Carl.H
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 posted on 23/1/04 at 06:00 PM |
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3 PHASE HELP!!!!
Hi all
Any of you know how I might convert a milling machine with three 3ph motors on it to run on 1ph here are the details:-
Motor 1
hp- 2
V- 220/250-380/440
Rev/min- 1420/1710
A- 6.4/3.7
Motor 2
hp- 0.75
V- 220/250-380/440
Rev/min- 960/1160
A- 2.6/1.5
Motor 3
hp- 0.33
V- 220/250-380/440
Rev/min- 1425/1725
A- 1.05/0.56
I’m looking for an inverter at the moment but expensive (£150 +)
I’m thinking there must be a way to do it using capacitors and transforms, but as for how I haven’t a clue.
Any help, suggestions gratefully accepted.
Thanks
Carl
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splitrivet
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| posted on 23/1/04 at 06:04 PM |
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Change the motors is the best, anything else is decidedly dodgy.
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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Carl.H
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| posted on 23/1/04 at 06:12 PM |
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not easy flange mounted so hard to get hold of, but replacing the motors the easiest way
thanks
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colibriman
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| posted on 23/1/04 at 07:26 PM |
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looks like they are already capable of being fed by 1ph....as per the 220/250v part of the label....
you should be able to rearrange the links in the motor terminal box to suit (as long as they are there - should be 3 brass removable links under the
terminal nuts...)..........
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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David Jenkins
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| posted on 23/1/04 at 07:47 PM |
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I had similar problems with my lathe - 1.5HP main motor and 1/8HP for the cutting fluid pump.
If you use a phase converter then you have to buy one to match your motor - and if you have 3 then the load varies so it's near impossible to
match. The solution is to have an old 3-phase motor running permanently (it can be tucked away somewhere) - this keeps the 3-phase supply in sync,
and allows you to turn motors off and on as you please. This is called a pilot motor, and can be an old salvaged one.
Now for the bad news - you'll need a big converter, and they're expensive. If you change the motors to single phase you'll find
that the replacements are considerably bigger than the originals (3-phase don't need starter windings).
Colibriman - you're wrong, I'm afraid - 3-phase motors can be described as 220v or 415v, depending how they're wired (star or
delta). The motor has 3 windings that come out to 6 terminals, offering you the choice of how to wire them.
I suggest that you ring a phase converter supplier and ask for advice... I have my instructions somewhere, if you need a phone number.
cheers,
David
[Edited on 23/1/04 by David Jenkins]
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Andy W
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| posted on 23/1/04 at 07:49 PM |
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You can't just connect the motor to single phase. The 220/250v is for when the motor is run through a single phase invertor, basically giving
you 240v 3 phase. Note the extra amps the motor takes 6.4 compared to 3.7amps at 415v.
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dblissett
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| posted on 23/1/04 at 08:43 PM |
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3 phase
have a look at the terminals on the motor conections if you have 6 leads or studs you are in luck
if you have six you can conect the motor in delta and buy a single phase inverter
this will convert single phase 240v to 3 phase 220v
ie single phase in, 3 phase 220 volts out
we use them at work and they are very good up to about 3hp from single phase
if you have the six conetions get back intouch and i will help you out
if you must change the motors you will need to find out what frame size they are i guess they will be d71 or d80 this gives the supplier the
dimentions of the motor
if posable stay away from single phase motors that replace your three phase ones as there starting torque is nowhere near the three phase
equiverlant
cheers dave
[Edited on 23/1/04 by dblissett]
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stephen_gusterson
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| posted on 23/1/04 at 10:11 PM |
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your best bet is a motor speed controller - an inverter as you call it.
these can take in single phase and convert it to three phase at variable frequency - allows you to control the speed.
you would need three......
most industrial motors are three phase...
atb
steve
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David Jenkins
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| posted on 23/1/04 at 10:20 PM |
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Try this company - they're favourite with model engineers who buy industrial 3-phase machines:
Power Capacitors Ltd
30 Redfern Road
Tyseley
Birmingham
B11 2BH
021 708 4522
They're a really helpful company, and can advise of the best way to set yourself up.
