Setting Up a Pole Pig's Wiring
a Tesla List discussion
Updated: 07-29-06
Date: Sun, 30 Apr 2006 16:17:15
-0600 - Subject: Setting up a pole pig's
wiring - Original poster: "D.C. Cox"
Just connect the center two connections together and float them, i.e., don't
ground them on the 240 VAC side. Apply hot 1 (H1) and hot 2 (H2) across the
outer two LV bushings. Ground one side of the sec HV bushing (X1) and the
output is off the other non-grounded bushing (X2). The pig's case is grounded
and this point is also hooked directly to one of the bushings (X1).
This produces less stress on the HF sec coil as the interior side of the primary
is at X1 (grounded) potential. Less chance of corona formation in this area as
both the interior of the pri and bottom of the HF sec coil are both at ground
potential.
Dr. Resonance
>For the same reason that you don't tie the center
LV bushing of
a pole pig to ground when using it as a Tesla
power transformer.
David
Date: Sun,
30 Apr 2006 19:29:57 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: FIFTYGUY
>This produces less stress on the HF sec coil as
the interior side of
the primary is at X1 (grounded) potential.
Doesn't this assume that X1 is always the connection closest to the primary
winding, or is this the convention with pole pigs? Otherwise it could make the
situation worse?
-Phil LaBudde
Date: Mon,
01 May 2006 10:25:26 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "Barton B.
Anderson"
Yes, but there is no assumption. D.C. said "as the interior side of primary is
at X1 (grounded) potential". That indicates, connecting X1 to ground. That is
clear. I would however clarify ground as RF ground. I've been running this
connection on my pig ever since David discussed with me a few years ago.
This is not something that can be done with an NST system where the hv winding
is center-tap grounded. But, with a depotted NST, the center-tap to ground
connection can then be removed and run the same
way to minimize pri to sec stress.
Take care,
Bart
Date: Mon,
01 May 2006 16:46:31 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: FIFTYGUY
In a message dated 5/1/06 12:37:55 PM Eastern Daylight Time,
>Yes, but there is no assumption. D.C. said "as
the interior side of
>primary is at X1 (grounded) potential". That
indicates, connecting X1
>to ground. That is clear.
Sorry, I'm a little slow, but that still doesn't clarify it to me. If anything,
this raises the additional issue of which end of the *primary* winding is
adjacent to the core or secondary winding. Again, unless I'm missing some
conventional labeling of pole pigs, the worst case could end up:
One end of primary (LV winding), the end furthest from core, at ground potential
Other end of primary (LV winding), the end closest to core or to the secondary's
(HV winding) HV end, at 240V One end of secondary (HV winding), the end furthest
from core, at ground potential Other end of secondary (HV winding), the end
closest to the core or to the primary's (LV winding) 240V end, at 15kV
Obviously this is the highest-stress situation, and best-case is the complete
opposite. My concern is calling the "H1" or "X1" labeled ends of the windings
the ones closest to the core or other winding. Is there some convention that pig
manufactures must follow when labeling, or should a pig owner open and verify
the connections?
>I would however clarify ground as RF ground.
Thank you for that clarification.
>This is not something that can be done with an
NST system where the
>hv winding is center-tap grounded. But, with a
depotted NST, the
>center-tap to ground connection can then be
removed and run the same
>way to minimize pri to sec stress.
On an (9, 12, or 15kV) NST, the interior ends of both HV windings are both
grounded to the core. Grounding one "bushing end" puts 4.5, 6, or 7.5kV stress
at the center of the HV windings to core, where there was zero stress before. If
the depotted NST HV winding fails, and the core isn't still grounded, that puts
the core floating at 4.5 - 7.5kV where it normally would be at ground. And thus
it would put an abnormal stress to the primary winding adjacent to the core. So
in that respect I don't think that connection scheme minimizes primary to
secondary stress.
- Phil LaBudde
Date: Mon,
01 May 2006 19:54:37 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "Barton B.
Anderson"
Hi Phil,
Neither end of the LV windings are at ground. They are floating. 240 Vac would
be typical in the US connecting the LV across X1 and X3. X2 is left
unconnected. I see we got our X's and H's mixed up. Thanks for being
persistent.
