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I obtained a pole pig

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Kolas

Sat May 10 2008, 06:51PM

Registered Member #102 Joined: Thu Feb 09 2006, 08:15PM
Location: Raleigh, NC
Posts: 169

yes i experienced a large drop in power consumption when i put my resonant cap in series with my pig. though i was constantly worried about over volting it, considering the voltage rise supposedly reaches 2 * 1.141 * RMS. ~40kV

Quantum Singularity

Sat May 10 2008, 07:04PM

Registered Member #158 Joined: Sun Feb 12 2006, 09:53PM
Location: Central Ohio
Posts: 282

I'm a little late here but to ballast my pole pig I used an old arc welder I got at auction for $2. I forget exactly, think it was an old sears 275A arc welder, the case was heavily rusted, didnt have any welding cables, and the terminals for the cables were all corroded. The load control lever was also seized up. I riped of the case and gutted the thing, the only thing I needed was to un-seize the control which took me a little while with some wd-40 and a mallet. I dont have the numbers written down (it was many years ago now) but I could go from like 5A-100A control on the 240AC side. I did run a big jacobs ladder with it, about the only thing I ever did, and it would peg my 100A clamp on meter ever cycle. I'd say the arcs even though they only spanned about a foot gap were in reality 3' or more. It was just nuts. Wish I had a video. But maybe can get that thing back out this summer. Good luck and be safe.

Dr. Dark Current

Sat May 10 2008, 07:35PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Kolas wrote ...

yes i experienced a large drop in power consumption when i put my resonant cap in series with my pig. though i was constantly worried about over volting it, considering the voltage rise supposedly reaches 2 * 1.141 * RMS. ~40kV

I say don't be worried as I think the pole transformers are made to withstand a HV pulse of maybe 10x their rating (in the case of lightning strike etc.)

J. Aaron Holmes

Sun May 11 2008, 04:08AM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

Plasmaddict wrote ...

I say don't be worried as I think the pole transformers are made to withstand a HV pulse of maybe 10x their rating (in the case of lightning strike etc.)

I disagree. You definitely SHOULD worry. The big voltage you see on the pole pig's nameplate--typically 90, 100, 150, 200kV--is the Basic Impulse Level (BIL) rating. This sounds impressive, but the duration of the pulse is only expected to be a few microseconds, long enough to account for the response time of external protective devices such as surge arresters and spark gaps. If these devices don't kick in by that time, the transformer is likely to "fry". The duration of resonant overvoltage in, e.g., the scenario above, is much longer than Basic Impluse. So the BIL rating just doesn't apply. You are better off considering the actual insulation class of the transformer, which will be much lower. At the very least, the transformer should be protected by a safety gap. A good friend of mine ruined a 14.7kV 25kVA pole pig by running without a safety gap. It was a very sad thing. He'd even custom-painted the can and all. Moral: Protect your pigs. You paid big $$ for them and broke your back hauling them, so why set yourself up to do it again immediately?

Cheers,
Aaron, N7OE

Hazmatt_(The Underdog)

Sun May 11 2008, 04:46AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

I just want to mention that since you are playing with really dangerous fire now, you follow the old timer's rules about serious power: One hand holds the tool you're using, the other hand holds the plug.
The reason for this, and you WILL find out why soon, is that a residual voltage even though its only a couple of volts, gets kicked up a hundred times or so, so you can potentially have 2kv or more floating on your secondary if the plug is in the wall, a very very nasty surprise indeed. SO, put the plug in your pocket at the very least, stay supervised incase you need CPR (hope not, but it does happen!), and respect the current.

Matt

teslacoolguy

Sun May 11 2008, 01:19PM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

I can understand what you are saying and here is a couple safety precautions that i take when i am running the pig.
1. Im not even allowed to run it without my dad supervising
2. i always short out the secondary with aligator clips when im not using it.
3. i dont touch anything unless the extention cord is unplugged from the wall and from the pig.

Derek_L

Sun May 11 2008, 01:38PM

Registered Member #1125 Joined: Fri Nov 16 2007, 09:13PM
Location: Edmonton, Alberta, Canada
Posts: 62

I use a contacter with a NO pb in series with the close coil for saftey.

I let go of the remote button in my hand and the contactor opens.

----| |(pb)-----|\|(wall estop)-----|\|(door estop)-----

---------| |(on pb)------------------( )contactor-------|
|---| |(contactor seal)--|Â Â Â Â Â Â |-----O(light)---------|

I would also pound a seperate ground rod next to your garage where you will be using it.

Also if you want to go overboard (how overboard can you go on saftey) pick up a 100:5 CT off ebay, put that in your secondary side (120/240) put a low owm resistor on the ct and measure the voltage accross it.
Bring that voltage to an opamp with a set voltage (comparitor circuit) and have it trip a relay in series with your stop pb.

This is what I use, and it gives my gf a significant piece of mind when im doing my mad scientist yell in the garage.

My father didnt let me touch anything HV tell I was out of school and bought my own house :P

Have fun scaring the neighbours,

Derek L

Derek_L

Sun May 11 2008, 01:44PM

Registered Member #1125 Joined: Fri Nov 16 2007, 09:13PM
Location: Edmonton, Alberta, Canada
Posts: 62

Oh yeah and cheers to hazmat on the cpr post.
Both your dad and you should take a course.

Cheers bud,

Derek L

teslacoolguy

Sun May 11 2008, 08:57PM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

Im probably going to rig up some sort of dead man's switch for my hand connected to a contractor and about the cpr when i turn 15 in 3 days

i am signed up for a lifeguarding class and cpr is one of the things they teach

Hazmatt_(The Underdog)

Mon May 12 2008, 07:57PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Sounds good. Stay safe.

Matt

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