AMMO Posted October 3, 2007 Share Posted October 3, 2007 One for the clever electrical bods. The Superflow 600 flowbench at work has eight 1.000 Watt single phase motors. When you switch the flowbench on, the motors all run flat out. Very noisy! The airflow is controlled by mechanically restricting the flow. Subsequently the motors get very hot as they rely on air flowing through them for cooling. During continuous testing the motors can burn out. This happened recently and is quite common but the first time it has happened to this flowbench. My old 110 Superflow probably burnt out six motors in ten years. Lotus Engineering had two 600 flowbenches so if one failed in the middle of testing they could use the other one while the broken one could be fixed! The motors don't need to run flat out. If their speed could be acurately controlled to give the desired airflow they wouldn't get so hot and they would be quieter as well. I used to own a Superflow 300 that had a motor controller and Flowcom computer. This didn't have any problems with motors burning out. The only problem is that the Flowcom and motor controller is going to cost a couple of grand and we only fire up the flowbench once or twice a month and we can't justify the cost. Anybody got any bright ideas? I would like something that can control the motors with a potentiometer mounted to the console. Is something like this possible? Thanks AMMO Edited by - Ammo on 3 Oct 2007 19:04:23 Link to comment Share on other sites More sharing options...
Peter T Posted October 3, 2007 Share Posted October 3, 2007 here Link to comment Share on other sites More sharing options...
Johnty Lyons Posted October 3, 2007 Share Posted October 3, 2007 here Sorry Ammo its not that cheap but VSDs are expensive You could still do it for under a grand though I use Wacking big VSDs on HVAC equip for noise reasons during Retail opening Controlled remotly by Trend com equipment from this laptop at home Edited by - Johnty Lyons on 3 Oct 2007 19:39:15 Link to comment Share on other sites More sharing options...
Peter T Posted October 3, 2007 Share Posted October 3, 2007 here Link to comment Share on other sites More sharing options...
Peter T Posted October 3, 2007 Share Posted October 3, 2007 Snap Link to comment Share on other sites More sharing options...
rj Posted October 3, 2007 Share Posted October 3, 2007 Erhm.... Couldn't you just turn on one motor at a time and then just make the first one controlable? /regin (looking at airboxes as I type...) Link to comment Share on other sites More sharing options...
Delberts Wallet Posted October 3, 2007 Share Posted October 3, 2007 VSD's are the way to go really. Correct control and soft start will cut down on noise andd starting current plus less wear and tear. An 8kW VSD shouldn't cost the earth, I'll check our price list when the Mrs gets back with my laptop. Johnty, do you mean Trend controls? Gareth Blue and Carbon 6 Speed Supersport here Link to comment Share on other sites More sharing options...
Johnty Lyons Posted October 3, 2007 Share Posted October 3, 2007 Yep great bits of Kit I have all the plant on them Control via VPN and web browser jj N.I. L7C AR 🙆🏻 Membership No.3927. Link to comment Share on other sites More sharing options...
Johnty Lyons Posted October 3, 2007 Share Posted October 3, 2007 obviously an 8Kw VSD will be cheaper than 8 by 1Kw units But I have a sneaking feeling he needs to control 8 Individual motors ☹️ jj N.I. L7C AR 🙆🏻 Membership No.3927. Link to comment Share on other sites More sharing options...
Delberts Wallet Posted October 3, 2007 Share Posted October 3, 2007 I know its great kit, I work for them 😬 Gareth Blue and Carbon 6 Speed Supersport here Link to comment Share on other sites More sharing options...
Delberts Wallet Posted October 3, 2007 Share Posted October 3, 2007 I take your point Johnty. AMMO, is it possible to swap out the 8 1KW motors with a single 8KW (or there abouts) motor? Gareth Blue and Carbon 6 Speed Supersport here Link to comment Share on other sites More sharing options...
Bricol Posted October 3, 2007 Share Posted October 3, 2007 No idea of the internal workings of this thing, but instead of shuttering the air flow, why not simply re-direct it - turn some of the flow off to an exhaust somewhere, directing the flow you want through the unit, thus keeping the air flow thro the motors at a level to cool them. A quick perusal of someone like CCL Lindab's website might indicate if suitable trunking is available to do this. Bri Link to comment Share on other sites More sharing options...
Johnty Lyons Posted October 3, 2007 Share Posted October 3, 2007 Gareth *thumbup* jj N.I. L7C AR 🙆🏻 Membership No.3927. Link to comment Share on other sites More sharing options...
DaveMorris Posted October 3, 2007 Share Posted October 3, 2007 Ammo, 1/. any chance of picccies of this device for those of us whop don't know what it looks lile. 2/. I agree with the VSD option, this makes sense BUT 3/. Burning out of motors due to overheating indicates a poorly designed system IMHO. (At the risk of talking utter tosh) - If the fans are not sucking thru the flowbench then they should be enabled to suck from elsewhere to ensure adequate cooling is maintained. Confirm whether you'd need one off 8kW VSD or 8 x 1kW VSD's (We might have one lying around at work - though as it will be 3ph I don't know whether it wll be suitable for single phase). X-flow(er) power now resting. Trying Vx for a change. Link to comment Share on other sites More sharing options...
