Now that I'm getting some transformers to buck the voltage from my
phase converter I need to determine whether the output is wired wye or
delta. I think it's delta. but since it's a phase converter I just
don't know and need to be sure. According to the Square D website the
wiring is different between delta and wye when using the buck xmfrs.
Delta only needs two xmfrs for example. So how do I determine what I
have? I do know that leg to leg voltage is the same but that leg to
neutral for the manufactured leg is not. The two lines supplied by the
power company measure 124 volts to neutral and the manufactured leg to
neutral is 230 volts.
Thanks,
Eric

On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure. According to the Square D website the

wiring is different between delta and wye when using the buck xmfrs.

Delta only needs two xmfrs for example. So how do I determine what I

have? I do know that leg to leg voltage is the same but that leg to

neutral for the manufactured leg is not. The two lines supplied by the

power company measure 124 volts to neutral and the manufactured leg to

neutral is 230 volts.

Thanks,

Eric

Leg to leg voltages should around 240 volts.

The generated leg should make the system look like an open Delta.

But the supply being Delta or Wye will not affect the transformers.
The transformers can however be wired int Delta or Wye....

IOW, you have a supply. It can be Delta or Wye.

Then you have the Buck/Boost transformers.
They can be wired in Delta or Wye.

Don't confuse the two things.

On Fri, 2 Nov 2012 09:34:08 -0700 (PDT), Cross-Slide
wrote:

On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure. According to the Square D website the

wiring is different between delta and wye when using the buck xmfrs.

Delta only needs two xmfrs for example. So how do I determine what I

have? I do know that leg to leg voltage is the same but that leg to

neutral for the manufactured leg is not. The two lines supplied by the

power company measure 124 volts to neutral and the manufactured leg to

neutral is 230 volts.

Thanks,

Eric

Leg to leg voltages should around 240 volts.

The generated leg should make the system look like an open Delta.

But the supply being Delta or Wye will not affect the transformers.
The transformers can however be wired int Delta or Wye....

IOW, you have a supply. It can be Delta or Wye.

Then you have the Buck/Boost transformers.
They can be wired in Delta or Wye.

Don't confuse the two things.
Well maybe I just don't understand. The Square D website has wiring
diagrams for both wye and delta SUPPLY according to my interpretation.
However, I'm pretty sure I have open delta.
Eric

wrote in message ...
Now that I'm getting some transformers to buck the voltage from my
phase converter I need to determine whether the output is wired wye or
delta. I think it's delta. but since it's a phase converter I just
don't know and need to be sure. According to the Square D website the
wiring is different between delta and wye when using the buck xmfrs.
Delta only needs two xmfrs for example. So how do I determine what I
have? I do know that leg to leg voltage is the same but that leg to
neutral for the manufactured leg is not. The two lines supplied by the
power company measure 124 volts to neutral and the manufactured leg to
neutral is 230 volts.
Thanks,


Consider it as being a delta system.

wrote in message ...
On Fri, 2 Nov 2012 09:34:08 -0700 (PDT), Cross-Slide
wrote:

On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure. According to the Square D website the

wiring is different between delta and wye when using the buck xmfrs.

Delta only needs two xmfrs for example. So how do I determine what I

have? I do know that leg to leg voltage is the same but that leg to

neutral for the manufactured leg is not. The two lines supplied by the

power company measure 124 volts to neutral and the manufactured leg to

neutral is 230 volts.

Thanks,

Eric

Leg to leg voltages should around 240 volts.

The generated leg should make the system look like an open Delta.

But the supply being Delta or Wye will not affect the transformers.
The transformers can however be wired int Delta or Wye....

IOW, you have a supply. It can be Delta or Wye.

Then you have the Buck/Boost transformers.
They can be wired in Delta or Wye.