>One end of secondary (HV winding), the end
furthest from core, at ground potential
Other end of secondary (HV winding), the end
closest to the core or to the primary's (LV winding) 240V end, at 15kV
Ideally, the core side should be at RF ground as this is the least stressful
situation. I connect H2 on my pig to RF ground..
>Obviously this is the highest-stress situation,
and best-case is the complete opposite. My concern is calling the "H1"
or "X1" labeled ends of the windings the ones closest to the core
or other winding. Is there some convention that pig manufactures
must follow when labeling, or should a pig owner open and verify
the connections?
Not a bad idea. Popping the lid and taking a look doesn't hurt. But there is a
standard for all distribution transformers. Looking at the transformer so that
the LV bushings are facing you, the HV bushing H1
is on the left and H2 is on the right. The LV bushing X1 is on the right. X2
(neutral) is in the center and X3 is on the left. That is the standard for a
single phase distribution transformers.
The transformer core is connected to the case. I have left the core as built and
tie RF ground to the transformer case. Mains ground stops at the control panel.
In other words, I make sure RF ground and mains ground are not connected
(otherwise, you're going to get little shocks here and there at the control
cabinet).
You're concern is certainly valid because we got our X's and H's mixed up. H2
should be at RF ground. This is the HV side closest to the core and when looking
at the LV bushings, H2 is the HV bushing on the right.
> On an (9, 12, or 15kV) NST, the interior
ends of both HV windings are both grounded to the core.
Grounding one "bushing end" puts 4.5, 6, or 7.5kV stress at the center of
the HV windings to core, where there was zero stress before. If the depotted NST HV winding fails, and the core isn't still
grounded, that puts the core floating at 4.5 - 7.5kV where it normally
would be at ground. And thus it would put an abnormal stress to the
primary winding adjacent to the core. So in that respect I don't
think that connection scheme minimizes primary to secondary
stress.
Yes, the center of the HV side is at the core. I'm talking about "if" the NST is
unpotted, that situation could be removed. Then it could be setup just like a
distribution transformer. But I don't unpot NST's (too messy). Just a
possibility if someone wanted to go that route. The case of the NST would also
be tied to RF ground. I set my
NST under the coil and tie RF ground to the case. Mains ground is nowhere near
and only back at the control.
Hope that helps clarify.
Take care, Bart
Date: Mon,
01 May 2006 22:28:18 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "D.C. Cox"
Sorry for the confusion. I was referring to the pri coil of the Tesla xmfr and
not the pri coil of the pole xmfr.
Pole xmfrs typically used X1 and X2 for the 220 volt side and designate H1 and
H2 on the 14.4 kV side.
We always ground one of the HV bushings (either H1 or H2) to the main 220 volt
ground. This then goes from the power supply over to the coil via standard 10
AWG THHN wire and when connecting to the spark
gap, it also connects to the inside of the pri Tesla transformer copper tubing
and also to the main RF ground. The base of Tesla coil sec also connects to the
main RF ground. We then run a 2 ought fine stranded welding cable to our main
bldg ref ground which is connected to 2 parallel external copper grounds
outside. In our museum applications we always have them install a 2 ought
welding cable from dual exterior bldg ground directly to the demo stage area
where it terminates as the base of the Tesla sec coil, ie, main RF ground.
Dr. Resonance
-
Sent: Monday, May 01, 2006 6:54 PM
Subject: Re: Setting up a pole pig's wiring
Date: Mon,
01 May 2006 22:28:38 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "Gerry Reynolds"
Hi Bart,
When you say H2 is the side closest to the core, are you saying the inner winding
of the H2 coil goes to the bushing. Could you describe the HV winding
geometry?? one coil or two??? and how the inner/outer windings are
connected??? My nameplate suggest two HV coils, but if this is the case, it
would make no sense to me why the inner winding of one of the coils would be
brought out to the HV bushing. Everything you have said would make perfect
sense if there was only one HV coil.
Gerry R.
