I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.

i

Ignoramus17720 wrote:

I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.

i

Your custom unwinding and tap modification on the transformer voided
it's UL listing. Be sure you only ever have it powered when you are
testing something, if it were to go poof in the night and burn your
building down, your insurance would likely not pay.

"Pete C." wrote in message
.com...

Ignoramus17720 wrote:

I spent a whole day messing around with the
transformer.

The first disappointment was that even at the
lowest count of turns
tap, the transformer would put out 511 volts,
which is way too much.

After some frustrated thinking, I realized that
I could pull out the
outer winding a bit and tap into it with a
split bolt.

After a little bit of work with a calculator,
pulling the aluminum
winding a little bit, trip to McMaster Carr,
putting everything
together and applying Noalox, I ended up with a
transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts,
which is pretty good.

After a little bit of tidying up, I took a
picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a
nice 60A disconnect on
the output side, a nice "hi quality" input
cable etc.

I am SO ****ING HAPPY, like someone else would
be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3
ton coffing hoist,
which, no surprises, worked great like it is
supposed to.

i

Your custom unwinding and tap modification on
the transformer voided
it's UL listing. Be sure you only ever have it
powered when you are
testing something, if it were to go poof in the
night and burn your
building down, your insurance would likely not
pay.

Screw the insurance company.......

On 2012-01-03, Pete C. wrote:

Ignoramus17720 wrote:

I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.

i

Your custom unwinding and tap modification on the transformer voided
it's UL listing. Be sure you only ever have it powered when you are
testing something, if it were to go poof in the night and burn your
building down, your insurance would likely not pay.

I do not have any building insurance, but for sure, this is for
testing only.

i

On Tue, 03 Jan 2012 15:20:20 -0600, the renowned "Pete C."
wrote:


Ignoramus17720 wrote:

I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.

i

Your custom unwinding and tap modification on the transformer voided
it's UL listing. Be sure you only ever have it powered when you are
testing something, if it were to go poof in the night and burn your
building down, your insurance would likely not pay.

How is going to go "poof"? It's encased in a steel box.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

On 2012-01-03, Spehro Pefhany wrote:
On Tue, 03 Jan 2012 15:20:20 -0600, the renowned "Pete C."
wrote:


Ignoramus17720 wrote:

I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.

i

Your custom unwinding and tap modification on the transformer voided
it's UL listing. Be sure you only ever have it powered when you are
testing something, if it were to go poof in the night and burn your
building down, your insurance would likely not pay.

How is going to go "poof"? It's encased in a steel box.


Does a dry type transformer actually have any combustible materials?

i

Ignoramus8679 wrote:

On 2012-01-03, Spehro Pefhany wrote:
On Tue, 03 Jan 2012 15:20:20 -0600, the renowned "Pete C."
wrote:


Ignoramus17720 wrote:

I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.

i

Your custom unwinding and tap modification on the transformer voided
it's UL listing. Be sure you only ever have it powered when you are
testing something, if it were to go poof in the night and burn your
building down, your insurance would likely not pay.

How is going to go "poof"? It's encased in a steel box.


Does a dry type transformer actually have any combustible materials?

Yes, the insulation can burn, and if it starts shorting out and arcing,
hot metal bits can spray around a bit. If it's sitting in an area with
just concrete floor and walls and conduit feeding it there won't be
anything to catch on fire.

Ignoramus8679 wrote:

Does a dry type transformer actually have any combustible materials?


One caught fire in the transformer vault at my highschool one
summer. It powered the newest wing of the school, and you could still
smell it, two years later.


--
You can't have a sense of humor, if you have no sense.

Michael A. Terrell wrote:
Ignoramus8679 wrote:

Does a dry type transformer actually have any combustible materials?


One caught fire in the transformer vault at my highschool one
summer. It powered the newest wing of the school, and you could still
smell it, two years later.

Wouldn't that have been oil-filled?


--

Reply in group, but if emailing add one more
zero, and remove the last word.