Don't confuse the two things.
Well maybe I just don't understand. The Square D website has wiring
diagrams for both wye and delta SUPPLY according to my interpretation.
However, I'm pretty sure I have open delta.
Eric

http://www.contractortalk.com/attach...buck-boost.jpg


Eric it might be helpful if yiou link us to the applicable Square D conections diagram...

Also, strongly suggest that when testing any transformer connection, temporarily fuse the input side with a set of relatively low amperage fuses, say, 10 amps or so in order to protect the transformer for just in case you've made a serious mistake.

On 2012-11-02, Cross-Slide wrote:
On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure. According to the Square D website the

wiring is different between delta and wye when using the buck xmfrs.

Delta only needs two xmfrs for example. So how do I determine what I

have?

Leg to leg voltages should around 240 volts.

The generated leg should make the system look like an open Delta.

But the supply being Delta or Wye will not affect the transformers.
The transformers can however be wired int Delta or Wye....

IOW, you have a supply. It can be Delta or Wye.

Then you have the Buck/Boost transformers.
They can be wired in Delta or Wye.

But Buck/Boost transformers act sort of like an autotransformer.
There is no isolation between input and output so the voltages and phase
relationships are a bit weird with delta wiring -- *unless* you use only
two transformers and operate it as "open delta", and connect the low
side of the two together, so the boosts are balanced. If you connect
the third one in as well, you'll have weird things in terms of phase
relationships. Of course, the generated phase from a rotary converter
is already a little weird, so I guess that you can live with that. :-)

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Fri, 02 Nov 2012 11:27:48 -0700, wrote:

On Fri, 2 Nov 2012 09:34:08 -0700 (PDT), Cross-Slide
wrote:

On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure. According to the Square D website the

wiring is different between delta and wye when using the buck xmfrs.

Delta only needs two xmfrs for example. So how do I determine what I

have? I do know that leg to leg voltage is the same but that leg to

neutral for the manufactured leg is not. The two lines supplied by the

power company measure 124 volts to neutral and the manufactured leg to

neutral is 230 volts.

Thanks,

Eric

Leg to leg voltages should around 240 volts.

The generated leg should make the system look like an open Delta.

But the supply being Delta or Wye will not affect the transformers.
The transformers can however be wired int Delta or Wye....

IOW, you have a supply. It can be Delta or Wye.

Then you have the Buck/Boost transformers.
They can be wired in Delta or Wye.

Don't confuse the two things.
Well maybe I just don't understand. The Square D website has wiring
diagrams for both wye and delta SUPPLY according to my interpretation.
However, I'm pretty sure I have open delta.
Eric

Wait a minute - If you are starting with Residential 120/240V Single
Phase that's coming in too hot, you need ONE Buck-Boost on the input
to your phase converter to drop the voltage down to 240V.

Get the voltage right to the input of the phase converter, and let it
handle making the third leg at the right voltage.

Wye, Delta or Open Delta only count when you're getting the 3-phase
straight from the Power Company.

Most residential users with wells or elevators, or small Commercial
like a strip mall gets 120/240V Open Delta - One big transformer on
the pole for the 120/240 which is the bulk of your load, and a smaller
transformer next to it for the Wild Leg.

The Wild Leg usually measures ~190V to ground, gets tagged Orange so
you don't mess up and hook a 120V load to it. Because you hook up
there and Light bulbs and ballasts don't last long...

Full Delta is usually straight 240V or 480V - three equal sized
transformers.

Wye is either 277/480V or 120/208V - three equal sized transformers,
but all the commons are grounded and becomes the Neutral point.

-- Bruce --

On Fri, 2 Nov 2012 15:50:23 -0700, "PrecisionmachinisT"
wrote:


wrote in message ...
On Fri, 2 Nov 2012 09:34:08 -0700 (PDT), Cross-Slide
wrote:

On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure. According to the Square D website the

wiring is different between delta and wye when using the buck xmfrs.

