220 V 3ph to 440V 3ph
ferrofab
interested in getting a machine that is wired for 440V 3ph only. I'm
guessing the machine has a main motor drive of about 1-1/2 hp with
transformers for control voltages. What do you think the best solution
is to power this machine? Transformer? Try to get a new motor (it is a
2-speed), Rewire the existing motor? I have normal household 220 as my
starting reference.
* Sent from RemarQ http://www.remarq.com The Internet's Discussion Network *
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Peter
>>
What do you think the best solution is to power this machine? Transformer? Try
to get a new motor (it is a 2-speed), Rewire the existing motor? I have normal
household 220 as my starting reference.
>>
Simplest is a three phase transformer after your rotary converter
More complex is step-up of your single-phase to 440 volts and then do the
(rotary) conversion at 440 volts.
The latter will be expensive as capacitors rated for nearly 700 volts will be
required.
A converter operating on 240 volts needs capacitors rated at about 370 volts.
KD6JDJ
>I currently create 220 3ph using a rotary phase converter. I am
>interested in getting a machine that is wired for 440V 3ph only. I'm
>guessing the machine has a main motor drive of about 1-1/2 hp with
>transformers for control voltages. What do you think the best solution
>is to power this machine? Transformer? Try to get a new motor (it is a
>2-speed), Rewire the existing motor? I have normal household 220 as my
>starting reference.
I know what I'd do to get the machine to work from a 220 vac single phase.
I'd open the 3 phase motor, and (hopefully) locate it's wiring leads and
reconnect them to operate on 220 vac 3 phase. Then your rotary converter will
work.
If it's wiring leads arent marked, it may be a little work to determine how
to reconnect them for 220 vac. It may be that the 440vac 3 phase motor doesnt
have the windings which will allow it to be reconnected for 220 vac. Then, I
guess it would be necessary to locate 3 transformers and wire them to make 440
vac 3 phase from your rotary converter.
Jerry
Fitch R. Williams
>What do you think the best solution is to power this machine? Transformer? Try
>to get a new motor (it is a 2-speed), Rewire the existing motor? I have normal
>household 220 as my starting reference.
>>>
>
>Simplest is a three phase transformer after your rotary converter
>
>More complex is step-up of your single-phase to 440 volts and then do the
>(rotary) conversion at 440 volts.
>
>The latter will be expensive as capacitors rated for nearly 700 volts will be
>required.
>
>A converter operating on 240 volts needs capacitors rated at about 370 volts.
Having talked two folks through this process, I have to say I
respectfully disagree with about everything you said except the
capacitor voltage ratings used at 480V.
The single phase step up transformer is much easier to find and for a
novice to get wired correctly.
The used capacitors at 480V only need be 25% of the uF rating of those
required at 240V. Both folks managed to get the capacitors for free
from an industrial air conditioning dealer. Capacitors for a 3hp
idler are going to be quite small.
Run caps are used as required to make the starting cap.
PF correction caps and the main contactor are placed across the line
on the low voltage side of the converter.
Work real fine, last long time.
Fitch
In So. Cal.
The FAQ for RCM is: http://w3.uwyo.edu/~metal
Metal Web News at http://www.mindspring.com/~wgray1/
The "Drop Box" is at http://www.metalworking.com/
Eastburn
The cores have to be as one - and the windings 'interact' magnetically.
In fact that is how Star and twisted star patterns are made ...
Martin
--
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder
Martin Eastburn, Barbara Eastburn
@ home on our computer old...@pacbell.net
mull...@advinc.com
peter...@aol.communicate (Peter) wrote:
> Simplest is a three phase transformer after your rotary converter
>
> More complex is step-up of your single-phase to 440 volts and then
> do the (rotary) conversion at 440 volts.
>
> The latter will be expensive as capacitors rated for nearly 700 volts
> will be required.
I don't understand this. A rotary converter does not require
any capacitors at all.