Spehro Pefhany wrote:


Your custom unwinding and tap modification on the transformer voided
it's UL listing. Be sure you only ever have it powered when you are
testing something, if it were to go poof in the night and burn your
building down, your insurance would likely not pay.

How is going to go "poof"? It's encased in a steel box.


Best regards,
Spehro Pefhany

Stuff in steel boxes goes "poof" ALL the time
jk

On Mon, 09 Jan 2012 21:39:49 -0800, jk wrote:

Spehro Pefhany wrote:


Your custom unwinding and tap modification on the transformer voided
it's UL listing. Be sure you only ever have it powered when you are
testing something, if it were to go poof in the night and burn your
building down, your insurance would likely not pay.

How is going to go "poof"? It's encased in a steel box.


Best regards,
Spehro Pefhany

Stuff in steel boxes goes "poof" ALL the time
jk

Indeed it does!!!

Sometimes,...rather spectacularly


One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch

"Ignoramus17720" wrote in message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also grounded the neutral as I suggested in my other post then if one phase happens to short to the hoist frame or chain or some other piece of machinery etc and another phase shorts to the transformer enclosure or some other metal surface or piece of machinery and someone perchance comes into contact with the two of them at the same time well I'll just say there's a good likelyhood it's gonna be lights out for them unless there is also fairly HUGE grounding wire that's securely connected between between those two items.

On 2012-01-03, PrecisionmachinisT wrote:

"Ignoramus17720" wrote in message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also
grounded the neutral as I suggested in my other post then if one
phase happens to short to the hoist frame or chain or some other
piece of machinery etc and another phase shorts to the transformer
enclosure or some other metal surface or piece of machinery and
someone perchance comes into contact with the two of them at the
same time well I'll just say there's a good likelyhood it's gonna be
lights out for them unless there is also fairly HUGE grounding wire
that's securely connected between between those two items.


The 460v side is a delta and that cannot be changed. I think that I
can ground one of the legs of this delta, though? Any suggestions?

i

"Ignoramus17720" wrote in message ...
On 2012-01-03, PrecisionmachinisT wrote:

"Ignoramus17720" wrote in message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also
grounded the neutral as I suggested in my other post then if one
phase happens to short to the hoist frame or chain or some other
piece of machinery etc and another phase shorts to the transformer
enclosure or some other metal surface or piece of machinery and
someone perchance comes into contact with the two of them at the
same time well I'll just say there's a good likelyhood it's gonna be
lights out for them unless there is also fairly HUGE grounding wire
that's securely connected between between those two items.


The 460v side is a delta and that cannot be changed. I think that I
can ground one of the legs of this delta, though? Any suggestions?


No, DO NOT ground one corner.

At this point IMO you are best to just leave it as it is but I'll try and ask over on Mike Holt's forum in the next few days and get a more definitive answer for you--that's where the pros hang out when it comes to this stuff

Sorry it's just that I'm fairly busy at the moment....

"Ignoramus17720" wrote in message ...
On 2012-01-03, PrecisionmachinisT wrote:

"Ignoramus17720" wrote in message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also
grounded the neutral as I suggested in my other post then if one
phase happens to short to the hoist frame or chain or some other
piece of machinery etc and another phase shorts to the transformer
enclosure or some other metal surface or piece of machinery and
someone perchance comes into contact with the two of them at the
same time well I'll just say there's a good likelyhood it's gonna be
lights out for them unless there is also fairly HUGE grounding wire
that's securely connected between between those two items.


The 460v side is a delta and that cannot be changed. I think that I
can ground one of the legs of this delta, though? Any suggestions?



Iggy suggest go to :

http://forums.mikeholt.com/

and type "step-up transformer" into the search box....

What you'll find is that this question comes up fairly often and that the general concensus seems to be that the first choice usually is to use a wye secondary, grounding at the center connection ( which incidentally also gives you 277 vac single phase capabilities )

Second option seems to indeed involve grounding out one of the hot legs....in fact, it appears that code requires you to do so unless an additional ground fault detection system is also installed.