Date: Mon,
01 May 2006 20:49:09 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "Gerry Reynolds"
Hi Phil,
This X1... does seem a little confusing. I looked at my PIG (2 ears) and the
two HV outputs are labeled H1 and H2 on its nameplate. I presume they connect to
the outer windings on their respective coils. The two HV coils have a common
internal node (the center tap) that is not connected to the core. If one HV
bushing is grounded,
this common node will (presumably the inner winding of each coil) will be at
7200V. If neither HV bushing is grounded, the output will be differential like
a two bushing NST. Dont know what the common node will float to, but I'm
guessing zero volts if everything is balanced.
The LV side of my pig nameplate shows two coils, where each coil is internally
wired in parallel for 120V operation or internally wired in series for 240V
operation. All LV nodes are labled as X; not X0, X1, nor X2. My pig is wired
for 240V operation where the two outer LV bushings are powered and the middle
bushing is left alone. The middle bushing is, however, connected to the common
node (center tap for 240 operation) between the two LV windings internally. The
voltage driven onto each of the outer LV bushings are normally +120Vac and
-120Vac (both hot and 180 degrees out of phase with each other). This is how
240V is delivered in the USA. Even the output of a 240V variac has both output
terminals hot. In this case, one output terminal connected to the wiper sweeps
from the -120Vac side to the +120Vac side to give you a 0 to 240Vac output
differential. The other output terminal is common with one of the input
terminals. You can NOT ground one of the LV bushings and drive 240Vac to the
other unless that is what your power source is providing. I also believe the
common opinion is to not ground the center LV bushing when driving the outer two
bushings with +120Vac and -120Vac since the two LV coils may not be balanced.
The confusion, I believe, is mostly on the HV side and whether to
ground or not ground one of the HV bushings. If someone could explain the
rational for grounding one of the HV bushings using terminology such as the
"inner winding of H1" and "outer winding of H1", and "inner winding of H2" and
"outer winding of H2", this would help. The case of the pig (core is connected
to case internally) also needs to be grounded to either mains ground or RF
ground and there will be different and legitimate opinions as to which one.
Gerry R
Date: Tue,
02 May 2006 10:29:06 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: Yurtle
Turtle <yurtle_t
Sounds like there isn't any consistency with pig LV designation. Dr. R's use X1
and X2, mine uses X1 and
X3, with X2 being neutral, and Gerry stated his were all simply X.
Adam
Date: Tue,
02 May 2006 10:29:19 -0600 - Subject:
Re: Setting up a pole pig's wiring - Original poster: Yurtle
Turtle
Mine has two LV coils but only one HV coil:
http://www.hot-streamer.com/adam/garage/pig_14.4kV_25kVA_3.jpg
Does yours have a diagram showing this, or simply a description? Mine does 14.4
and 7.2 kV so two diagrams
for the LV side.
Adam
Date: Tue,
02 May 2006 18:01:50 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original
poster: Don Murray
Adam
This transformer can be used in 4 different primary distribution systems, 7200V
phase to phase & 12470V phase to ground both on switch position 1 on switch
position 2 14400V phase to phase & 24940V phase to
ground. Even though the diagram does not show two primary coils the name plate does
show SW POS 1 7200 and SW POS 2 14400.
On the side of the can there will be a switch could look like a pointer 4" long
pointed on one end and a screw in the middle you have to back out to rotate the
pointer 90 deg the other type will look like a knob about 3" across with a hole
in the middle unscrew this knob turn it over and the hole in the middle will fit
a switch under the knob.
>Does yours have a diagram showing this, or simply
a description? Mine does 14.4 and 7.2 kV so two
diagrams
for the LV side.
Two diagrams for the LV side show series and parallel you have to remove the
lid to make this change.
This is a subtractive polarity transformer X 1,2,3 left to right additive
polarity would be X 3,2,1 left to right. To test for Polarity jumper H1 to the
left X bushing put 240V across H1 and H2 now read volts across H2 and right X
bushing if you get 264V it is additive if you get 216V it is subtractive. -
Don
I fixed a typo
Date: Tue,
02 May 2006 20:40:40 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "David Rieben"
Hi Don,
Isn't the lower voltage ratings - 7200 and 14400- the "phase-to-ground" rating
and the higher voltage ratings - 12470 and 24940- the "phase-to-phase" rating?
