RE: 24V (was apartment grounding)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Rich" <rdjmgmt@xxxxxxxxxx>



Jim

Well I thought having a 24v control system in my power control unit
would provide me a small level of protection. My 24v deadman switch runs
the out put relay. The 120v line runs thru standard 20amp line filter,
type in a 3x3 metal box, it then goes thru the Variac, then the relay,
last thru 50amp line filters , 2.5 dia x 5" long. The 50 amp filters are
to RF ground. Both sides of the line going from the Variac are fused
also with neon indicator lights on the control panel that will light if
the fuse fails.

Rich , from Missouri


Subject: RE: apartment grounding (was: I'm a newbie coiler!- apartment
coiling)

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 05:59 PM 3/14/2006, Tesla list wrote:
>Original poster: "Rich" <rdjmgmt@xxxxxxxxxx>
>
>
>
>Having an electrical background like you do just keep you eye open for
a
>small 24v control transformer and a relay , run your system through a
>remote lead and rig it switch as a deadman, it only works when you push
>the button and then you only have 24v near you.

Haven't seen many 24V control transformers that will hold off 100kV.

The risk (not huge, but something to think about) is the following
sequence:

HV from secondary flashes over, creating moderately low impedance
connection between 110V side of transformer to 24V side of
transformer (or, worse, between TC primary with 10kV on it, to 24V
side of transformer)

Current flows from 110V (or 15kV) through you.

You lie there twitching and/or smoldering, unable to let go, as the
arc burns happily, roasting you.

A bit extreme, I grant you, but there's a lot to be said for being
able to disconnect without having to get near ANY wires connected to
the system.  Or, more to the point, so that someone else, who's
freaking out at seeing you thrashing about yelling "turn it off! For
the love of mike, turn it off!" will be able to render the system
safe.  Nothing discourages a would be helpful bystander like getting
shocked by the power switch.

Naturally, if your partner is a cool, calm, collected coiler that's a
member of this list, they'll casually walk over and turn off the
switch with the insulated "hot stick" they always carry (never know
when you might need it!), while berating you for damaging the finish
on your new coil, then calmly restart your heart, and then, of
course, log in to tell us all about it.