Delta only needs two xmfrs for example. So how do I determine what I

have? I do know that leg to leg voltage is the same but that leg to

neutral for the manufactured leg is not. The two lines supplied by the

power company measure 124 volts to neutral and the manufactured leg to

neutral is 230 volts.

Thanks,

Eric

Leg to leg voltages should around 240 volts.

The generated leg should make the system look like an open Delta.

But the supply being Delta or Wye will not affect the transformers.
The transformers can however be wired int Delta or Wye....

IOW, you have a supply. It can be Delta or Wye.

Then you have the Buck/Boost transformers.
They can be wired in Delta or Wye.

Don't confuse the two things.
Well maybe I just don't understand. The Square D website has wiring
diagrams for both wye and delta SUPPLY according to my interpretation.
However, I'm pretty sure I have open delta.
Eric

http://www.contractortalk.com/attach...buck-boost.jpg


Eric it might be helpful if yiou link us to the applicable Square D conections diagram...

Also, strongly suggest that when testing any transformer connection, temporarily fuse the input side with a set of relatively low amperage fuses, say, 10 amps or so in order to protect the transformer for just in case you've made a serious mistake.
Here's the link to the Schneider Electric site:
http://static.schneider-electric.us/...7414CT0201.pdf
Square D was bought by Schneider. The diagram I think I need to use is
#5 on page 6. The xmfrs are the 1.5S46F model. I used table 15, page
19 to determine which wiring diagram to use. After looking at the
above link again I'm sure that open delta wiring is what I have and
need to use.
Eric

On 2 Nov 2012 23:00:40 GMT, "DoN. Nichols"
wrote:

On 2012-11-02, Cross-Slide wrote:
On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure. According to the Square D website the

wiring is different between delta and wye when using the buck xmfrs.

Delta only needs two xmfrs for example. So how do I determine what I

have?

Leg to leg voltages should around 240 volts.

The generated leg should make the system look like an open Delta.

But the supply being Delta or Wye will not affect the transformers.
The transformers can however be wired int Delta or Wye....

IOW, you have a supply. It can be Delta or Wye.

Then you have the Buck/Boost transformers.
They can be wired in Delta or Wye.

But Buck/Boost transformers act sort of like an autotransformer.
There is no isolation between input and output so the voltages and phase
relationships are a bit weird with delta wiring -- *unless* you use only
two transformers and operate it as "open delta", and connect the low
side of the two together, so the boosts are balanced. If you connect
the third one in as well, you'll have weird things in terms of phase
relationships. Of course, the generated phase from a rotary converter
is already a little weird, so I guess that you can live with that. :-)

Good Luck,
DoN.
Greetings DoN,
I will be using two of the three xmfrs and wiring open delta. See this
linl:
http://static.schneider-electric.us/...7414CT0201.pdf
Wiring diagram 5, page 6 is what I'll be using. Will using buck xmfrs
like this tend to equalize the voltages coming from the phase
converter?
Thanks,
Eric

wrote in message ...
On Fri, 2 Nov 2012 15:50:23 -0700, "PrecisionmachinisT"
wrote:


wrote in message ...
On Fri, 2 Nov 2012 09:34:08 -0700 (PDT), Cross-Slide
wrote:

On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure. According to the Square D website the

wiring is different between delta and wye when using the buck xmfrs.

Delta only needs two xmfrs for example. So how do I determine what I

have? I do know that leg to leg voltage is the same but that leg to

neutral for the manufactured leg is not. The two lines supplied by the

power company measure 124 volts to neutral and the manufactured leg to

neutral is 230 volts.

Thanks,

Eric

Leg to leg voltages should around 240 volts.

The generated leg should make the system look like an open Delta.

But the supply being Delta or Wye will not affect the transformers.
The transformers can however be wired int Delta or Wye....

IOW, you have a supply. It can be Delta or Wye.

Then you have the Buck/Boost transformers.
They can be wired in Delta or Wye.

