Re: Tracing exploding wire waveform with Tek 2235 (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sat, 23 Dec 2006 12:52:15 +0900
From: Peter Terren <pterren@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Tracing exploding wire waveform with Tek 2235 (fwd)

I have a lot of waveforms on my site related to can crushing capture using a 
Rogowski coil and an analogue storage CRO then photographed.  The discharge 
characteristics and ring down are clearly seen for currents up to 100kA.
I get nervous measuring anything from the hot terminal.  It is just one more 
place for things to go wrong in a hurry.
Note that voltage will only give you a certain amount of information and you 
will have difficulty getting true current measurements using voltage drop 
across a resistor for example unless you really understand inductance 
issues.
I don't know your CRO but either it is a storage one and you take a photo of 
the screen at your leisure, or it is a conventional CRO and you have to set 
up a time exposure on your camera (it needs to have manual controls to do 
this).
Either way it takes you concentration away from the safety issues.  I was 
concerned to hear about not using the ear muffs.  Forgetting the ear muffs 
is only a problem with your hearing.  Other mistakes may not be as 
forgiving.  Do you wear safety goggles at all times when charged?  They will 
only provide marginal protection.  I have had to dig out copper wire 
embedded in wood which would have penetrated to bone if it was my face.

 I know one experimenter who had a contactor malfunction and blow up while 
he was close and now no longer does this stuff. Someone else has a video of 
an unintentional firing. You must take precautions to keep yourself away 
when it is charged.  Even if it is not charged as exploding wires may not 
result in full discharge and there is always to issue of recovered charge 
after hour or days which is up to many hundreds of volts and lethal too.

Peter
http://tesladownunder.com

> ---------- Forwarded message ----------
> Date: Fri, 22 Dec 2006 11:41:55 -0600
> From: Igor Chudov <ichudov@xxxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: Tracing exploding wire waveform with Tek 2235
>
> [This message has also been posted to sci.electronics.design.]
> I have a Tektronix 2235 scope.
>
> http://igor.chudov.com/projects/Homemade-TIG-DC-to-AC-Inverter/01-Prototype-1/dscf0005.jpg
>
> I also have a hell machine for making high voltage discharges.
>
> http://igor.chudov.com/projects/High-Voltage/Hell-Machine-THUMPER/
>
> I also have a Beckman 50kV high voltage divider probe for high voltage
> linemen, similar to this.
>
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130053095020
>
> What I would like to do, is capture on the oscilloscope screen, the
> waveform of the occurring discharge. I want to keep it for a while to
> be able to get to the scope and take a photograph.
>
> I only used my scope before for watching continuous waveforms, never
> for one shot.
>
> I guess my main question is does anyone know how to trigger the scope
> by the discharge and then let it keep the waveform on the screen, is
> that even possible with 2235.
>
> thanks
>
> i