single to 3 phase conversion for delicate equipment ? - Page 1
Forum section: electronics / projects

author: Alphatronique
author_rank: Regular Contributor
timestamp: April 10, 2015, 05:35:34 pm
content: Hii finally broke the bank and buy a top of the line "almost" new pick & place machine O0so now i have on shop only 120 and 240 v single phase supply 120 was phase neutral and 240 was phase / phasethen i need 208 3-phase 2.2kva / phase (1.8KVA average )so for now i have rejectrotary phase converter , lack of balance and not like wide variable load specially at machine idel whit light loadphaseperfect digital converter , to mutch expensive and 2 phase pass troug it and generate the third one whit PWM so 180 deg + 180 deg + ? not 120 deg phase ,still need 10kva transfomerbring 3 phase to the house , local utility power compagnie not like idea to bring commercial 3 phase into a residential house and only supply it 600volt and not what 600 volt on my houseScott-T transformers , not understand well how it work and some said it work some saidit not work in north america singes phasehack power supply of machine , MyData will refuse to service it one modified ,and that kind of baby need some support someday (line scan camera , linear motor and so on .... )so any idea or suggestion ?

author: Kleinstein
author_rank: Super Contributor
timestamp: April 10, 2015, 06:03:38 pm
content: A rotary converter should be the cleanest solution. It depends how well they can handle varying loads, but some can do that quite well. It may have to be a little larger, like 7,5 kVA oder 9 kVA. The main downside is that it produces some acoustic noise and the voltage may not be very stable. Installation is something for a qualified electrician anyway.The 600 V are not such a big problem - this just needs a separate local transformer. Typical the unit can be well enclosed, so safety is not a problem. Using weak existing lines up to there maximum current rating is the larger danger. Usually more people die from fire caused by overheating electric systems due to high current than from electrocution - so the American 110 V is more dangerous than the European / Australian 230/240 volts.

author: Alphatronique
author_rank: Regular Contributor
timestamp: April 12, 2015, 01:48:49 am
content: Hiwhit 600V it more think about re-sale of the house later ,and redo power entry was not so cheapand usually my local electric company not install 3-phase on residential aeraprobably that will end-up whit hack the machine even if not really like that option

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 12, 2015, 04:28:00 am
content: A surplus VFD plus some LC filters to smooth out the output?

author: Ian.M
author_rank: Super Contributor
timestamp: April 12, 2015, 04:41:37 am
content: I was thinking motor-generator set. Take the three phase alternator head off a genset with a wrecked engine and couple it to a beefy induction motor. Add a VFD on the input if you need accurate frequency control, otherwise a single phase motor or static phase converter would do if you don't mind the output frequency being low by the slip percentage.

author: calexanian
author_rank: Super Contributor
timestamp: April 12, 2015, 06:37:45 am
content: Typically one would use a flywheel system with a rotary phase converter. Otherwise ask the manufacturer of the machine for a recommendation.

author: Psi
author_rank: Super Contributor
timestamp: April 12, 2015, 06:41:55 am
content: Could find a 2ndhand 3phase industrial UPS from like a datacenter.Then hack it to always run on battery and find a powerful single phase PSU to float charge the batteries.Or, you could always modify your machine to run on single phase power but do so in such a way that it's easy to return to factory spec without any evidence you modified it.Obviously you would have to avoid any onsite support visits since its not usable once returned to 3phase mode.

author: jeff.remus
author_rank: Contributor
timestamp: April 12, 2015, 03:15:49 pm
content: Yet another was is with an LVG or line voltage generator. The work similar to audio amplifiers one channel per phase. Aetechron.com

author: Alphatronique
author_rank: Regular Contributor
timestamp: April 12, 2015, 03:24:18 pm
content: Hi"Otherwise ask the manufacturer of the machine for a recommendation" --> company was not cooperative at all on it used machine until you paid ,training ,registration and installation so 10,000$ ,then maby it help or notas for UPS until now all that i see was terrible expensive ans 3 phase in 3 phase out , and phase perfect digital phase converter + tranfo may cost less effective @ ~5000$ ,bit still quite expensive"A surplus VFD plus some LC filters to smooth out the output" --> make sense but most VFD have motor start-up sheme build in that bit afraid me of how it may react to machine operationthat not ack like a induction motor at all , i not yet fin a plain drive whit not ton of fancy option that may screw-up the thinghttp://aetechron.com/that great no knot that company ,but honestly a 10kva system was for sure not cheap at all ;-)

author: jeff.remus
author_rank: Contributor
timestamp: April 12, 2015, 03:25:11 pm
content: Just to help balance the load there are balance transformers and capacitors that are used on grid tie photo voltaic power inverters. I have them in my zantrax PV45 but I have not measured there performance. I have seen the balance transformers on YouTube. If you have an osciloscope take a look at the three voltages and then the three current clamps to see what is really going on first before you spend any money.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: April 12, 2015, 03:27:15 pm
content: Quote from: Alphatronique on April 10, 2015, 05:35:34 pmA bit OT, but how did the formatting of the post end up this crazy way?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 12, 2015, 03:53:43 pm
content: It might be worth looking at exactly what the 3-phase supply is going into - it may be the case that it's going into switchmode PSUs, in which case you may be able to run it from a higher voltage single phase supply (or maybe DC) , or replace the PSUs with single phase ones.It could simply be that the only reason it's 3-phase is that's what most of their customers have in their factory, rather than actually needing it to be 3-phase for a technical reason..

author: DanielS
author_rank: Frequent Contributor
timestamp: April 12, 2015, 04:15:22 pm
content: If the machine's power supply is simply a 3-phase to DC converter with diodes dumping line voltage across a single input cap bank, you should not need to lose sleep about having perfect conversion. You could have a 300VDCsupply connected to a single pair and the supply's rectifier would most likely be fine with 8ADC. Of course, you would need to open the supply to verify how it is designed and the input components' ratings before doing this.Unless the power supply also has power factor correction, you should not need more than a simple modified square wave driver to run its three phase input if you insist on spreading the load across all input diodes.BTW, one of the big benefits of 3-phase power is achieving better than 10% ripple before adding any filtering caps. You may need quite a few caps to get single-phase ripple that low.

author: amyk
author_rank: Super Contributor
timestamp: April 12, 2015, 04:19:02 pm
content: Quote from: mikeselectricstuff on April 12, 2015, 03:53:43 pmThat's what I was thinking too - 3-phase is usually necessary because it's being used to power large continuously rotating induction motors, of the sort used in CNCs and lathes. A P&P doesn't seem to me like it'd have such a motor, although the 3-phase supply might be more due to high power consumption.

author: cosmicray
author_rank: Frequent Contributor
timestamp: April 12, 2015, 04:21:25 pm
content: Quote from: Alphatronique on April 10, 2015, 05:35:34 pmDo the utility lines on your street even have 3 phase available ? When I live, there is a single 10kV line to a transformer on a pole.

author: Towger
author_rank: Super Contributor
timestamp: April 12, 2015, 04:39:24 pm
content: Ask per Mike and Co. What in the machine actually needs a 3 phase supply? Do you have documentation or the actual machine yet. It may not require much to convert to single phase.