Jim
Sent via Deja.com http://www.deja.com/
Before you buy.
dougra...@compuserve.com
> I currently create 220 3ph using a rotary phase converter. I am
> interested in getting a machine that is wired for 440V 3ph only. I'm
> guessing the machine has a main motor drive of about 1-1/2 hp with
> is to power this machine? Transformer? Try to get a new motor (it is a
> 2-speed), Rewire the existing motor? I have normal household 220 as my
> starting reference.
>
This is easy and relatively inexpensive. Get two single phase 220
to 440 transformers and wire them in an "open delta" configuration.
Single phase transformers are a dime a dozen compared to the three
phase type. Check with an outfit that deals in used transformers, my
last hookup cost less than fifty bucks for two properly sizes
transformers to run a 1.5hp motor.
I don't have the open delta wiring connection at hand, but any dealer
in transformers will have it. It's widely used in industrial
applications. I've been running 3 machines with dual speed 440V-only
motors this way for years from my 220 three phase converter.
Doug
Peter
Fitch R. Williams replies ...
>>
Having talked two folks through this process, I have to say I respectfully
disagree with about everything you said except the capacitor voltage ratings
used at 480V.
>>
Fitch, as the acknowledged expert on these matters, I will, of course, defer to
you.
BTW, the responder who claimed that a rotary converter requires *no* capacitors
at all should review the countless posts on rotary converters appearing in this
NG. All designs require at least one capacitor in order to achieve even
mediocre performance. The very best performers (namely, those designed after
Fitch's designs) require three running capacitors and one starting capacitor.
Peter
>>
I don't think two or 3 transformers would work for stepping up/down 3 phase.
The cores have to be as one - and the windings 'interact' magnetically.
In fact that is how Star and twisted star patterns are made ...
>>
One three-phase transformer or three single-phase transformers, sized
appropriately, perform identically.
dougra...@compuserve.com
> I don't think two or 3 transformers would work for stepping up/down 3
phase.
>
As I said, you connect *TWO* (that's 2) single phase transformers in
an open delta configuration to accomplish the boost from 220 to 440.
This is not speculation, it's routinely done and recommended by
transformer manufacturers. I've been running this way for at least 15
years.
Both Acme and Tierney transformer companies show the open delta
connection diagrams in their catalogs. An engineer at Tierney showed
me this after I gagged on the price of a three phase booster
transformer.
Gary Coffman
>I don't think two or 3 transformers would work for stepping up/down 3 phase.
You better tell the power companies that, because they think 3 transformers
work just fine. They use them all the time. Our transmitter site (316 kW) is
supplied via 3 transformers wired in an ordinary delta configuration. Our
studio plant only uses 2, in an open delta configuration.
Gary
Gary Coffman KE4ZV | You make it |mail to ke...@bellsouth.net
534 Shannon Way | We break it |
Lawrenceville, GA | Guaranteed |
mull...@advinc.com
peter...@aol.communicate (Peter) wrote:
> BTW, the responder who claimed that a rotary converter requires *no*
> capacitors
> at all should review the countless posts on rotary converters
This is, amazingly enough, not required. I would, instead, simply
visit my basement and review myself making some chips with my
machines which are powered by a converter that consists of a 5 hp
Allison Chalmers idler motor. Even the pony motor that starts it
is a *repulsion-induction* type which has nary a microfarad in it.
It works just fine, and although the PF is poor, the reactive currents
that flow do not trip the 15amp breaker that powers it, nor do they
spin the meter on the side of the house. Its "performance" running
both lathe an mill leaves nothing to be desired.
So my advise to the original poster would be to consider the following
setup: 2x step-up transformer, idler motor connected for 440 V, and
run your machines that way. No capacitors needed. Although I
would run this by Fitch for his opinions as he might see a hole in
it that I miss.
And there is no need for me to review the converter posts anyway,
as I have eagerly devoured every one when it was first posted.