cheers,
David
UPDATE: click here for link to company - look for 'transwave converters' (this is what
I use)
[Edited on 23/1/04 by David Jenkins]
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paulf
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| posted on 23/1/04 at 10:47 PM |
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This sounds like a bridgeport mill, I know someone who has one converted to single phase by the use of a couple of capacitors. The comercially
available phase converters are expensive but if it is possible to add a capacitor to each individual motor to allow them to run on single phase with a
slight loss of efficency.
Try a search for phase converters and capacitors, I will try and get more details of the machine I know of.
I think the User of a seperate large 3 phase motor is also possible without a converter, the single phase suply is conected across two terminals and a
three phase suply is taken from all three, the power is then turned on and the motor spun by a length of rope to make it start on single phase. it
then runs as a motor generator an supplys the extra phases.Maybe not a recomended idea but could be worth a try if you can find a large three phase
motor.
Paul.
quote:
Originally posted by Carl.H
not easy flange mounted so hard to get hold of, but replacing the motors the easiest way
thanks
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stephen_gusterson
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| posted on 23/1/04 at 10:58 PM |
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ebay has at least one 2kw single to 3 phase converter at the moment - about 120 quid tho...
atb
steve
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Carl.H
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| posted on 24/1/04 at 01:05 PM |
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It’s a beaver mill like a Bridgeport.
Ye paulf a bloke at work suggested using a capacitor across two of the connections I’ve tried this but so far the motor has just moved rapidly
backwards and forwards.
THANKS everyone for the ideas, advice looks like I’ve got a lot of research to do.
Thanks again
Carl
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Alan B
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| posted on 24/1/04 at 01:37 PM |
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Don't know how much help this is, probably none..
I have a Chinese made "Bridgeport" type mill and that was 3PH too. I bought a phase convertor (about $80) and it works great (has done for
over 8 years). Maybe the electrical peple can throw some light on this, but it seems over here most houses get to separate live lines each of 110v,
but they are different phases (giving around 220v between them)(almost like two phase if such a thing exisited) anyway it seems that from the two
phases it is easy to manufacture a third one....of course with some power loss...
My lathe is 10HP and that runs off a phase convertor too...one I made from a kit....
As I say, probably irrelevant..
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dblissett
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| posted on 24/1/04 at 04:58 PM |
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3 phase
try rs componets they have some of the best prices for single phase inverters
you can use one inverter to drive all three motors at the same time but you will have to ad up all three kw ratttings and get a bigger inverter
you can run a three phase motor with a capacitor the problem is it will only give you about 60% torque
i work for a company that is involved with inverters and stock motors
so if i can help get in touch
cheers dave
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Carl.H
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| posted on 24/1/04 at 05:17 PM |
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hi dblissett
there is a Siemens inverter on ebay but it looks a little complicated to set up, do you now if this will work and how hard it would be to use.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2588918987&category=4660&rd=1
cheers Carl
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stephen_gusterson
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| posted on 25/1/04 at 12:25 AM |
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alan
the usa is different.
you have a shyte electrical system. turn on a hair dryer in a bathroom and the lights dip.
USA sockets are 10a at 110v. Im told they are individually fuesd at the box. that compares to our 240 at 13a - and there is actually 30a coming to the
socket itself.
cos american mains is so low powered, americans also have, as you say, two phases to the house for high current items such as cookers. Connecting
across two phases give higher voltage - in the uk two phases give 415 volts.
however, houses only get one phase. three phase is in the street, but its split somehow between properties to share the load. you cant get extra
phases in a uk house without major diggin work!
atb
steve
quote:
Originally posted by Alan B
Don't know how much help this is, probably none..