David Rieben
Date: Tue,
02 May 2006 20:40:50 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "Barton B.
Anderson"
Hi Gerry,
H1 is connected to a bushing and one outer hv winding. H2 is connected to a
bushing. The wire from the bushing is the common to the tap. The tap wiring (1
through 5) run down between the LV and HV windings
attaching near the bottom of the winding. There is no hv center connection to
the core. It's a single winding
which is wound around the LV winding. H1 appears to be nearest the inside of the
coil, so the H2 would end up towards the outer side nearest the outer core.
That's why I referenced H2 to RF ground. However, I doubt it makes any
difference which hv bushing runs to the core, otherwise, we probably would have
had issues in the past by now.
Two HV coils would make no sense (electrically) for single phase buck-boost
transformer (a few hundred volts). My diagram on the pig for the hv side shows a
single coil with the tap diagram in the center, however, that doesn't indicate
two coils. The taps must be on one end of the winding for the typical few
hundred volt taps.
Take care, Bart
Date: Tue,
02 May 2006 20:40:59 -0600 - Subject:
Re: Setting up a pole pig's wiring - Original
poster: "Barton B. Anderson"
Hi Adam,
Regardless of what the name plate states, there is a standard. Your particular
transformer is labeled "correctly".
X1-X2-X3 with X2 being neutral. This is the standard for Additive Polarity of
which distribution pole transformers are wired. If the pole transformer was 3
phase, you would have 3 hv terminals. In that case, H3-H2-H1 with H1 on the left
looking from the LV bushing side.
The standard relates to the direction of induced voltage, from HV winding to LV
winding. The standard is necessary to properly parallel 3-phase and 1-phase
transformers as well as connecting to existing
equipment, not to mention setting up potential and current transformers for
monitoring.
A potential transformer is different. It is Subtractive Polarity. Looking from
the LV side, H1 is on the left and H2 is on the right. Looking from the LV
side, X1 is on the left and X2 is on the right.
Note, the X numbering is opposite hand to what was mentioned earlier with the
distribution transformer (X1 on the right, etc..).
BTW, the term "polarity" refers to how the leads are brought out of the
transformer. Induce H1 to H2, and X1 to X2 would have the same polarity (same
phase). That is essentially why there is a standard.
Take care, Bart
Mine has only one diagram. Your LV windings is certainly two for the series (14400) or parallel (7200) operation. Your hv winding is still a single winding. According to your spec plate, you have no tap on the case.
Take care, Bart
Date: Wed,
03 May 2006 07:11:39 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "Barton B.
Anderson"
Hi Don,
Good observation. The spec plate "should" represent phase. It may or may not
represent how the terminals are configured. I see subtractive polarity is
plainly labeled on the plate. Interesting, I thought all "distribution"
transformers should be additive polarity, but apparently, that isn't so.
Thanks for pointing that out.
Take care, Bart
Date: Wed,
03 May 2006 07:11:50 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original
poster: Don Murray
Tesla list wrote:
>Original poster: "David Rieben"
>Hi Don,
>Isn't the lower voltage ratings - 7200 and 14400-
the "phase-to-ground" rating
>and the higher voltage ratings - 12470 and 24940-
the "phase-to-phase" rating?
>David Rieben
Hi David
Those voltages are all phase to phase system voltages. On 12470 the phase to
ground would be 7200, and on 24940 phase to ground would be 14400.
The left diagram on the name plate shows the secondary in series; A to X1, C&B
to X2, and D to X3. The right diagram shows the secondary in parallel; A&C to X1
and B&D to X2. Low voltage is 120/240.
Don
Date: Wed,
03 May 2006 07:11:59 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original
poster: "Gerry Reynolds"
Hi Adam,
Its a diagram that is kinda funky. It shows something weird at the center coil
position and the two HV coils dont directly connect on the diagram. I've
determined hey are connected to each other in reality and not connected to core
by ohming it out.
Gerry R.