Don't confuse the two things.
Well maybe I just don't understand. The Square D website has wiring
diagrams for both wye and delta SUPPLY according to my interpretation.
However, I'm pretty sure I have open delta.
Eric

http://www.contractortalk.com/attach...buck-boost.jpg


Eric it might be helpful if yiou link us to the applicable Square D conections diagram...

Also, strongly suggest that when testing any transformer connection, temporarily fuse the input side with a set of relatively low amperage fuses, say, 10 amps or so in order to protect the transformer for just in case you've made a serious mistake.
Here's the link to the Schneider Electric site:
http://static.schneider-electric.us/...7414CT0201.pdf
Square D was bought by Schneider. The diagram I think I need to use is
#5 on page 6. The xmfrs are the 1.5S46F model. I used table 15, page
19 to determine which wiring diagram to use. After looking at the
above link again I'm sure that open delta wiring is what I have and
need to use.
Eric

You are confusing open delta with your single phase neutral.

The output from your phase converter is delta.

Forget that your single phase neutral even exists; it has no bearing whatsoever here other than it's happening to at the same refrence potential as your ground proper.

That said, it does looks like your diagram should work, suggest fuse the input side like I advised earlier, wire it up and double check to make sure the output voltages are as expected before actually connecting it up to your machine.

On Sun, 4 Nov 2012 12:39:56 -0800, "PrecisionmachinisT"
wrote:


wrote in message ...
On Fri, 2 Nov 2012 15:50:23 -0700, "PrecisionmachinisT"
wrote:


wrote in message ...
On Fri, 2 Nov 2012 09:34:08 -0700 (PDT), Cross-Slide
wrote:

On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure. According to the Square D website the

wiring is different between delta and wye when using the buck xmfrs.

Delta only needs two xmfrs for example. So how do I determine what I

have? I do know that leg to leg voltage is the same but that leg to

neutral for the manufactured leg is not. The two lines supplied by the

power company measure 124 volts to neutral and the manufactured leg to

neutral is 230 volts.

Thanks,

Eric

Leg to leg voltages should around 240 volts.

The generated leg should make the system look like an open Delta.

But the supply being Delta or Wye will not affect the transformers.
The transformers can however be wired int Delta or Wye....

IOW, you have a supply. It can be Delta or Wye.

Then you have the Buck/Boost transformers.
They can be wired in Delta or Wye.

Don't confuse the two things.
Well maybe I just don't understand. The Square D website has wiring
diagrams for both wye and delta SUPPLY according to my interpretation.
However, I'm pretty sure I have open delta.
Eric

http://www.contractortalk.com/attach...buck-boost.jpg


Eric it might be helpful if yiou link us to the applicable Square D conections diagram...

Also, strongly suggest that when testing any transformer connection, temporarily fuse the input side with a set of relatively low amperage fuses, say, 10 amps or so in order to protect the transformer for just in case you've made a serious mistake.
Here's the link to the Schneider Electric site:
http://static.schneider-electric.us/...7414CT0201.pdf
Square D was bought by Schneider. The diagram I think I need to use is
#5 on page 6. The xmfrs are the 1.5S46F model. I used table 15, page
19 to determine which wiring diagram to use. After looking at the
above link again I'm sure that open delta wiring is what I have and
need to use.
Eric

You are confusing open delta with your single phase neutral.

The output from your phase converter is delta.

Forget that your single phase neutral even exists; it has no bearing whatsoever here other than it's happening to at the same refrence potential as your ground proper.

That said, it does looks like your diagram should work, suggest fuse the input side like I advised earlier, wire it up and double check to make sure the output voltages are as expected before actually connecting it up to your machine.
I will be doing as you suggest, using fuses and checking voltages.
Eric

On 2012-11-04, wrote:
On Fri, 2 Nov 2012 15:50:23 -0700, "PrecisionmachinisT"
wrote:


wrote in message ...
On Fri, 2 Nov 2012 09:34:08 -0700 (PDT), Cross-Slide
wrote:

On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure.

