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nice and clean Jacob's Ladder

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radiotech

Fri Jan 29 2010, 10:15PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
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Posts: 1546

The other thing about NSTs being rarely involved is even if the tubes of signs are within reach, if someone fell against it the tube would break, and the specs for signs bury the connections well below the front in bushings. However, taken out of their element, and used as an appliance, the game changes. The approval on those things is approval to use in an approved device only.

Here's a cute scan :Hawkins, M New Catechism of Electricity Theo Audel & Co. New York (1896).

The rat part amuses me. A rat blew the door off a Korndorfer
control in my area one night. We thought it was just a trip, but the generation dept said it was our problem. The rat, was there, eyes intact on the terminals. 6600 volt system.

dmg

Fri Jan 29 2010, 11:41PM

Registered Member #2628 Joined: Fri Jan 15 2010, 12:23AM
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Posts: 627

sucks to be you if you had to clean that rat (whats left of it) its eyes were probably permanently fused to the terminals...

and I trust that If you can build a jacobs ladder out of a few mots and get it working nicely, I would also assume you are not a complete retard and you wont stick your hand in the arc.

still, I dont think that MOTs are the worst, shock wise, out of all the things I do, I consider my 60hz (or 50 if you dont live in canada) 120 mains the deadliest, while a mot can provide around 2A shorted, If you dont have a ground fault interrupter and a faulty breaker, mains can reach 100A shorted, even if only less then a second before the breaker kicks, It is still enough to do long term damage, cause disabilities, brain damage and most likely cause cardiac fibrillation, unless you have someone around to help you, you are pretty much screwed.

and as radiotech said, If you work in a place that handles high voltage at high amperage, the danger is obviously far greater then just mains. (you will look like that rat.)

Arcstarter

Sat Jan 30 2010, 01:17AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

I don't know about that, i can comfortably touch mains, if i do not hold the electrodes too hard. If i hold them hard, there is no way i could continue to hold them, and i would have to let go. I am way more scared of a ZVS driver with an LOPT than i am of mains. And rightly so, i'd think. MOT's will limit themselves to about 20 amps, but at that point you might as well say you are pretty screwed. You can live through a MOT shockin' ya, even without any damage. But it is incredibly dangerous. Chances are, you'd die.

rp181

Sat Jan 30 2010, 04:06AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
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Posts: 1529

Comfortably touch mains? That sounds like you do it for fun :)
I was walking around in a house under construction, and being me, was picking things up, and just kind of looking around. Turns out the builders left the power on, and my hand brushed the metal plates in a central fuse box. That was the worst shock I had ever had, I could feel the locking (took me a little to get of). The upper part of my body was tense for a couple of hours.
Im pretty sure this was a 220v shock, as I have gotten shocked when plugging in poorly designed adapters into poorly designed surge protectors, and it was not bad at all.

radiotech

Sat Jan 30 2010, 04:09AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
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Posts: 1546

What happens is this : You get very good at what you do, having been shocked by NST or MOT, develop a lot of confidence. But sooner or later (or maybe even never) you come across a situation that needs action; Your skillset then is your enemy, if the energy level is much higher.

What you want to do now with any of the experiments, is practice some safe electrics. Start with the one-hand-rule. One hand behind your back doing anything on energized equipment.

What would you do if you were working on this stuff.
exiter motor-generator. 6600 volt motor/alternators with decoupled
steam turbines, View of 1500 Amp/600 Volt DC breaker, and the Korndorfer, in better days. Rat blew out center section

dmg

Sat Jan 30 2010, 05:32AM

Registered Member #2628 Joined: Fri Jan 15 2010, 12:23AM
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Posts: 627

I do keep in mind the one hand rule, thats why I am still writing on this forum...
I did experience a mains shock a while ago, and had a near miss one time with both hands,
the mains shock resulted in a fault and a core of a small motor (microwave fan) was energized at 120V and I was conviniantly standing on grass. so that was a very painfull shock,

however electricity doesn't always behave as you would expect:
on one of my mot projects, I was testing it, and afterwards I desided to put a 5 microfarad PFC capacitor in parralel with the incoming mains, point is, as I unscrewed the wire plugs and attached the leads of the capacitor it was all good,
untill I brought the second lead, and touched the other wire (I was holding it by the insulation), I could see really small sparks, I thought, how is this possible, I just discharged the damn thing, and thats when my eyes followed the cord and I saw that I forgot to remove the plug from the wall!
so I had my hand on 120V wire for 5 minutes, and didn't get shocked (lucky), if my hand made contact with the other wire(unlucky) then I would be in a world of hurt,

thats why from that day on, one hand rule and keep the plug in your pocket when working on something.
THATS IMPORTANT (I also accidently (yeah right) try to discharge a capacitor while I once agian, you guessed it, forgot to unplug the plug,

that was the coolest thing I ever saw...(gaint white light and molten metal showers of sparks on the floor)
unforchunatly, my dad was in the room, and I got yelled at. (to my suprise the breaker didn't kick.) so I learned to respect mains the hard way (and avoided death a few times.)
good thing I use insulated arc rods and screw driver to short capacitors and not just a piece of wire.

and my floor now has a permanent burn in it (hardwood).

moral of these stories is, some extra safty precautions will avoid equipment and personal damage.
also I think the comp didn't die because of the surge arrestor on the wall outlet and the inbuild filter.
as for the breaker not kicking, I dont know, but the lights when dark and then came back up.

radiotech

Sat Jan 30 2010, 07:01AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
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Posts: 1546

The idea of PFC is good. We had lots of those big yellow syncronous motors running at 6600 volts with the load uncoupled
just to give needed Megavars. They are neat. At one critical DC current in the rotor PF =1, increase it it becomes a capacitor, lower it, it becomes an inductor. named 'syncronous capacitors'.

The meters on the panels were Zero center--Megavars in-out
and Megawatts in-out (out only when steam drove it and it became an alternator.

quicksilver

Sun Jan 31 2010, 07:52PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Absolutely - the worst shock I've had was when I was 20 yrs old working in a machine shop and brushed against a VERY large grinder with a 4hp motor running 240v. I was young, in VERY good condition and had been shocked before. This thing was entirely different. I believe I brushed against it with my elbow in a slight extremely fast touch.

I seriously felt like I was being thrown like a rubber ball; my muscles contracted so violently that I ended up about 15 feet away and could barely stand. I actually thought that someone had struck me or that I fell; I just could not conceive of what happened until I was told.
This (IMO) was extremely dangerous, as I really didn't comprehend what happened of what I could have done to prevent it.

There is something about current that is magical and not always in a positive conception.

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