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18th Oct 2016, 01:49 PM #16
Sure, if you are not careful or are unaware.
I bought the welder for around $100 (completed with remote feeder) and spent maybe $20 on converting it. I have welded everything from 0.9mm sheet through to 25mm plate. It's on a 15A circuit and I keep an eye on cable/plug temps when it's running anywhere near full noise.
Best $120 I ever spent on a welder.Cheers.
Vernon.
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Bite off more than you can chew and then chew like crazy.
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18th Oct 2016, 05:28 PM #17Most Valued Member
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Looks like these capacitors will be the hardest parts to find of the build, Does anyone know of US friendly shops that ship to AUS? i found oil capacitors in the US for $5 but over here they are $50-$100 each which is crazy
looking for 24uf 480VAC oil filled
can't seem to find them anywhere in OZ i wonder why? 3 phase is pretty common here on the commercial scale and electric motors are everywhere so strange i cannot find them
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18th Oct 2016, 06:25 PM #18
Short answer is no, because there is no where that it can be included in a driven induction motor to have regulating effect.
Induction motors (single or three phase) like the one you bought only have one set of true 'run' windings per phase, and the single phase have an additional 'start' winding to get them turning then it is switched out of circuit. The armature (rotating part on shaft) consists of a metal core on the shaft with a handfull of copper or ali rods parallel to the shaft set into the core, and all joined at each end.
An alternator armature has a winding wound concentric to the shaft, and housed in a different core structure. The armature is driven at an appropriate speed to control the output frequency, and the DC current flowing through the concentric winding is controlled by the regulator to set the output voltage.
If you ever get a chance, look at some of the older generating plants in museums, preservation societies etc. They generally have the engine, alternator and exciter arranged in that order. The exciter is a DC generator that creates a current that is fed through the armature winding of the alternator to 'excite' the alternator, or create a magnetic field at the armature. When this field is forced to rotate by the engine, the magnetic field at the armature rotates and the constant change in magnetic field induces voltage in the main or stator windings, which is then distributed to operate other loads.
EDIT: Just found the bit enquiring about capacitors etc. Not commonly found here because there is not a huge DIY 3phase experimenter population here. Capacitors are not required when using the motor as a motor, so there are not a batch of capacitors installed with the motor normally.
Beware of buying 480VAC caps for that application with a 415V target as the voltage rating is rather close. If when these things (capacitors) get overvoltage applied, the results can be somewhat loud and smelly. I would be looking at 600VAC min, and they will be rarer/dearer still.I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.
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18th Oct 2016, 07:47 PM #19Most Valued Member
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Malb i hear you mate, i just read a little information about capacitors and voltages, it said along the lines the capacitors voltage is the max voltage it can take, this may have been why the person in the link said to use 480v capacitors maybe in a way of limiting the generators output of voltage so it only destroys the capacitors rather than what the generator is powering? (welder)
also read about uF which from my understanding is like a wave length if u go over or under it can put to much load on either the motor or capacitors
so now im looking for 500v and 24uF or 25uF i will up my search to include up to 600v capacitors
their are online calculators for motor RPM's and pulley sizes and all other sorts of information i should be able to get close to the required generator RPM if i use a sufficient drive motor, i am trying to find s 2800-2900RPM drive motor so i can run two 100mm pulleys as the pulley on my generator is 100mm and requires 2900RPM
forgot to mention before when i removed the cover on the generator motor it showed both wiring config's so it should be simple to convert
i found a petrol Honda copy motor on the internet very cheap i thought about using it to power this beast of a motor but than thought it may be a bugger to move as the electric 3 phase motor weighs along 71kg so if i go electric drive motor i can just install it in the shed corner and leave it there, no fumes and no carbon monoxide to worry about while working
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18th Oct 2016, 07:56 PM #20Pink 10EE owner
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Whilst I do not think this is going to be a successful project and you would be better off building a rotary phase converter.
The capacitors you require are called CBB65A type. Most commonly in 450V, however there are some 500V ones available eg: AC 500V 20uF Air Conditioner Motor Run Capacitor CBB65A | eBay
Phase Change Converters based outside Melbourne use 600V versions in their phase converters. Whether they will sell you any is another question. They have sold them to me, but I have one of their phase converters and it was for them. They are around $30 each.
You will probably have other issues like switchgear to sort out as well. You are not going to build a 7.5kw device without some serious input amperage. I have an 8kw phase converter and it runs off a 50 amp breaker however when I start the lathes 7.5hp motor, it dims the lights in the house and the line voltage drops. You do not actually say what you want to run in any detail so offering advice is not very easy. A lot of us have been where you are now and how we went about things might have been different if we knew back then what we know now.Gold, the colour of choice for the discerning person.
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18th Oct 2016, 09:05 PM #21Most Valued Member
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Thanks RC, i found this link about RPC's seems simple to make and i am halfway there diy - How to Build a Rotary Phase Converter to Convert Single Phase to Three Phase
To make a simple rotary phase converter out of a 3 phase motor
Connect 230 volt single phase power to the T1 and T2 supply terminals (or wires) of the motor that you are using as a converter.
Get it Spinning (with a rope wrapped around the motor shaft for example) to get it going - it won't start on its own.
Take 3 phase power off of the T1, T2, and T3 terminals to power your three phase shop equipment.
but look here i don't understand this
Add run capacitors - A phase converter will work just fine without run capacitors, but they will improve performance and efficiency to some degree. Run capacitors must be rated for continuous duty at high voltages (330-370 Volts) and are permanently connected between the T1-T3 and T2-T3 connections. Ideal voltage balance is difficult to achieve without some kind of dynamic adjustment, because different load states will require different configurations of run capacitors. But it really doesn't matter that much in most cases for motor loads. Just use about 12-16 microfarads per rated horsepower of the idler as a general rule.