Jim
mull...@advinc.com
kd6...@aol.com (KD6JDJ) wrote:
> I'd open the 3 phase motor, and (hopefully) locate its wiring leads
>and
> reconnect them to operate on 220 vac 3 phase.
Jerry, this is probably not possible with this motor. He mentioned
that it is a _2_ speed motor. Often 2 speed three-phase motors
are constructed by a trick called pole-changing, whereby the
windings are configured externally (by a drum switch) into either
star or delta setup. This causes so many leads to exit the motor
to the drum switch that the manufacturer cannot center tap each
winding to allow dual voltage use.
At least, I have never seen a hardinge two speed motor wired dual
voltage like that. I think Garry was attempting to get one of these
re-wound from 440 to 220 at a shop.
james askew
would require about 50% more current capacity in each.
Jim
KD6JDJ wrote:
>
> >From: ferrofab
>
> >I currently create 220 3ph using a rotary phase converter. I am
> >interested in getting a machine that is wired for 440V 3ph only. I'm
> >guessing the machine has a main motor drive of about 1-1/2 hp with
> >transformers for control voltages. What do you think the best solution
> >is to power this machine? Transformer? Try to get a new motor (it is a
> >2-speed), Rewire the existing motor? I have normal household 220 as my
> >starting reference.
>
Paul Amaranth
>In article <20000407130743...@ng-cq1.aol.com>,
> peter...@aol.communicate (Peter) wrote:
>
>> Simplest is a three phase transformer after your rotary converter
>>
>> More complex is step-up of your single-phase to 440 volts and then
>> do the (rotary) conversion at 440 volts.
>>
>> The latter will be expensive as capacitors rated for nearly 700 volts
>> will be required.
>
>I don't understand this. A rotary converter does not require
>any capacitors at all.
>
>Jim
>
Key word is require. It works without them; it works better with them.
Without caps the voltages on the generated phases are likely to be ~210-220
compared to 240-245 from the line. Using correctly chosen caps you can
get the voltages on all 3 phases close under a given load.
Paul
--
Paul Amaranth | Rochester MI, USA
Aurora Group, Inc. | Systems & Software
pa...@AuroraGrp.Com | Unix / Windows / NT
Fitch R. Williams
>Its "performance" running
>both lathe an mill leaves nothing to be desired.
Jim,
I agree. Folks have used unturned pony motor started idlers for
years. Two or three on the NG do that. It works for them. It works
for you.
Getting even more elementary, I've even started mine by flipping the
shaft (when it had one) with my hand and then pushed the plug into the
wall socket - it groaned but it started. That was your bare bones
elementary converter. Line cord and idler motor. Period. Nothing,
not even a switch, to complicate it. I don't recommend that
configuration to anybody for the simple reason that if there is a
power failure it will just sit there and get hot until the breaker
pops unless you unplug it. I prefer that they shut off and stay off
during a power failure.
However, having said that, if you haven't run your lathe on real three
phase, you may not know how much better it could run. OTOH, if you
don't take heavy cuts and seldom use the top speed, and never plug
reverse doing metric threads you may never notice the difference.
On my gear head lathe, the difference in performance between the bare
idler and the tuned one is definitely noticeable - same for the mill.
KD6JDJ
>Jerry, this is probably not possible with this motor. He mentioned
>that it is a _2_ speed motor.
Jim
Thats what happens when you (I, in this case) start answering before you (I,
in this case) read.
Actually, I reread the post after I answered and realized how unlikely it was
that a 2 speed would have room enough for all thoes leads.
This is not the first time I've posted stupid errors in my responses ---
BUT, I hope it is my last.
Thanks for the politeness in your post.
Jerry
DoN. Nichols
<dougra...@compuserve.com> wrote:
> Eastburn <old...@pacbell.net> wrote:
>> I don't think two or 3 transformers would work for stepping up/down 3
>phase.
>>
>
> As I said, you connect *TWO* (that's 2) single phase transformers in
>an open delta configuration to accomplish the boost from 220 to 440.
