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Re: Designing safety from the beginning.

In a message dated 11/4/98 7:46:32 AM Pacific Standard Time, tesla-at-pupman-dot-com
writes:

<< 
 I am getting ready to build my first Tesla Coil and am considering safety
 issues.  I have decided that before I begin looking for transformers,
 capacitors, etc., I should give some thought to safety and how the safety
 concerns should be reflected in the control panel I am designing.  With
 this in mind I have a few questions for the group.
 
 1.  Has anyone had any success in using a dead man's type switch as the
 main power switch for the coil.
 
 2.  Am I right in my assumption that my main power switch should be in
 the AC line leading to my transformer and not on one of the higher
 voltage lines?
 
 3.  Has anyone successfully and safely discharged the capacitor(s) using
 a switch on the control panel?
 
 4.  Would it be possible to design the main power switch so that in one
 position it would turn the power on and in the other it would drain the
 capicitors?  Would this work better with a three position switch?  (For a
 "null" position in the middle.) Would it be better to do this with two
 differently rated switches?
 
 5.  With regard to safety, are there any gauges, meter's, etc. which
 should be designed into the control box?
 
 Thanks, 
 
 
 Alex >>

Alex,

Glad to hear we have a new Tesla coil builder in the works.  Folks have used a
dead mans switch on the main control panel.  You definitely want to switch the
240 (or 120v) mains coming into the system.  I switch both legs of the 240 v
line then go through AC line filters then into the variac.  For meters you
would like to have at least a volt meter and current meter to monitor the
inputs to the H.V. transformer.  I have read where some coilers have used high
voltage relay schemes to discharge the tank cap when power is switched off.
In a traditional Tesla coil set up, the cap will discharge back through the
primary of the Tesla coil and the secondary output of the H.V. transformer.
The cap and primary are in series and connected across the secondary of the
H.V. transformer with the spark gap also across the H.V. mains (in parallel)
and located physically close to the cap and primary.  Discharging the cap(s)
becomes an issue when using an equi-drive tank circuit with two capacitors,
one in each leg of the tank circuit (one connected to each side of the tank
circuit primary coil).  For this design, you can have high voltage, high value
resistors mounted across the caps which would discharge them with a reasonable
waiting period.  Maybe someone using this design can give you more
information.

Ed Sonderman