Date: Wed,
03 May 2006 07:12:10 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "Gerry Reynolds"
Hi Bart,
I'm still a little confused on your meaning of "tap wiring". To me, tap means an
intermediate connection to a coil and implies there are two other possible
connections on both sides of the coil. If this is how you are using the term,
then H1 connects to one side of the HV coil and H2 connects to an intermediate
point on the coil and then
I'm wondering what the other end of the coil is connected to. I suspect you are
using "tap" to mean a connection to the inner winding of the HV coil (H2) and H1
connects to the outer winding of that coil.
I think from what you say, there is only one HV coil that is wound on top of the
LV windings. There must be insulation between the LV and HV coils that must
standoff a significant voltage, but the breakdown
from H2 to LV must be lower than from H1 to LV or core. Is this interpretation
correct???
Have people ever had problems not grounding H2, but instead leaving the HV
outputs floating???
Gerry R.
Date: Wed,
03 May 2006 15:53:01 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: Yurtle
Turtle
There is only one primary (HV) coil and two secondary (LV) coils. Perhaps the
confusion is that we run them
backwards, so the pig's primary is our secondary.
If it helps, the two secondary coils may be connected either in parallel or in
series, by moving a switch on
the side of the pig, for use on either 7,200 or 14,400 volts. The only
connection to the core is an optional
grounding strap, that connects the neutral bushing to the case. I don't use
that. The primary isn't
connected to anything. I run it with one bushing grounded.
Adam
Hi Gerry,
The tap is a 5 position switch located on the side of the case near the top. It switches the HV side. The switch has 1 common and then switches between 5 positions which are taps at the HV winding. Here are the tap voltages:
5 = 12540
4 = 12870
3 = 13200
2 = 13800
1 = 14400
Thus, the LV output (in normal distribution use) can be adjusted as necessary. I of course keep the transformer tapped at position 1. This switch is just below the top of the oil. Note the voltages and where the VH winding must be tapped to attain those voltages.
H1 is at one end of the HV winding. H2 runs to the tap switch common. The tap positions run down to the coil and I suspect are on the outer winding, but I would have to disassemble to be positive (which I'm not going to do).
Yes, there are layers of insulation paper between the HV and LV coils. This is a beefy little 10KVA unit at 1.8% impedance.
The breakdown voltage would be to full scale on the opposite end of the non-grounded HV terminal. I've ran the pig floating for a long time and also with H2 grounded (for a long time). No problems ever in either mode of operation. The standoff voltage is more than enough. The oil is non-pcb and crystal clear.
Take care, - Bart
Date: Wed,
03 May 2006 19:40:55 -0600 - Subject:
Re: Setting up a pole pig's wiring - Original
poster: "Barton B. Anderson"
Here's a little document that may help. I pulled it off the internet and put it
up in a temporary directory.
http://www.classictesla.com/temp/TransfPol.pdf
Take care, Bart
Date: Wed,
03 May 2006 23:41:18 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "Gerry Reynolds"
Hi Bart,
OK, I think I understand now. My pig doesn't have this tap switch unless it is
on the inside. Also no mention of it on the diagram. You say that you suspect
the tap connections are on the outer HV winding??? If this is true, then why
ground H2.? I thought the previous discussion was saying that H2 (via the tap
switch) goes to the inner windings of the HV coil that is directly on top of the
LV winding and this is why it is best to ground H2.
Gerry R.
Date: Thu,
04 May 2006 20:25:28 -0600 - Subject:
Re: Setting up a pole pig's wiring -
Original poster: "Barton B.
Anderson"
Hi Gerry,
The point was that it might be a good idea to ground the coil side nearest the
core. The nearest core to the hv coil is not the core center, but the outer
portion of the E core. Thus, at least in this case, H2. I think there would have
been problems long ago as I doubt anyone has payed much attention to what's
what.
Take care, Bar
Date: Fri, 05 May 2006 09:25:34
-0600 - Subject: Re: Setting up a pole
pig's wiring - Original poster: "Gerry Reynolds"
Hi Bart,
This makes sense if H2 to core breakdown is lower voltage than H1 to LV winding
(assuming H2 is outer winding and H1 is inner winding). I guess I'm more
concerned about arcing to the LV winding because of subsequent consequences.
Gerry R.
Continued on the www.pupman.com archive for May 2006
- 5-22-11