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$1@dont-email.me>:> The reason Bozo cannot figure out how to get Google to keep from > breaking its lines in inappropriate places is because Bozo is > CLUELESS...And yet, the clueless John Doe troll has itself posted yet another incorrectly formatted USENET posting on Fri, 15 Oct 2021 19:37:38 -0000 (UTC) in message-id <skcla2$h9d$8@dont-email.me>. EsCAg/cyW1Ql
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
Phil Allison <pallison49@gmail.com> wrote:> Cydrome Leader 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. > > ** Nonsense - that never happens. > You must have some other issue going on. > > > A VF drive ... > > ** Is an insane idea. > > >> > Good point, could be a design flaw in the UPS. I can check that. >> >> Unfortunately, any UPS that's not really true sine wave is a design flaw. >> > ** Yawnnnnnnnnn....... wot drivel,.UPSes that do not make a clen sine wave are cheap garbage, period. Cheap was the key factor in design, and the quality of the output power is junk.>> Manufacturers will even pass square waves off as "modified sine wave". > > ** Works just fine with SMPSs.Super. All loads are SMPSs. Nothing else exists.>> While a VFD should rectify this ugly input and make a new AC wave for the >> motor, > ** Nut case idea.I guess you're too old to have ever seen a VFD.> but good luck finding one speced to take input from a dubious UPS >> and work correctly. > > ** Bet any one you find will work just fine. > > ...... PhilSure. Chinese knock offs of knock offs will surely have excellent noise filtering and work to to all claimed specs all the time.
Reply by ●October 15, 20212021-10-15
Sylvia Else <sylvia@email.invalid> wrote:> 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.don't tell phil alison. garbage UPSes are perfect for all applications.
Reply by ●October 15, 20212021-10-15
Cydrome Leader writes Bullshit : =========================> > > > >> > Good point, could be a design flaw in the UPS. I can check that. > >> > >> Unfortunately, any UPS that's not really true sine wave is a design flaw. > >> > > ** Yawnnnnnnnnn....... wot drivel,. > > UPSes that do not make a clen sine wave are cheap garbage, period.** Yawnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn.......> >> Manufacturers will even pass square waves off as "modified sine wave". > > > > ** Works just fine with SMPSs.> Super. All loads are SMPSs. Nothing else exists.** Insane drivel. UPSs and DC inverters are sold for PARTICULAR types of use. Modified sine waves types are very good for many uses, from lamps to TV sets. Horses for courses.> >> While a VFD should rectify this ugly input and make a new AC wave for the > >> motor,> > ** Nut case idea.> I guess you're too old to have ever seen a VFD.** I had a DIY design for one published a national electronics magazine. Specially engineered for multipole, synchronous motors as used in hi-fi turntables. Perfect sine wave output. Tested the prototype using a 120mm square AC fan. ...... Phil
Reply by ●October 15, 20212021-10-15
On 10/14/21 4:44 PM, Tabby wrote:> 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 >It does get up to voltage but the inverter buzzes and then after 2-3 sec trips off with an overload warning. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●October 15, 20212021-10-15
On 10/15/21 2:17 AM, Sylvia Else wrote:> 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. >That is normal though, that's the core job description for VFDs.> Sylvia. > > [*] I once tried running a fan off a modified-sine-wave inverter. The > burning smell quickly alerted me to the issue. >I've done it many times during power outages, mainly to bridge the time until I got the generator schlepped around the house, cables laid, fueled up and started. However, this was a cheap camping inverter. Works. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●October 15, 20212021-10-15
On 10/15/21 10:57 AM, Rich S wrote:> [snip] >> 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/ > > Hi Joerg, whatever variable-drive- speed control method you go with, consider one that provides: > (a) initial full power, for ~5 seconds, to ensure fan gets up to speed > (b) closed-loop control, like a tachometer (optocoupler, etc.) > since for some motors (those not designed to be varied) the drive isn't predicable or linear formula... > cheers, RS >Well, the pickens are already super-slim to non-existent so I can't be choosy. Looks like I'll have to build my own. Not a problem but I don't want to have yet another project. BTW, when I tried "mock VFD" with a generator and a big audio amp it worked beautifully and the fans also ran with much less buzz. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●October 15, 20212021-10-15
Stupider than Anyone Else wrote: ===========================> > 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. >** VFDs are intended to be used with specific classes of AC motor and nothing else. Those with expertise may find other safe uses. AC voltage and frequency are reduced or increased in * proportion* to to avoid any overheating.> [*] I once tried running a fan off a modified-sine-wave inverter. The > burning smell quickly alerted me to the issue.** Some AC fan motors run quite hot - saw a large outdoor, pedestal type do that recently. The motor overheated and shut off at low speed settings due to inadequate internal air flow. However it worked perfectly with my Variac. Fixed it by opening up the slotted rear air entry and fitting a steel fan grill instead. ...... Phil
Reply by ●October 15, 20212021-10-15
Joerg wrote: ===============> It does get up to voltage but the inverter buzzes and then after 2-3 sec > trips off with an overload warning.** Might need a series RC snubber across the output of the inverter. The Variac might have emf kick backs when driven by a modified sine wave. Use your scope to have a look FFS ...... Phl
Reply by ●October 15, 20212021-10-15
lørdag den 16. oktober 2021 kl. 01.00.28 UTC+2 skrev Joerg:> On 10/15/21 10:57 AM, Rich S wrote: > > [snip] > >> 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/ > > > > Hi Joerg, whatever variable-drive- speed control method you go with, consider one that provides: > > (a) initial full power, for ~5 seconds, to ensure fan gets up to speed > > (b) closed-loop control, like a tachometer (optocoupler, etc.) > > since for some motors (those not designed to be varied) the drive isn't predicable or linear formula... > > cheers, RS > > > Well, the pickens are already super-slim to non-existent so I can't be > choosy. Looks like I'll have to build my own. Not a problem but I don't > want to have yet another project.https://www.amazon.com/Inverter-EGS002-EG8010-IR2110-Driver/dp/B01E8X64CC https://www.lz2gl.com/data/power-inverter-3kw/eg8010_datasheet_en.pdf ;)
