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#127084 - 04/18/01 01:47 AM Transformer Discussion #4 [last of this seies]
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA


T4a = 1 Phase Split Coil Transformer [split primary and secondary coils].
Note jumper location - this is the infamous "Neutral" connection point
on the
Transformer.


This Transformer core is a common 1 phase Transformer with "Split Coils" on both the Primary side and the Secondary side.
It can be used with an input voltage of either 240 VAC [Parallel Primary connection], or 480 VAC [Series Additive Primary connection].

The output can be:

A: 120 VAC 1 phase 2 wire [Parallel Secondary connection],

B: 240 VAC 1 phase 2 wire [Series Additive Secondary connection],

or

C: 120 / 240 VAC 1 phase 3 wire [Series Additive Secondary connection with a tap at the X2 - X3 jumper point of connection for the "Neutral"].


If you look at the two busses in the middle [the ones with the jumper connected], either one of those busses would be where the Common Neutral wire would be derived from.

Viewing from Left to Right, the Terminals on these busses would be:

X1 [beginning of coil "A"'s winding. Line "A" comes from here],
X2 [end of coil "A"'s winding - jumper to next coil],
X3 [beginning of coil "B" winding - jumper from other coil],
X4 [end of coil "B"'s winding. Line "B" comes from here].

This should help explain how a Neutral works with 1 phase 3 wire multiwire circuits, plus point out the major differences between how a 1 phase 3 wire's Neutral works and is derived, as compared to how a 3 phase 4 wire Wye's common works and is derived.

Any comments??

Scott SET

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#127085 - 04/18/01 05:10 PM Re: Transformer Discussion #4 [last of this seies]
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
Scott, http://www.elec-toolbox.com/usefulinfo/xfmr-3ph.htm

i wish there were some pix on the net of these strange one's you've dug up!


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#127086 - 04/18/01 07:29 PM Re: Transformer Discussion #4 [last of this seies]
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
Keep 'em comin' and keep it elementary...

I'm learnin' I'm learnin'!!!

I was a sparky for eight years before somebody explained to me how a 120/240 single phase system worked. I just couldn't grasp how you could get two voltages out of one phase! The center tap concept was all I needed.

I'm actually understanding some of this, Scott... miracles may never cease!

_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#127087 - 04/21/01 10:54 PM Re: Transformer Discussion #4 [last of this seies]
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
Virgil [Sparky66Wv],

That's what I am hoping to do with these pics, plus the related discussions that follow - to explain some of this Transformer stuff to persons whom are unsure of how they work, how to connect them and how they look.

Also, these special duty cores should be of great discussion to those whom are familair with Transformers, but have rarely seen them out of the enclosures or to have the details as these do.
Let me know if you like!!
[P.S. did the center tap explanation make sense, even easier than the thought of 120 + 120 = 240??].

Compare this jumper point to the common connection for the Wye connection in other pics, then you will see where there is a difference in a 1 phase 3 wire Neutral and a 3 phase 4 wire Wye Common.
Visual aids are so much more helpful than words!!
I'll post some schematics later.


Steve [Sparky],

When I get the website up and running, these pics and others will be posted on it.


Scott SET
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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#127088 - 04/22/01 04:26 AM Re: Transformer Discussion #4 [last of this seies]
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
Yeah, before the center tap explanation, I had racked my brain trying to figure it out.

Now I can say that the Xformer in front of my house is center tapped, 17.3 to 1 wound, 50 KVA, and is pole mounted with dielectric oil inside...

How's that!?!

Now if only we could get those linemen to understand 3-way switches...lol
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#127089 - 04/22/01 04:26 AM Re: Transformer Discussion #4 [last of this seies]
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
Scott;
they say what goes around comes around..

i put the birdfeeder out the cat window, so now both of us can see it, but not grasp it!

so if your patient enough to post some pix and expand a bit here, we'd all be appreciative and probably more interactive.

maybe i should go crack that window open a tad...


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#127090 - 04/22/01 08:04 AM Re: Transformer Discussion #4 [last of this seies]
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
Virgil,

Looks like your Primary feeder Voltage is 4160 VAC. Your information looks good!!
The Oil in the Transformer case does two things:
1: Dielectric strength to lower the possibilities of high voltage flashover to either the secondary windings, the core, or the enclosure [case - or "Pot" by some older guys]. FYI - the terminations on top where the primary feeders enter are called "Potheads" - a bunch of partying transformers ??

2: Helps conduct heat away from the windings / core and "dumps" it into the enclosure, where it can be conducted, convected or radiated away by the surrounding air.

Seen many Linemen whom could wire and understand 3 and 4 way switching circuits. There are, of course, a few that are totally clueless to the whole circuitry idea!
Seems odd, but I guess when the only complicated circuit connections would be Deltas [closed and open "Vee" and "Tee" connections], or Wyes, then it could be a brain teaser to explore outside the realm of polyphase terminations.
I still would not trade fields with them!! Too high of voltages to get shocked from, too high to fall from after getting shocked from the high voltages


Steve,

Is that a Combination "Dog Feeder, Cat Feeder, Bird Feeder"?

I would be glad to post more stuff here for discussions.
So glad everyone likes them!!!
Next pics will also include schematics, plus I'll try to figure a good way to add schematics for the 4 already posted.

Once I get the AutoCAD .DWG files converted into .GIF files [from Vector graphics to Raster graphics], I'll get together with Bill and go from there.


Scott SET
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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#127091 - 04/22/01 08:35 AM Re: Transformer Discussion #4 [last of this seies]
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
Scott;
i'd say any serious electrician would be glad to follow along! Myself, i am at a loss as to a serious reply, but i ( i'll say we for the lurkers) )are monitoring your threads with interest.

As to Virgils first thread;
I had to seek out much on my own (still trying) during my apprenticeship. Some employers simply want a grunt, won't show you or explain anything.
it should be a crime....

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#127092 - 04/22/01 05:35 PM Re: Transformer Discussion #4 [last of this seies]
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
The lineman thing was only in fun...

I would like to even be one of the guys that hangs from a chopper with a chainmail suit on with 6 ft plasma arcs coming from their wand...

I'd want the proper training of course...

And a darn good pilot.

"Conduit" dreams (lol You know, "pipe")Sorry, bad pun...

I've always been a little embarrassed with my lack of knowledge on the other side of the meter...

Not to mention that I'm way too puny to wrestle x-KCM sized steel wire in snowstorms...

4/0 Aluminum is bad enough...

Yeah, we've got a 4160/7200 Wye system here, I'm not sure what voltage is feeding them though... 16,600? I'm not sure.

I was very lucky to have been trained by Jim Hixson who, if nothing else, instilled a moral obligation to code and quality work as well as a curiosity in me. Still I'm always finding out how much I've missed from not being in a state that requires schooling for this trade. And yet I also feel I'm one of the better trained electricians in the area... Hmmm..

Please keep these threads going, Scott..
Even on days I'm not posting, I'm still reading it.
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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