>This is not speculation, it's routinely done and recommended by
>transformer manufacturers. I've been running this way for at least 15
>years.
I agree that for normal three-phase these should work well.
However, I also feel that the two-transformer "open delta"
configuration as a load on the typical rotary converter may sufficiently
unbalance it to cause problems. I don't know for sure whether
sufficient tinkering with the run caps can fix this or not, but I would
not want to do it feeding two different loads from the same converter
and step-up.
Good Luck,
DoN.
--
Email: <dnic...@d-and-d.com> | Voice (all times): (703) 938-4564
My Concertina web page: | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
GaryH82012
>voltage like that. I think Garry was attempting to get one of these
>re-wound from 440 to 220 at a shop.
>
>Jim
Thanks for remembering me. I decided against having the 440-only motor rewound
for 220 because the price I was quoted was $550. I called Paramount Machinery
looking for a 220 volt motor in the same frame size and Norm had one at a good
price. It turned out to be a bit of a project. Most of the leads had been
damaged from heat or being connected wrong and I spent many hours with an
underpowered soldering iron adding new wire in hard to reach places. Then I had
to make a chart of the resistance values of all the possible combinations of
the six wires and compare them to the same values in the old motor. (By the
way, the ohm measurements I got indicated approximately 10% of the resistance
of the same combinations in the 440 volt motor - it led me to wonder how is a
220 volt motor fundamentally different from a 440 volt motor?) This was to
avoid connecting the power incorrectly and damaging something. Also I needed to
make sure the new motor was wired exactly the same internally so it would
function the same when controlled by the forward/reverse and fast/slow drum
switches. Satisfied that the wiring was the same, I started it up and it
sounded like hell. $45 in new bearings later, it sounded pretty good. There is
an intermittant "growling" sound, but rpms are about 10% higher than nameplate
says (don't know why) so I think it's a keeper. By the way, Jim, there was
another Hardinge mill at the sale where I bought my UM model. I thought they
were identical when I first looked at them, so my bid was for "either one" at
$2600. It turned out to be a real lesson in how you overlook important details
when inspecting machinery you aren't familiar with. The machine I got was
better equipped because it came with the horizontal spindle and the vertical
head, but it was way more abused, had makeshift knobs and handles, a very crude
paint job and a 440-only motor. The other mill was pristine by comparison and
had a 220/440 motor, but set up for vertical only. Now that I've had some
experience working on, not with, the machine, I am amazed at how much I
overlooked. With a screwdriver and a flashlight, plus some knowledge, I could
have made a much smarter buy. I'm putting in a bid on the second machine
immediately. Gary Hastings
KD6JDJ
>>an open delta configuration to accomplish the boost from 220 to 440.
>I agree that for normal three-phase these should work well.
>
> However, I also feel that the two-transformer "open delta"
>configuration as a load on the typical rotary converter may sufficiently
>unbalance it to cause problems. I don't know for sure whether
>sufficient tinkering with the run caps can fix this or not, but I would
>not want to do it feeding two different loads from the same converter
>and step-up.
>
> Good Luck,
> DoN.
DoN
How about if the two transformers (to be 'open delta' connected) were
connected so the 'phantom' transformer is the 220 vac input line.
I would have guessed that the added transformers could help balance the 3
phase.
I realize that I'm in a minority group about the need to include balance
capacitors. But, I have seen two machine shops run from rotary converters that
were "rope started" in the morning, and allowed to spin all day. Each shop had
several mills and lathes that saw intermittant use.
Jerry
Bachman
hookup but so far no clues. Pleas explain.
Bob
DoN. Nichols
GaryH82012 <garyh...@aol.com> wrote:
[ ... replacing 440V 3-phase 2-speed motor with similar 220V
version ... ]
>the six wires and compare them to the same values in the old motor. (By the
>way, the ohm measurements I got indicated approximately 10% of the resistance
>of the same combinations in the 440 volt motor - it led me to wonder how is a
>220 volt motor fundamentally different from a 440 volt motor?)