Area Representative Richard Price Posted October 3, 2007 Area Representative Share Posted October 3, 2007 I'd guess these are capacitor start/run motors, and most VSD's are 3phase output even if they are single phase input, so may not be compatible with these single phase motors. Couldn't you just turn on one motor at a time and then just make the first one controlable? I'm with Regin on this If it's feasable to run less motors to get less flow, then why not just wire in individual switches for each motor and switch in motors to get the volume of flow that you're looking for. Certainly much cheaper than either a single 8kW or 8, 1kW VSD's. However, it may not be that simple. The motors that are running, may suck or blow air through the one/ones that are not running and just circulate the air, so maybe some form of non return valve would also need to be incorperated. Link to comment Share on other sites More sharing options...
AMMO Posted October 4, 2007 Author Share Posted October 4, 2007 Many thanks to all of you for your replies. I too like Regins way of thinking. Most of the times the simplest solutions are the best. Switching the motors you don't need off sounds like a good idea. I also agree with Dave Morris that the system is poorly designed and could be improved upon. There is a by-pass for the air when the valve openings on the test cylinder head are small. This is quite crude. Last night I remembered last night that our friend Blackbirdman used to work in stage lighting so I gave him a call. He's going to look into some 2,000 Watt dimmer switches for me today. To able to control the eight motors in banks of two sounds quite good. Might need to have them all running slowly rather then shutting them down completely as you may get the suck / blow problem Richard envisages. Going to try to get some time on the flowbench today to identify the faulty motors and disconnect them. They still seem to run but are down on power and smell really bad! I'll see how the flowbench works with some motors disconnected. Keep any other ideas coming. Thanks again. AMMO Link to comment Share on other sites More sharing options...
Beelzebub Posted October 4, 2007 Share Posted October 4, 2007 Hang on a minute, I'm no expert but I'd exercise caution. ISTR that dimmers for incandecsent lamps won't work/will damage an AC electric motor. I stand to be corrected on this.......Just something to think about. D. Link to comment Share on other sites More sharing options...
Sheds Moderator Posted October 4, 2007 Share Posted October 4, 2007 Sounds like you need a triac dimmer on #1, then switch the others on as required. AFAIK a triac dimmer will not damage a motor - I imagine they are asynchronous motors so the speed is regulated by the mains freq? Can you get 1kW triacs these days? Link to comment Share on other sites More sharing options...
Sheds Moderator Posted October 4, 2007 Share Posted October 4, 2007 Doh! If it *is* an asycnronous motor, as would make sense, then a triac based dimmer will reduce the power but not the motor speed. You need a freq controller. [Note to self - revise basic electrical knowledge before posting...] Link to comment Share on other sites More sharing options...
Ian B Posted October 4, 2007 Share Posted October 4, 2007 our friend Blackbirdman used to work in stage lighting so I gave him a call. He's going to look into some 2,000 Watt dimmer switches for me todaySuggest you remind Matt that the Projects Department was in a different company to the Dimmer Sales one he used to work for, albeit in the same building ( Matt ). Dimmers to control motors, they will simply chop the waveform and cause the motor windings to overheat. You need a proper motor controller (eg the VSD's referred to earlier) to control the speed. Ian - MI 5EVN - Slightly Vider SVelte model 😬 now repainted to match the Autocom headsets 😳 Link to comment Share on other sites More sharing options...
AMMO Posted October 4, 2007 Author Share Posted October 4, 2007 The plot thickens! The motors are 120V in series. They are not in groups of two though. I'll try to explain. Imagine all the motors have a white wire and a black wire. Grab four motors and connect all the white wires together. Grab the other four motors and do the same. Grab all eight of the black wires and join those together. Feed 240 volts into the white wires and all the motors run. One of the motors was sparking badly at the brushes so I disconnected it. Due to the air flow the motor still turned whilst disconnected when I switched on the flowbench. Difficult to see exactly what is happening due to the fact that I'm lying down on the floor squinting through an inspection cover. Didn't really come to any conclusions and haven't identified if the motor that was sparking is faulty or not. Tomorrow I will take a digital voltmeter to work and check each notor individually to see if can find any more clues. Thanks again for your help AMMO Link to comment Share on other sites More sharing options...
rj Posted October 4, 2007 Share Posted October 4, 2007 Ammo, By disconnecting one motor you'll have over-voltage across the remaining three in that "batch" You can look at it as being four seperate circuits consisting of two motors in series when everything is ok. it would work exactly the same if just one white wire was connected to one black. You need to disconnect one motor from the other bank as well. Hope this makes sense... /regin Link to comment Share on other sites More sharing options...
Area Representative Richard Price Posted October 4, 2007 Area Representative Share Posted October 4, 2007 One of the motors was sparking badly at the brushes so I disconnected it Ah, they are not single phase induction motors, but compound motors, more like a DC motor, and therefore not dependant on the supply frequency for their speed! So the light dimmer idea is likely to work. Link to comment Share on other sites More sharing options...
rj Posted October 4, 2007 Share Posted October 4, 2007 Or in fact the regulator of a handheld drill... Which you can get dirt cheap and just fit a pot instead of the push-button. Those are made to control a motor aren't they? Link to comment Share on other sites More sharing options...
DaveMorris Posted October 4, 2007 Share Posted October 4, 2007 Don't motors run hotter when running slower though (this thread is bringing up so many things that I have forgotten or only partially recall from yesteryear that it's worrtying me ) X-flow(er) power now resting. Trying Vx for a change. Link to comment Share on other sites More sharing options...
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