[ ... ]

Eric it might be helpful if yiou link us to the applicable Square D conections diagram...

Also, strongly suggest that when testing any transformer connection, temporarily fuse the input side with a set of relatively low amperage fuses, say, 10 amps or so in order to protect the transformer for just in case you've made a serious mistake.
Here's the link to the Schneider Electric site:
http://static.schneider-electric.us/...7414CT0201.pdf
Square D was bought by Schneider. The diagram I think I need to use is
#5 on page 6. The xmfrs are the 1.5S46F model. I used table 15, page
19 to determine which wiring diagram to use. After looking at the
above link again I'm sure that open delta wiring is what I have and
need to use.

O.K. Using *that* diagram, you will *get* open delta, even if you
aren't starting with it. Your rotary converter may be wired as delta or
as wye, and in most cases it should not matter.

Two things to consider:

1) The diagrams shown are to provide boost. If you want buck (to
lower the voltage) you want to interchange the joined X2 & X4
with the joined X1 and X3, all other things being the same.

2) If you want full wye, go to diagram 9 on page 7 (this requires
you to have a generated neutral from the rotary converter --
which will be hot compared to the incoming neutral, so it is
probably not a good idea.)

But -- if the transformers are big enough, you could use *one* of
them on the single phase *input* side before the rotary converter and
have the same effect -- as another poster suggested yesterday I believe.

If you need a bit more current, use two of the transformers
wired as in diagram three (also page 6) and parallel the input and
output points.

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 2012-11-04, wrote:
On 2 Nov 2012 23:00:40 GMT, "DoN. Nichols"
wrote:

On 2012-11-02, Cross-Slide wrote:
On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:

[ ... ]

But Buck/Boost transformers act sort of like an autotransformer.
There is no isolation between input and output so the voltages and phase
relationships are a bit weird with delta wiring -- *unless* you use only
two transformers and operate it as "open delta", and connect the low
side of the two together, so the boosts are balanced. If you connect
the third one in as well, you'll have weird things in terms of phase
relationships. Of course, the generated phase from a rotary converter
is already a little weird, so I guess that you can live with that. :-)


Greetings DoN,
I will be using two of the three xmfrs and wiring open delta. See this
linl:
http://static.schneider-electric.us/...7414CT0201.pdf
Wiring diagram 5, page 6 is what I'll be using.

I just posted a followup to an earlier posting of yours
containing this URL -- suggesting three ways to go, of which your
diagram 5 is one.

Will using buck xmfrs
like this tend to equalize the voltages coming from the phase
converter?

Probably not. Unless you used the wye connection and selected
to not boost one of the three phases (assuming that is is high).

But -- have you considered putting the buck-boost on the
input side to the rotary converter (thus only one buck-boost
transformer, unless you need two or three in parallel) so you reduce the
voltage to *all* of your machines to normal levels. Someone else
suggested this in an earlier followup in this thread, and I consider it
the best choice, if you have enough capacity in the buck-boost
transformers to handle the worst case load.

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"DoN. Nichols" wrote in message ...
On 2012-11-04, wrote:
On Fri, 2 Nov 2012 15:50:23 -0700, "PrecisionmachinisT"
wrote:


wrote in message ...
On Fri, 2 Nov 2012 09:34:08 -0700 (PDT), Cross-Slide
wrote:

On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure.

[ ... ]

Eric it might be helpful if yiou link us to the applicable Square D conections diagram...

Also, strongly suggest that when testing any transformer connection, temporarily fuse the input side with a set of relatively low amperage fuses, say, 10 amps or so in order to protect the transformer for just in case you've made a serious mistake.
Here's the link to the Schneider Electric site:
http://static.schneider-electric.us/...7414CT0201.pdf
Square D was bought by Schneider. The diagram I think I need to use is
#5 on page 6. The xmfrs are the 1.5S46F model. I used table 15, page
19 to determine which wiring diagram to use. After looking at the
above link again I'm sure that open delta wiring is what I have and
need to use.