Well ... you would have fewer turns for the lower voltage --
about half the number, so there would be more room on the poles. Then
you would have the gauge of the wire larger, to handle the extra current
(double) which would fill up the pole pieces again. Half the turns =
half the resistance. Increase the wire size to twice the cross-section,
and you halve the resistance again, so you've got 1/4 the resistance.
It is possible that this was wound with even heavier wire, which could
lower the resistance even more.
> This was to
>avoid connecting the power incorrectly and damaging something. Also I needed to
>make sure the new motor was wired exactly the same internally so it would
>function the same when controlled by the forward/reverse and fast/slow drum
>switches. Satisfied that the wiring was the same, I started it up and it
>sounded like hell. $45 in new bearings later, it sounded pretty good. There is
>an intermittant "growling" sound, but rpms are about 10% higher than nameplate
>says (don't know why)
Does the nameplate happen to mention the frequency? If it is a
50Hz motor, it will have fewer turns, and heavier gauge wire, so that
could account for the lower resistance, and should result in 20% higher
speed than the nameplate suggests.
Enjoy,
Gary Hallenbeck
A question in this vein. A friend of mine has a Hardinge lathe that is 440.
He ran it in our shop on 220 using a transformer so he already has a 220 to
440 step up transformer. He now wants to run it at home so he needs a phase
converter. Are there any problems inherent in stepping up the output from a
phase converter?
Gary Hallenbeck
Fitch R. Williams <frwi...@ptw.com> wrote in message
news:us3tesci38jpk4le4...@4ax.com...
> peter...@aol.communicate (Peter) wrote:
>
> >What do you think the best solution is to power this machine?
Transformer? Try
> >to get a new motor (it is a 2-speed), Rewire the existing motor? I have
normal
> >household 220 as my starting reference.
> >>>
> >
> >Simplest is a three phase transformer after your rotary converter
> >
> >More complex is step-up of your single-phase to 440 volts and then do the
> >(rotary) conversion at 440 volts.
> >
> >The latter will be expensive as capacitors rated for nearly 700 volts
will be
> >required.
> >
> >A converter operating on 240 volts needs capacitors rated at about 370
volts.
>
> Having talked two folks through this process, I have to say I
> respectfully disagree with about everything you said except the
> capacitor voltage ratings used at 480V.
>
> The single phase step up transformer is much easier to find and for a
> novice to get wired correctly.
>
> The used capacitors at 480V only need be 25% of the uF rating of those
> required at 240V. Both folks managed to get the capacitors for free
> from an industrial air conditioning dealer. Capacitors for a 3hp
> idler are going to be quite small.
>
> Run caps are used as required to make the starting cap.
>
> PF correction caps and the main contactor are placed across the line
> on the low voltage side of the converter.
>
> Work real fine, last long time.
>
Eastburn
Sure enough - three transforms on a pole. I think the trick is they
Start with three phase and step down(up) from phase shifted power.
One can go from single phase and generate three (albeit not efficient).
But that has to be in one core. The core gives the phase shifts for the phases.
Martin
--
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder
Martin Eastburn, Barbara Eastburn
@ home on our computer old...@pacbell.net
Gary Coffman wrote:
>
> On Fri, 07 Apr 2000 22:18:31 -0700, Eastburn <old...@pacbell.net> wrote:
> >I don't think two or 3 transformers would work for stepping up/down 3 phase.
>
Eastburn
But we used three, 5, 7, 9 and funky 11 phase as examples for industrial
uses. Can't do that stuff with multiple transformers.
If you read my post before this - you will see I looked it up tonight
and gave the source.
Schematics in books don't show the whole fact.
Generally I think you will ok - but the inverted V with a loss of phase
won't generate the third phase magically.
Eastburn
a 2000 sq. ft house. All custom wound for the specific Alternator(a.k.a. generator).
The power house generates three phase and the transformers are simply
transforming the voltage, not generating or shifting phase.