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18th Oct 2016, 09:16 PM #22Pink 10EE owner
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18th Oct 2016, 09:58 PM #23Most Valued Member
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RC That is a great idea the zip start i have never seen anything like it on a piece of machinery haha
i have a question, i only plan on running 415v 3 phase so i don't need 480v and 240v 3 phase but from my understanding of reading those threads the idea is to keep the welder as a welder and multipal power output source am i correct or does the welder play a part in converting or maintaining the 415v 3 phase power?
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19th Oct 2016, 01:08 AM #24
That s a good little introductory article on rotary phase converters. BUT you have to read all of it! I think you missed the bit about star and delta wiring "....The motor that you are using as a generator (rotary phase converter) is called an idler, and needs to have a 20-30% higher horsepower rating than the largest equipment motor that you will be using, and needs to be rated for 220-240 volts."
The motor you have is NOT suitable, because it is a DELTA 415V motor. The rewiring information you seem to have found is to make it a STAR 586V motor. There is actually no such voltage in use. The reason your motor could be switched from Star start to Delta run is to reduce the current it draws on start-up. A direct on line start current of a 10Hp motor will be HUGE and the star-delta switching is done to keep that in check.
Friendly comment:
if there is anything in the articles you read - or our responses to your questions - that means you may well have missed a CRUCIAL concept. You MUST research and understand EVERYTHING in build instructions or you will risk you life! From your questions, it is clear that you don't know or understand a lot of electrical concepts and physics.
Please be careful! We would hate to loose you.
As a result, I'm also loathe to give you any advice - information yes! - but no more "how to's". I would not sleep at night if you got harmed or worse because you misunderstood something I write.
For example: lots of insulation is NOT rated for 500V or more, and some of the spikes you may well generate could be higher than that.
Please be careful.Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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19th Oct 2016, 01:25 PM #25Most Valued Member
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I think i mentioned it came with instructions for DELTA or WYE mate its under the cover on a diagram
i know i am playing with big voltage here so i want to take precautions, i know the output can be up to 500-600v which is deadly and i know about the capacitors holding charge...
there wont be any tinkering with live wires while the motor is turning over or connected to 240v the only thing i need to do while the motor is running is to check the voltages with a multimeter for later adjustments of the capacitors sizes to get close to 415v across the three terminals
as for live power past the generator between the welding machine and converted motor i will use a RCD for 415v
, i also i read the whole link mate i just never mentioned the wiring config of the motor because i had seen it under the cover, i also read this link too
phaseconverter
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19th Oct 2016, 01:27 PM #26Most Valued Member
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Here is the wire diagram
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19th Oct 2016, 04:25 PM #27Most Valued Member
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I sent out around 5 emails to AC electricians in my area found on Gumtree, one reply so far and the electrician is willing to look over my wiring once i finish building my generator, i think if i hire a electrician this is the better way to go about it and it should only cost $100-$150 (1 hour labour)
I'm going to try make the 2 motor conversion as in one of the links i have posted it said it was a more pure power source running the small start and run motor with the idler motor
I'm unsure if i want a stationary power source or adapt my generator to a furniture trolley so i am able to wheel it around my back yard along with the welder but in doing this that motor is very heavy so unsure yet
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19th Oct 2016, 10:32 PM #28
I know, that's why I gave you the note that you motor is NOT suitable. As I said in detail, when you change it from delta to wye, it will become a 586V motor. That setting is for starting only.....
I don't believe you understand the implications of Star/wye and Delta configurations or the significance has escaped you....Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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19th Oct 2016, 11:58 PM #29Most Valued Member
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OK I'm with u now, my motor is wye or delta but it is currently wired in delta for high voltage, i had a read back thru my links i have posted and it seems i should be focusing on a induction generator rather than a rotary phase converter which the induction generator was plan A
now in the link on page one the guy i assume its a guy is saying the generating motor must not go over its rated RPM due to the higher revving of the motor producing in excess of 415v as others have already mentioned in this thread
i think it may be trial and error with pulley choices and possibly some sort of drive motor speed controlling to to control the over all voltage of the generating motors RPM to sit around 415v it may be hard to control and keep close to 415v under load the person in that link did mention the voltage under load dropped
am i on the right level now?
the video below is what i am trying to do however i know this bloke must have had a few beers to ve over revving the generator taking the capacitors up to 90htz but this falls under controlling the drive motors speed to achieve the power voltage i require
https://www.youtube.com/watch?v=y-bPJ2SZp7o
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20th Oct 2016, 09:57 PM #30Most Valued Member
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I picked up a small drive motor yesterday to give me a idea on what size i would need, it came with the power cord cut completely off so i done some re-wiring had to pull half of the motor apart than put it all back together i than fired it up only to hear it hum so i think the reason the cord was cut because someone knew the capacitor was shot
i had connected up the induction motor with a drive belt to this small drive motor and with a bit of a push start this little drive motor spun up the large 10hp induction motor
the little drive motor is only rated to 1450RPM with using a pulley calculator taking in the sizes of pulleys i was turning over the 10hp induction motor at 1305RPM no where near its 2900RPM run speed
i than checked for AC voltage but only got 1 watt so i think the induction motor needs to be energized by 12volts
i will check it out further tomorrow, i have read it only takes 1 second to energize so we will see
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