HTH

On 2012-01-04, PrecisionmachinisT wrote:

"Ignoramus17720" wrote in message ...
On 2012-01-03, PrecisionmachinisT wrote:

"Ignoramus17720" wrote in message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also
grounded the neutral as I suggested in my other post then if one
phase happens to short to the hoist frame or chain or some other
piece of machinery etc and another phase shorts to the transformer
enclosure or some other metal surface or piece of machinery and
someone perchance comes into contact with the two of them at the
same time well I'll just say there's a good likelyhood it's gonna be
lights out for them unless there is also fairly HUGE grounding wire
that's securely connected between between those two items.


The 460v side is a delta and that cannot be changed. I think that I
can ground one of the legs of this delta, though? Any suggestions?



Iggy suggest go to :

http://forums.mikeholt.com/

and type "step-up transformer" into the search box....

What you'll find is that this question comes up fairly often and
that the general concensus seems to be that the first choice usually
is to use a wye secondary, grounding at the center connection (
which incidentally also gives you 277 vac single phase capabilities
)

Second option seems to indeed involve grounding out one of the hot
legs....in fact, it appears that code requires you to do so unless
an additional ground fault detection system is also installed.

PM, I cannot use a wye secondary, as my secondary (high side) is delta
connected.

i

On 2012-01-04, Ignoramus8679 wrote:
On 2012-01-04, PrecisionmachinisT wrote:

"Ignoramus17720" wrote in message ...
On 2012-01-03, PrecisionmachinisT wrote:

"Ignoramus17720" wrote in message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also
grounded the neutral as I suggested in my other post then if one
phase happens to short to the hoist frame or chain or some other
piece of machinery etc and another phase shorts to the transformer
enclosure or some other metal surface or piece of machinery and
someone perchance comes into contact with the two of them at the
same time well I'll just say there's a good likelyhood it's gonna be
lights out for them unless there is also fairly HUGE grounding wire
that's securely connected between between those two items.


The 460v side is a delta and that cannot be changed. I think that I
can ground one of the legs of this delta, though? Any suggestions?



Iggy suggest go to :

http://forums.mikeholt.com/

and type "step-up transformer" into the search box....

What you'll find is that this question comes up fairly often and
that the general concensus seems to be that the first choice usually
is to use a wye secondary, grounding at the center connection (
which incidentally also gives you 277 vac single phase capabilities
)

Second option seems to indeed involve grounding out one of the hot
legs....in fact, it appears that code requires you to do so unless
an additional ground fault detection system is also installed.

PM, I cannot use a wye secondary, as my secondary (high side) is delta
connected.

i

I asked a question on mikeholt, I will see if I am approved yb the
moderator.

i

PrecisionmachinisT wrote:

id wrote in
message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of
turns tap, the transformer would put out 511 volts, which is way
too much.

After some frustrated thinking, I realized that I could pull out
the outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty
good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink



I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes
Benz car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also
grounded the neutral as I suggested in my other post then if one
phase happens to short to the hoist frame or chain or some other
piece of machinery etc and another phase shorts to the transformer
enclosure or some other metal surface or piece of machinery and
someone perchance comes into contact with the two of them at the
same time well I'll just say there's a good likelyhood it's gonna be
lights out for them unless there is also fairly HUGE grounding wire
that's securely connected between between those two items.

Why would you need a *huge* ground wire. All
you need is one big enough to hold together
long enough to trip the breaker. I don't have
the charts in front of me, but that's usually
a conductor appreciably smaller than the phase
conductors.

On 2012-01-03, Jim Stewart wrote:
PrecisionmachinisT wrote:

id wrote in
message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of
turns tap, the transformer would put out 511 volts, which is way
too much.

After some frustrated thinking, I realized that I could pull out
the outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty
good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink



I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes
Benz car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also
grounded the neutral as I suggested in my other post then if one
phase happens to short to the hoist frame or chain or some other
piece of machinery etc and another phase shorts to the transformer
enclosure or some other metal surface or piece of machinery and
someone perchance comes into contact with the two of them at the
same time well I'll just say there's a good likelyhood it's gonna be
lights out for them unless there is also fairly HUGE grounding wire
that's securely connected between between those two items.