Like I said earlier - you have to start out with 3 phase and then you are ok.
Not the best - Still think Inverted V might not work.
Martin
--
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder
Martin Eastburn, Barbara Eastburn
@ home on our computer old...@pacbell.net
"Orrin B. Iseminger" wrote:
>
> Hmmmm. I might be mistaken, but I spent 23 years in the hydro industry. At our plants
> the bigger transformers were always separate; one transformer for each phase.
>
> Orrin
>
> In article <38EEC127...@pacbell.net>, old...@pacbell.net says...
> >
> >I don't think two or 3 transformers would work for stepping up/down 3 phase.
> >
> >The cores have to be as one - and the windings 'interact' magnetically.
> >In fact that is how Star and twisted star patterns are made ...
> >
Peter
>>
Without caps the voltages on the generated phases are likely to be ~210-220
compared to 240-245 from the line. Using correctly chosen caps you can get the
voltages on all 3 phases close under a given load.
>>
Ideally, a properly sized and tuned rotary converter can be made such that the
"manufactured phase" is no more than 110 percent of line-line coltage, when
unloaded, and no less than 90 percent of line-line voltage, when fully loaded.
AFAIK, this high degree of performance cannot be achieved without capacitors.
Orrin B. Iseminger
KD6JDJ
>OK, I give up. Kept hoping someone would explain 'open delta'
>hookup but so far no clues. Pleas explain.
>
>Bob
Bob
Can you visualize how to connect 3 transformers across a 3 phase circuit in a
delta configuration?
The 3 transformers will have a total of 6 primary leads, 2 for each
transformer.
The leads of the 3 transformers are connected so that their primary windings
form the shape of a delta.
If one of the transformers was removed, the shape would no longer be 'delta'.
But the voltage across that pair of terminals will still have voltage across
them. And the phase of the voltages at the other terminal will be controled by
the input 3 phase line.
I dont present this as a flawless explanation. But I think it is accurate,
and will be glad to clear up any misleading statements
Jerry
mull...@advinc.com
frwi...@ptw.com wrote:
>
> However, having said that, if you haven't run your lathe on real three
> phase, you may not know how much better it could run. OTOH, if you
> don't take heavy cuts and seldom use the top speed, and never plug
> reverse doing metric threads you may never notice the difference.
I do plug reverse while threading, and the limit when cutting heavy
is leather belt slip. Although it's time for a new one, as it is
getting oil-soaked. I suspect one reason why this one works well
is it's a 5 hp motor idler running a 1 hp machine. I've considered
adding a drop-out contactor, but I never leave the shop while it
is running, and the cartrige fuses are 10 amps each. The line to
the panel board is number 12 wire and the breakers are 15 amps.
I suppose I should keep my eyes out for some capacitors to tune it,
but something else always keeps me busy.
mull...@advinc.com
garyh...@aol.com (GaryH82012) wrote:
> The machine I got was
> better equipped because it came with the horizontal spindle and the
> vertical head, but it was way more abused, had makeshift knobs and
> handles, a very crude paint job and a 440-only motor. The other mill
> was pristine by comparison and
> had a 220/440 motor, but set up for vertical only.
I don't understand what it is about these UM milling machines that
lead former owners to remove the handles and destroy them. Mine
came with handwheels made of (and I sh%t you not) welded re-bar.
This must be some kind of corollary to the law that says all used
motorbikes must be sold without a headlight and an incorrect tail light.
Just out of curiosity, you mention one with a dual-voltage motor.
Was that in fact a two speed, dual voltage motor, associated with
the hardinge vertical head, or maybe an M head that had been
grafted on?
Peter
>>
Hmmmm. I might be mistaken, but I spent 23 years in the hydro industry. At
our plants the bigger transformers were always separate; one transformer for
each phase.
>>
Certainly true of most of the older plants.
I was an EE at the largest municipal utility in the U.S.
All our old plants had three (four in exceptional cases; the fourth being a
"cold spare") single plase transformers in banks.
