10-15
piglet wrote: ==========> > palli...@gmail.com wrote: > >> 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. > > > True, there may be no back EMF.** There is none from the rotating parts.> > I think Phil has done us a big service by making actual measurements! >** The fan motor is resistive at all voltages, PF of unity. Winding resistance dominates the 50Hz impedance. The current waveform matches with the AC supply voltage. The impedance curve has a broad peak around 50/60 Hz. The 3 way speed control fitted to the fan uses tappings on the motor's windings. Interestingly, a Variac reduces the blade speed over a much wider range while using a far less current. ...... Phil
Reply by ●October 15, 20212021-10-15
On Friday, October 15, 2021 at 2:50:01 PM UTC+11, palli...@gmail.com wrote:> Some Ranting PiIe of Demented Shit posted > > ================================== > > > > > > > That's specifically a FAN MOTOR, > > > > > > ** Funny how that IS is the ** FUCKING TOPIC ** you ADD MORON > > > > But 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.I did put back the sentence that Phil had snipped. He doesn't like complicated ideas. They get in the way of his half-witted responses.> ** They behave ** exactly** the same way under Variac speed control.Your idea of "exact" looks extremely sloppy, in much the same way as your idea of "linear" did. And how you'd know that for certain is a question that invites an answer (not that you will bother giving us one).> You stinking <snip>You really should aim for a better class of abuse. "Stinking" doesn't work on a text-only group. Richard Steven Walz did better. Nobody since has come close. Your performance is down there with Flyguy and John Doe. -- Bill Sloman, Sydney
Reply by ●October 15, 20212021-10-15
Some Ranting PiIe of Demented Shit posted ==================================> > > > > > > That's specifically a FAN MOTOR, > > > > > > ** Funny how that IS is the ** FUCKING TOPIC ** you ADD MORON > > > > But a 40W pedestal fan with a 13" diameter is along way from the muffin-type fans that Jeorg was trying to deal with. > >>** They behave ** exactly** the same way under Variac speed control. You stinking, know nothing, demented old cunt. =====================================
Reply by ●October 15, 20212021-10-15
On Thursday, October 14, 2021 at 4:16:01 AM UTC-7, piglet wrote:> > Far enough off to make it perfectly clear that you haven't got a clue about what was actually going on. When the fan is no longer turning, there isn't any back EMF, so the motor windings are just inductors - and not very good inductors...Not so in an AC induction motor: those inductors transformer-couple and there's a resistive short circuit; the 'just inductors' assertion ignores the 0 ohm load resistor on the secondary.> True, there may be no back EMF. But as Phil Allison showed at 50VAC the > fan was consuming less than 2W - that is not going to make any serious > heating problem. > > I think Phil has done us a big service by making actual measurements!But those are measurements on an unknown motor; it could, for all we know, be a rectifier/DC motor, or universal type, or reluctance motor (AC but with high resistivity in the rotor). Testing tells us it's not an AC induction motor, or stepper, or synchronous type. If you want to buy a fan, and power it for speed control, the differences matter. The next 'fan motor' isn't represented by that one example.
Reply by ●October 15, 20212021-10-15
On 13-Oct-21 3:55 am, 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. 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. >I don't know for sure how a fan-rated speed-control would work, but given that motors don't like harmonics[*], the continuous speed-control would pretty have have to produce a sine wave at reduced voltage. That's what the controllers with a few positions achieve by putting capacitors in series. Running something designed for 60Hz at a different frequency does not seem like a good idea. Sylvia. [*] I once tried running a fan off a modified-sine-wave inverter. The burning smell quickly alerted me to the issue.
Reply by ●October 15, 20212021-10-15
Some 1/3 wit psychiatric patient with electrodes on his head. ================================================> > > I think Phil has done us a big service by making actual measurements! >> > But those are measurements on an unknown motor;** Same as hundred of millions of low cost pedestal and floor fans ever made. The fucking clueless one is YOU - ASSHOLE !! ------------------------------------------------------------------------> it could, for all we know,** For all YOU know - you vile, know nothing *Google Monkey* lying POS cunt. Q: Why have you not died of Covid yet ? Made pact with the fucking devil ? .... Phil
Reply by ●October 15, 20212021-10-15
On Friday, October 15, 2021 at 2:50:01 PM UTC+11, palli...@gmail.com wrote:> Some Ranting PiIe of Demented Shit posted > > ================================== > > > > > > > That's specifically a FAN MOTOR, > > > > > > ** Funny how that IS is the ** FUCKING TOPIC ** you ADD MORON > > > > But 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. > > ** They behave ** exactly** the same way under Variac speed control.That's Phil's assertion. Since he doesn't seem to have an example of Jeorg's muffin fan - a Pabst all-metal muffin fan with a shaded pole motor (which is still pretty unspecific) he does seem to be lying. "Over-confident" is a nicer way of saying the same thing, but who'd bother being nice to Phil? <snip> -- Bill Sloman, Sydney