O.K. Using *that* diagram, you will *get* open delta, even if you
aren't starting with it. Your rotary converter may be wired as delta or
as wye, and in most cases it should not matter.

Two things to consider:

1) The diagrams shown are to provide boost. If you want buck (to
lower the voltage) you want to interchange the joined X2 & X4
with the joined X1 and X3, all other things being the same.


Actually, you just swap input and output.


2) If you want full wye, go to diagram 9 on page 7 (this requires
you to have a generated neutral from the rotary converter --

He does not.

which will be hot compared to the incoming neutral, so it is
probably not a good idea.)

But -- if the transformers are big enough, you could use *one* of
them on the single phase *input* side before the rotary converter and
have the same effect -- as another poster suggested yesterday I believe.

If you need a bit more current, use two of the transformers
wired as in diagram three (also page 6) and parallel the input and
output points.

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 4 Nov 2012 22:17:23 GMT, "DoN. Nichols"
wrote:

On 2012-11-04, wrote:
On Fri, 2 Nov 2012 15:50:23 -0700, "PrecisionmachinisT"
wrote:


wrote in message ...
On Fri, 2 Nov 2012 09:34:08 -0700 (PDT), Cross-Slide
wrote:

On Friday, November 2, 2012 11:02:39 AM UTC-5, wrote:
Now that I'm getting some transformers to buck the voltage from my

phase converter I need to determine whether the output is wired wye or

delta. I think it's delta. but since it's a phase converter I just

don't know and need to be sure.

[ ... ]

Eric it might be helpful if yiou link us to the applicable Square D conections diagram...

Also, strongly suggest that when testing any transformer connection, temporarily fuse the input side with a set of relatively low amperage fuses, say, 10 amps or so in order to protect the transformer for just in case you've made a serious mistake.
Here's the link to the Schneider Electric site:
http://static.schneider-electric.us/...7414CT0201.pdf
Square D was bought by Schneider. The diagram I think I need to use is
#5 on page 6. The xmfrs are the 1.5S46F model. I used table 15, page
19 to determine which wiring diagram to use. After looking at the
above link again I'm sure that open delta wiring is what I have and
need to use.

O.K. Using *that* diagram, you will *get* open delta, even if you
aren't starting with it. Your rotary converter may be wired as delta or
as wye, and in most cases it should not matter.

Two things to consider:

1) The diagrams shown are to provide boost. If you want buck (to
lower the voltage) you want to interchange the joined X2 & X4
with the joined X1 and X3, all other things being the same.

2) If you want full wye, go to diagram 9 on page 7 (this requires
you to have a generated neutral from the rotary converter --
which will be hot compared to the incoming neutral, so it is
probably not a good idea.)

But -- if the transformers are big enough, you could use *one* of
them on the single phase *input* side before the rotary converter and
have the same effect -- as another poster suggested yesterday I believe.

If you need a bit more current, use two of the transformers
wired as in diagram three (also page 6) and parallel the input and
output points.

Good Luck,
DoN.
DoN,
Now I'm confused again. Looking at the diagram it lists HV and LV. So
don't I wire everything just the way the diagram is and connect my
phase converter to the HV points and the machine to the LV points?
Regarding using the xmfrs before the phase converter I need to be able
to run 45 HP. That's when all my machines are running. And I have had
all of them running at once. Not very often though. Would three of the
xmfrs in parallel do the job? Anyway, all my other machines have the
taps in them to allow running at the higher voltage. In fact, the
machine in question has taps on the control xmfr that allow the
control portion to run at the higher voltage. But the VFD does not.
Thanks,
Eric

PrecisionmachinisT wrote:

DoN. Nichols wrote:

Two things to consider:

1) The diagrams shown are to provide boost. If you want buck (to
lower the voltage) you want to interchange the joined X2 & X4
with the joined X1 and X3, all other things being the same.