All our transmission was delta, as were most other utilities.
Many of our newer plants did have three phase transformers, however.
A typical transformer bank for a major commercial customer might have been
three 333 KVA transformers (1 MVA total) with 34.5 kV primary (delta) and
277/480 volts secondary (wye).
In such cases, the customer usually provided his own "dry type" transformers
for 120/240 volts (delta) or 120/208 volts (wye).
Gary Coffman
>Need not be so angry. I used to teach that stuff 30 years ago in college.
>But we used three, 5, 7, 9 and funky 11 phase as examples for industrial
>uses. Can't do that stuff with multiple transformers.
Why not? Seems to me you can always use one transformer per phase.
Fitch R. Williams
>One can go from single phase and generate three (albeit not efficient).
>But that has to be in one core.
Boy, I sure don't see any way to take one incoming single phase line
and generate usable three phase power from it using only transformers.
How is this done?
Peter
Fitch R. Williams replies ...
>>
Boy, I sure don't see any way to take one incoming single phase line and
generate usable three phase power from it using only transformers.
How is this done?
>>
Can't be done (single phase to polyphase).
Phase conversions which can be accomplished solely by use of transformers
include:
1) Three phase to two phase,
2) Two phase to three phase,
3) Three phase to single phase, and
4) Two phase to single phase.
In order to effect phase conversions, one must have access to power which
differs by other than 0 degrees or 180 degrees.
Three phase meets this requirement by providing 120 degrees difference between
phases.
Two phase meets this requirement by providing 90 degrees difference between
phases.
The inability to make phase conversions from single phase becomes apparent when
one attempts to construct a phase diagram. Any and all vectors which are
developed and then summed will still be either 0 or 180 degrees, the same phase
one started with. Therefore there can no phase conversion.
Eastburn
Have you seen 7 and 9 phase star patterns ? They are like twisted Y's.
Each arm has a winding at a different phase relationship to the main arm.
These are all on on nasty to wind core.
If they can generate these complex phase angles for Canning machines -
Not those that fill cans, but those that punch out the cans e.g. empty Beer cans.
Those are driving complex motors that are smooth in action. They are
like the V8 to the V4 - the V4 almost shakes the car in the process -
the V8 purrs, having multiple cylinders in all phases of movement.
Eastburn
In a single core an intersected double 8 e.g. three holes -
the three primaries interact with all three secondaries - while the close winding -
that in the same loop has most generation capability.
If the three transformers are indead three - as the power company sometimes does -
mostly on poles - this phase aid flux can't occur.
So the two are different in subtle ways - depending on loss of or sagging of a phase.
Eastburn
I have seen two phase delivered to farms and ranches - then they run inverted V
on the primary, delta on the secondary to run milking, cooling etc. and other
fun equipment on ranches.
One can get all sort of phase angles in transformer cores.
One gets poly phase from having separate cores for the multiphase and the secondaries
are jointly wound across multiple cores with the primary on a single core.
Some here don't read so close - I seem to recall real three phase far better than
generated or pseudo three.
Eastburn
points between. The mains just off the turbine are three phase. Custom wound.
We talk about $1M per transformer in the 60's.
I think yard transformers are singles. Because users / neighborhoods
can burn out a single - e.g. overheat it - ...
Peter
>>
Never heard of two phase at 90 degree. Three or 4 wire two phase?
>>
The NEC shows FIVE different protective methods for two phase systems.
There are three wire, four wire and five wire two phase distribution systems.
Two phase is or was available in Philadelphia, but it has generally been
abandoned elsewhere.
Peter
>>
Have you seen 7 and 9 phase star patterns ? They are like twisted Y's.
Each arm has a winding at a different phase relationship to the main arm.
These are all on on nasty to wind core.
>>
Are you referring to so-called "zig zag" wound transformers?
Fitch R. Williams
>Have you seen 7 and 9 phase star patterns ?
No, it would sure have to have smooth torque though.