Why would you need a *huge* ground wire. All
you need is one big enough to hold together
long enough to trip the breaker. I don't have
the charts in front of me, but that's usually
a conductor appreciably smaller than the phase
conductors.

I used grounding wire of the same size.

i

"Jim Stewart" wrote in message ...
PrecisionmachinisT wrote:

id wrote in
message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of
turns tap, the transformer would put out 511 volts, which is way
too much.

After some frustrated thinking, I realized that I could pull out
the outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty
good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink



I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes
Benz car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also
grounded the neutral as I suggested in my other post then if one
phase happens to short to the hoist frame or chain or some other
piece of machinery etc and another phase shorts to the transformer
enclosure or some other metal surface or piece of machinery and
someone perchance comes into contact with the two of them at the
same time well I'll just say there's a good likelyhood it's gonna be
lights out for them unless there is also fairly HUGE grounding wire
that's securely connected between between those two items.

Why would you need a *huge* ground wire. All
you need is one big enough to hold together
long enough to trip the breaker. I don't have
the charts in front of me, but that's usually
a conductor appreciably smaller than the phase
conductors.

Impedance issues, if I recall correctly....basically, there does not necessarily have to be a "dead short" in order for there to still be a significant personnell hazard with this scenario....feel free to research some more on your own if you disagree.

--I grounded mine at the center connection, having investigated this all fairly thorougly nearly two decades ago and so I don't really don't feel the need to go there all over again myself...

In any case, grounding the center connection of said wye configugation also insures that in no instance will a fault potential ever develop that is greater than 277 volts unless ground continuity is lost on two or more individual more branch circuits.

FWIW...good arc flash at 480 can basically vaporize about 1/2 of your hand pretty much instantaniously.

On 2012-01-04, PrecisionmachinisT wrote:

"Jim Stewart" wrote in message ...
PrecisionmachinisT wrote:

id wrote in
message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of
turns tap, the transformer would put out 511 volts, which is way
too much.

After some frustrated thinking, I realized that I could pull out
the outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty
good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink



I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes
Benz car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also
grounded the neutral as I suggested in my other post then if one
phase happens to short to the hoist frame or chain or some other
piece of machinery etc and another phase shorts to the transformer
enclosure or some other metal surface or piece of machinery and
someone perchance comes into contact with the two of them at the
same time well I'll just say there's a good likelyhood it's gonna be
lights out for them unless there is also fairly HUGE grounding wire
that's securely connected between between those two items.

Why would you need a *huge* ground wire. All
you need is one big enough to hold together
long enough to trip the breaker. I don't have
the charts in front of me, but that's usually
a conductor appreciably smaller than the phase
conductors.

Impedance issues, if I recall correctly....basically, there does not
necessarily have to be a "dead short" in order for there to still be
a significant personnell hazard with this scenario....feel free to
research some more on your own if you disagree.

--I grounded mine at the center connection, having investigated this
all fairly thorougly nearly two decades ago and so I don't really
don't feel the need to go there all over again myself...

In any case, grounding the center connection of said wye
configugation also insures that in no instance will a fault
potential ever develop that is greater than 277 volts unless ground
continuity is lost on two or more individual more branch circuits.

FWIW...good arc flash at 480 can basically vaporize about 1/2 of
your hand pretty much instantaniously.

I thought that 45 kVA would not be enough to create a large arc
flash?

i

Ignoramus8679 wrote:

On 2012-01-04, PrecisionmachinisT wrote:

"Jim Stewart" wrote in message
...
PrecisionmachinisT wrote:

id wrote in
message ...
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of
turns tap, the transformer would put out 511 volts, which is way
too much.

After some frustrated thinking, I realized that I could pull out
the outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty
good.

After a little bit of tidying up, I took a picture.


https://picasaweb.google.com/lh/phot...eat=directlink



I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes
Benz car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.


Great.

But just so you know....