Actually, you just swap input and output.


No, you reverse the polarity of the secondary winding to change
between boost & buck.

On 2012-11-04, wrote:
On 4 Nov 2012 22:17:23 GMT, "DoN. Nichols"
wrote:

On 2012-11-04, wrote:

[ ... ]

Here's the link to the Schneider Electric site:
http://static.schneider-electric.us/...7414CT0201.pdf
Square D was bought by Schneider. The diagram I think I need to use is
#5 on page 6. The xmfrs are the 1.5S46F model. I used table 15, page
19 to determine which wiring diagram to use. After looking at the
above link again I'm sure that open delta wiring is what I have and
need to use.

O.K. Using *that* diagram, you will *get* open delta, even if you
aren't starting with it. Your rotary converter may be wired as delta or
as wye, and in most cases it should not matter.

Two things to consider:

1) The diagrams shown are to provide boost. If you want buck (to
lower the voltage) you want to interchange the joined X2 & X4
with the joined X1 and X3, all other things being the same.

2) If you want full wye, go to diagram 9 on page 7 (this requires
you to have a generated neutral from the rotary converter --
which will be hot compared to the incoming neutral, so it is
probably not a good idea.)

But -- if the transformers are big enough, you could use *one* of
them on the single phase *input* side before the rotary converter and
have the same effect -- as another poster suggested yesterday I believe.

If you need a bit more current, use two of the transformers
wired as in diagram three (also page 6) and parallel the input and
output points.

Good Luck,
DoN.
DoN,
Now I'm confused again. Looking at the diagram it lists HV and LV. So
don't I wire everything just the way the diagram is and connect my
phase converter to the HV points and the machine to the LV points?

Well ... you could do that, but it would be working as an
autotransformer, not a buck-boost transformer, and the voltage
adjustment would be a bit less than you would get wired in "buck" mode.
(Exchanging the pins which I mentioned above.) Whether it would get you
close enough -- or even closer to your target voltage than the buck mode
-- remains to be seen.

If you have the full 240 V applied to the primary (two primaries
in series, based on that diagram), you will have the transformer ratio
determining the voltage out of the secondary, which will either add to
or subtract from the 240 V.

However, if you connect the 240 V to the other end of the
secondary wired in "boost" mode as shown, you will have less than 240 V
applied to the primary, so your adjustment output will be smaller. This
*might* get you closer to your desired voltage -- I just don't know. I
remember that you had the voltages you wanted and the voltage which you
really had in place of the 240 V in earlier articles, but I don't have
those available now. Same for the current and voltage ratings on the
buck-boost transformer.

Boost mode is when the voltage of the secondary adds to the
mains voltage coming in. Buck mode is when it subtracts from that
voltage coming in. Autotransformer mode is like boost mode, and what
you will get is a function of the winding ratios. (And yes, it does
reduce the voltage if you interchange the HV and LV points on the shown
wiring, just not as much as when wired in buck mode.

Regarding using the xmfrs before the phase converter I need to be able
to run 45 HP.

Ouch! That adds up to about 140 A from the single phase 240V.

That's when all my machines are running. And I have had
all of them running at once. Not very often though. Would three of the
xmfrs in parallel do the job?

Will one of them deliver about 47 A from the two paralleled
secondary windings? You've got the transformer nameplate to look at, I
don't.

Anyway, all my other machines have the
taps in them to allow running at the higher voltage. In fact, the
machine in question has taps on the control xmfr that allow the
control portion to run at the higher voltage. But the VFD does not.

A pity that the control transformer does not have a big enough
core to handle the VFD as well -- to allow tweaking the voltage to it.

So -- I guess that you use the two transformers, and see
whether they do what you need.

Good Luck,
DoN.

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