I’m hoping someone out there might have some experience they would
be willing to share privately or to the group regarding a step up
converter to go from single phase to three phase. I’m not sure if I
need a static or rotary version and what size. I will need to have
someone install it but would like to know a little in advance.
Thanks
Charlie
Charlie,
You might want to post this question to a group of metal artists
with a e mail only “site” called the Sandbox. Signup info is:
sandbox mailing list
http://www.ganoksin.com/gnkurl/ep81k5
I know for a fact you will get some help/ideas on this as these
folks work mostly in bigger metal pieces and some have and use
converters or at least have used them in the past.
john dach
Hi Charlie,
What you need depends on what you’re trying to run, and what you’re
trying to do with it.
There are a couple of different options, depending on application.
(A) rotary converters. Expensive, but best for things where you need
‘real’ 3 phase, and you have a machine that’s more than just a
motor.
(B) static converters. Cheap, but the legs aren’t usually perfectly
balanced, and not quite as high rated as a rotary. Good for things
like sanders, or blower motors
(C) VFD’s. (Variable Frequency Drive) A modification of a static
converter, these will take a 3Ph motor, and make it infinitely
variable. You lose some torque on the low end, and it will play hell
with anything other than a motor, but can be very useful indeed
for motor only setups.
Size depends on startup currents. There are ‘hard starting’ things
like lathes and air compressors, versus ‘easy starting’ things like
belt sanders. What you have selects what you need. That’s where you
need to talk to the engineers at whatever company you end up going
with for whatever product. They’ll know best what you need.
I’ve had good luck with Temco, that’s the place where I got the
rotary that runs my big lathe. That’s got a 5HP motor in it, but
being a lathe, it needs a 7HP rotary to get it started.
For whatever that all was worth.
Brian
Static converters are relatively inexpensive to buy but, in general,
you will only get about 1/2 the power from your 3 phase motor.
Rotary converters are expensive to buy but usually cheap to build
and will give you almost full power from your motor.
A little ‘googling’ for “home built rotary 3 phase converter” should
turn up some info.
Here’s one link: Phase Converters
alonzo
Charlie I had the same problem here in Panama. I found a electrician
that took a 2 hp electric 220v elect motor and rewired it to produce
the 3 phase I needed. Works great. I put it in a noise proof box and
am very happy. You can google how to convert 2 phase to 3 phase and
get the wiring diagrams…
I'm hoping someone out there might have some experience they would be willing to share privately or to the group regarding a step up converter to go from single phase to three phase. I'm not sure if I need a static or rotary version and what size. I will need to have someone install it but would like to know a little in advance.
A number of years ago, I found what seemed a fantastic deal on ebay
for an older Cavalin power rolling mill. Not only got it for a
fraction of what they used to sell for new, but the seller knew a
trucker coming this way, so the normally high shipping costs too,
were reasonably low. Great, until I got it into the shop and
discovered it wouldn’t run as expected, due to it needing 3 phase
power (the seller hadn’t know this, and there isn’t an obvious
external label showing it. I had to open the base cover and look at
the motor to find out. Anyway, in looking for ways to convert it, I
happened to talk to Matt (I think that was his name) Durston, who as
you know make wonderful rolling mills. He said the clear way to go
was not the usual converters, but what he called a rectifier. That,
he said, is what they install in their mills, regardless of what
power source the mill is plugged into, since being able to run the
motor itself internally on 3 phase gave better perfomance, plus that
method gave full variable speed control. The things work by first
taking the single phase AC power and rectifying it, then feeding that
to an oscillator running much higher frequency than the normal 60hz.
The resulting high frequency AC is then converted electronically to
3phase, and converted back down to 60hz. Or something like that. I’m
guessing that anyone here with real electronics knowledge just fell
off their chair laughing, but that description is the best I can do
without going back and looking up the documentation. The device,
which I just bolted to the outside of the rolling mill base, is
fairly small, about a six inch cube or thereabouts, with touchpad
controls for on/off and speed. Works fine. Memory is that it cost a
couple hundred bucks, but I might be recalling that wrong, and of
course by now the price won’t be the same anyway. Hope that helps.
Peter Rowe
Hi Peter,
They’re called “VFD” units on this side of the pond. So far as I
understand them, you got the basics right.
The cool thing about them is that for small motors (sub 3/4hp) you
can get units that will run a 220 3Ph motor on 115 VAC house
current.
That’s what I’m thinking about doing with one of the little Ames
lathes I just picked up. Full variable speed for under $200.
Ah, the joys of non-household electrics.
Brian
Google VFD (variable-frequency drive) and you may find some good
about how to solve this problem. Good luck. Rob
Rob Meixner
They're called "VFD" units on this side of the pond. So far as I understand them, you got the basics right. The cool thing about them is that for small motors (sub 3/4hp) you can get units that will run a 220 3Ph motor on 115 VAC house current.
They are actually inverters, they take the 115 or 220 VAC turn it
into DC and then chop that into 3 Phase AC. They work great for many
motor applications. Air compressors lathes and other loads that are
not heavily loaded on startup work fine things like hydraulic pumps
are not as happy on them. My Haas Lathe has a 7 hp 3 Phase motor
that runs off of 220 VAC single phase with an internal inverter in
the Haas control cabinet. That is about the upper limit of the size
you can run on them in 220 volt single phase configuration, larger
inverters want 3 phase input. I also had a rotary converter for a
1.5 hp 3 phase hydraulic pump. It worked quite well but needed to be
a 5 hp unit to run it, my older 3 hp one would bog down when trying
to start it. So talk to the rotary manufacturer to see how big a
motor for what type of use they will start.
James Binnion