I have a Chinese made "Bridgeport" type mill and that was 3PH too. I bought a phase convertor (about $80) and it works great (has done for
over 8 years). Maybe the electrical peple can throw some light on this, but it seems over here most houses get to separate live lines each of 110v,
but they are different phases (giving around 220v between them)(almost like two phase if such a thing exisited) anyway it seems that from the two
phases it is easy to manufacture a third one....of course with some power loss...
My lathe is 10HP and that runs off a phase convertor too...one I made from a kit....
As I say, probably irrelevant..
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malcolmstoddart
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| posted on 25/1/04 at 01:12 PM |
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RS is good start for invertors and the like but could try Nord gear, use them a lot at work and do all the hard work for you,leaving you to install it
and pay the bill, remember that the flange section of the motor is separate and costs next to nowt to buy..
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dblissett
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| posted on 25/1/04 at 01:20 PM |
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inverter
i will look at work to see if we have a old/cheap one do you want to run all three motors at the same time=bigger invetrer
or one at a time=cheaper
i looked at the siemens one to late oh and i used to work for them
good luck dave
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stephen_gusterson
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| posted on 25/1/04 at 03:22 PM |
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i think the 3 motors would be a bit of a killer in cost.
a 3 phase converter of some site seems more economic....
atb
steve
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Carl.H
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| posted on 25/1/04 at 03:45 PM |
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Hi all thanks for all the advice . I’ll be ringing round a lot of places tomorrow to see what I can get.
I’ve been told I need three separate inverters because the 2hp spindle motor needs to be reversed.
The 0.75hp vertical feed motor needs to be reversed, turned on/off separately.
The 0.33hp horizontal feed motor needs to run constantly in the same direction (it has a gear box to reverse it).
Apparently if I wire all these up to one inverter and turn a motor on/off or reverse it the inverter will be damaged .
Oh and did I mention how much I hate electrics 
I drink to make other people interesting.
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DEAN C.
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| posted on 25/1/04 at 08:00 PM |
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Hi, surely you can use a reversing switch to reverse the phases to reverse the 0.75 motor.
I use a Power Capacitors phase converter for my Colchester lathe and I've wired the suds pump to run through a seperate switch but only when the
main motor is running,ie .it takes it's feed from the large motor terminals,this works fine.
My advise would be to phone this company up,they are very helpful,and i've run mine for about 9 years with no trouble at all.
I did touch 2 lives when I was first installing it and blew a unit inside,Power capacitors sent a new unit the next day free of charge with a detailed
instructions how to fit the part.
DEAN............
Once I've finished a project why do I start another?
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Carl.H
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| posted on 25/1/04 at 09:12 PM |
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Think the bloke I was talking to may have been trying to sell me another inverter (cheeky git).
Hi Dean can you reverse the motor and still have the coolant pump going the right way?
I think the bloke I spoke to was saying that if you change the load on inverter by turning another motor on after you've started the first this
would damage it but I don’t know.
Don’t suppose you’ve got the company’s phone number
Thanks, Carl
I drink to make other people interesting.
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dblissett
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| posted on 26/1/04 at 08:06 PM |
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inverters
hello carl you cant switch the output from a inveter while its running you will blow the caps in it
my advise would be put a capacitor on the suds pump because you will probably get away with it
and get one inveter to drive the spindle
you can reverse the motor from the keypad on the inverter dont use any type of switch between the motor and inveter
as this can blow the inverter
they are best wired direct from the inveter to the motor
ps single phase suds pumps are dirt cheap but the bridgeport drive motors are a bit none standard/costly
good luck dave
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David Jenkins
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| posted on 26/1/04 at 10:17 PM |
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It was Power Capacitors that told me about running the pilot motor - they even sent me a wiring diagram.
What this does is stabilise the 3 phases, so that you can switch motors on and off as you please without screwing up the converter output.
As I said earlier - give them a call, they're very helpful (number is further up the topic).
rgds,
David
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Carl.H
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| posted on 27/1/04 at 02:49 PM |
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Thanks
not paying enough attention
I drink to make other people interesting.
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