--unless you connected the output into a wye configuration and also
grounded the neutral as I suggested in my other post then if one
phase happens to short to the hoist frame or chain or some other
piece of machinery etc and another phase shorts to the transformer
enclosure or some other metal surface or piece of machinery and
someone perchance comes into contact with the two of them at the
same time well I'll just say there's a good likelyhood it's gonna be
lights out for them unless there is also fairly HUGE grounding wire
that's securely connected between between those two items.

Why would you need a *huge* ground wire. All
you need is one big enough to hold together
long enough to trip the breaker. I don't have
the charts in front of me, but that's usually
a conductor appreciably smaller than the phase
conductors.

Impedance issues, if I recall correctly....basically, there does not
necessarily have to be a "dead short" in order for there to still be
a significant personnell hazard with this scenario....feel free to
research some more on your own if you disagree.

--I grounded mine at the center connection, having investigated this
all fairly thorougly nearly two decades ago and so I don't really
don't feel the need to go there all over again myself...

In any case, grounding the center connection of said wye
configugation also insures that in no instance will a fault
potential ever develop that is greater than 277 volts unless ground
continuity is lost on two or more individual more branch circuits.

FWIW...good arc flash at 480 can basically vaporize about 1/2 of
your hand pretty much instantaniously.

I thought that 45 kVA would not be enough to create a large arc
flash?

i
The problem is that during fault conditions, these transformers are
capable of producing MUCH more than 45 KVA, possible ten times that
for a couple cycles, maybe more, depending on the primary feed.
That is getting into the truly dangerous region, where anyone in
the same room and not wearing flash-protective suits could be
permanently injured.

I don't think corner grounding is such a great idea. You can make
a neutral transformer from any transformer that has 3 windings
on a single core, and is rated for 480 per winding. Just tie
all 3 of the same end of the windings together, and that is your neutral.

All modern delta-secondary transformers generally have one of these, it
looks like a modest control transformer. They usually have it set
up with a ground-fault circuit, so it serves two purposes.

Jon

"Ignoramus8679" wrote in message
...

I thought that 45 kVA would not be enough to create a large arc
flash?

i

Be very carefull.

http://www.youtube.com/watch?v=-iClXrd50Z8

http://www.youtube.com/watch?v=pCZax3vIslo

Best Regards
Tom.
--
http://fija.org/

On 1/3/2012 1:06 PM, Ignoramus17720 wrote:
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.

i
Why would someone want a MB? At least a new one. Our car is a 1983 MB
300SD with 222,000 miles. We were going to trade it in on a VW
Sportwagen, diesel, but since the MB has no value we decided to just
keep driving it till it won't.

Aluminum windings? Must be fairly new xformer.

Paul

On 2012-01-03, Paul Drahn wrote:
On 1/3/2012 1:06 PM, Ignoramus17720 wrote:
I spent a whole day messing around with the transformer.

The first disappointment was that even at the lowest count of turns
tap, the transformer would put out 511 volts, which is way too much.

After some frustrated thinking, I realized that I could pull out the
outer winding a bit and tap into it with a split bolt.

After a little bit of work with a calculator, pulling the aluminum
winding a little bit, trip to McMaster Carr, putting everything
together and applying Noalox, I ended up with a transformer with a
more suitable turns ratio on the secondary.

The output from the transformer is 476 volts, which is pretty good.

After a little bit of tidying up, I took a picture.

https://picasaweb.google.com/lh/phot...eat=directlink

I now have a nice 45 kVA transformer, with a nice 60A disconnect on
the output side, a nice "hi quality" input cable etc.

I am SO ****ING HAPPY, like someone else would be with a Mercedes Benz
car.

I immediately went on and tested the 460 volt 3 ton coffing hoist,
which, no surprises, worked great like it is supposed to.

i
Why would someone want a MB? At least a new one. Our car is a 1983 MB
300SD with 222,000 miles. We were going to trade it in on a VW
Sportwagen, diesel, but since the MB has no value we decided to just
keep driving it till it won't.

Aluminum windings? Must be fairly new xformer.

Paul

I bought it for 50 bucks at auction. It will pay for itself in
many multiples.

i