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2,5kW NST

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LAN_403

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Wed Feb 15 2006, 10:39AM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

Yeah, i tuned my NST and got incredibly Results.

Normally, its a 6kV 120mA NST , unpotted, i removed the shunt and now i have nearly 2,5kW Power and more.

I think the output current will be around 400-500mA by 6kV . I tested it with my Variac on 200Volt input, with a maximal current of around 14,5A. i cant go higher with the voltage (ie 230Volt) cause i tripped the 16A Breaker a few times by drawing an arc, and i dont want to wrack my variac, which is only rated at 12A.

the secondary windings are staying cool, very funny, everything seems to work fine. Now i have a question. Can i measure the exact output current of this monster? or is it only possible to calculate it? i need to know it relatively exact, cause i want to build my next SGTC using this Transformer.

heres a video showing the Arcs i can draw up to 5" . The Amperemeter is showing the current.

...

Wed Feb 15 2006, 03:14PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

I have a feeling that if you were to try runnung it at that power for any extended period of time, especially in a tesla coil, the windings will overheat...

As to the video... Are you crazy?!? That red alligator clip has 5kv on it and it is touching the primary and the table... That pvc wire is not rated for the 7kv peak to peak, and sooner or later it will break down and you will get an insanely nasty ark (this is not connected to mains, so the current is limited only by the resistance/inductance of that halt the secondary...

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Wed Feb 15 2006, 04:19PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

the red alligator clip doesnt touch anything, maybe in the video it looks like this, but i take care of such things, i dont want to burn my nst. and every contact has 3kV on it.
so the alligator clip is on the table which is out of plywood, what should happen

Part Scavenger

Wed Feb 15 2006, 05:51PM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

Just run the HV though a multimeter just like if you were testing the primary side. I've sent over 30kV though mine with no problems. Steve Ward explains why this is possible on the old forum, but I don't remember where. Oh, and I wouldn't use a good meter though I've never had a problem. Make sure it's on the ampere function first or it will kill your meter!

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Wed Feb 15 2006, 06:02PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

mhh, bad expierience with that, i dont want to test it , i destroyed a dmm the same way a year ago.

Marko

Wed Feb 15 2006, 08:56PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Multimeter will 'see' only voltage drop on his shunt and nothing more.
It depends on current, voltage of source actually doesnt exist for multimeter.
If we try to measure volts a huge voltage drop will apeear across multimeters high internal resistance and blow it in small pieces.

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Wed Feb 15 2006, 09:12PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

i already said, that i dont want to measure it that way, cause i already wrecked a dmm that way, and i have no "cheap" multimeter lying around, sorry.

no other way to measure the current the "safe" way?

HV Enthusiast

Wed Feb 15 2006, 09:26PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

wrote ...

Just run the HV though a multimeter just like if you were testing the primary side. I've sent over 30kV though mine with no problems.

Although this will work, it is generally a very bad idea to do this for several reasons:

1. Safety - Your meter is potentially floating at a very high voltage. Remember, someone where i worked was killed doing something similar to this. Even the most careful people in the world make a mistake sometimes and would accidentally pick up that meter.

2. Safety - You may think measuring at the GND side is safe, but this is even worse than number 1 because it provides a false sense of security and may think you can safely handle the meter. But should you accidentally lose the GND connection, you have full voltage on your meter.

3. Equipment - Very easy to damage and destroy your meter this way.

Sure, it will work doing it this way, but not the smartest things to do.

wrote ...

no other way to measure the current the "safe" way?

Sure, measure current on the primary side. Not the most accurate way of doing it, but should get you close enough to what you are looking for.

Self Defenestrate

Wed Feb 15 2006, 09:32PM

Registered Member #87 Joined: Thu Feb 09 2006, 01:36PM
Location: San Jose
Posts: 191

What about an analog panel meter?

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Wed Feb 15 2006, 10:35PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

mhh, okay, i already measured the current on the primary side, but i cant believe that its really so high.

the transformer is rated at 6kV output by 220volt input. per volt input i get 27,7volt output , i measured at 200volt so my secondary voltage should be 5540 volt.

then my highest primary current by drawing an arc was ca 14,5 A , so 14,5A *200V=2900Watts , so 2900/5540V=0,52 A secondary current.

. that is very much, especially cause i know at 230volt input, i trip the 16A breaker when i try to draw an arc.
when i run the nst on 230 volt i will get 6277volts secondary , current draw of around 16A+
16A*230=3680Watts. 3680/6277=0,58A , that is incredible high

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