Re: HV accident (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Fri, 3 Aug 2007 18:43:06 -0700
From: Ray von Postel <vonpostel@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: HV accident (fwd)

Bleeder resistors should never be  installed and considered SAFETY 
DEVICES.  The are placed across the output of power supplies as part of 
the filter system to improve the filtering and regulation of the output 
voltage.  The second use is across a series string of capacitors to 
equalize the voltage across the capacitors.  This type of circuitry was 
seldom if never found in commercial equipment.  It was a "work around" 
when you didn't have a capacitor with the correct working voltage.

At one time I worked in high frequency (2 to 30 MHz) radio stations 
where it was necessary to often change the operating frequency of the 
transmitters.  This necessitated the turning off of the power, opening 
the metal cabinet, and using wrenches to change coils.  SAFETY required 
you to short the coils to ground and leave a grounding strap on them 
until you finished making the changes.  In one particular instance one 
of the guys got careless and failed to use the built in grounding 
strap.  The result was that he got fried by the 4000 volt charge on a 
bank of eight 2 Mfd capacitors.

The inquest decided he was killed because of his own carelessness and 
the fact that a 200 watt 5000 ohm wire wound bleeder resistor had 
opened up.  So much for bleeder resistors being a safety device.

Was he an idiot?  In my book, a very dead one.  Tesla coils are not 
defibrillators.

Ray


On Aug 3, 2007, at 8:00 AM, Tesla list wrote:

>
> He should have anticipated problems due to the lack of bleed resistors 
> or
> hands off discharging and that is poor planning.
> I applaud his candour,however, in describing his shock.