On 2/23/2014 12:42 AM, Bill Turner wrote:
ORIGINAL MESSAGE: (may be snipped)
On 2/22/2014 6:35 PM, Paul Christensen wrote:
Another one:
Years ago (early to mid 60's, I had an HT44/SX117 combination on a bench
about 30" high down in the basement. I needed to measure the plate
current which was done across a resistor in the PS. They had two jacks
for the meter probes on the PS.. My meter was left over from an
electronics course. I had to work cross armed to the meter and probes
and I had to get up on the desk. I had to move the meter to get a
better look at the reading, so I reached across with my right hand to
the metal meter handle. Unbeknownst to me at the time, my fingers in my
left hand had slipped down onto the probe. (the meter case was also
metal, which left one hand on 540 VDC ans the other on ground. I
remember it hitting me and my next memory was waking up on the tiled
concrete floor gasping for breath. I can only surmise that landing on my
back, started my heart because I was gasping for breath. I finally
crawled up into the easy chair where it took at least 15 minutes to
catch my breath and get to the point where I was willing to try and
stand. Couple days later I purchased a Simpson 250.
BTW there were pits in the chassis where it arced from my finger tips.
They were tender for a while, but no real damage.
I apparently had taken a header off the 30 inch high bench and
apparently landed flat on my back on a tiled, concrete floor.. No lumps
or sore spots on my head, or sore neck muscles. OTOH my chest felt like
I'd been hit with a big hammer for a few days. Having been on my knees,
I figure I fell around 4 feet.
73
Roger (K8RI)
I could see a situation where if the Variac is left at a point just
below the relay pull-in threshold, the resistors could bake open, even
if they are fused.
Paul, W9AC
REPLY:
That's a good point. The answer IMO is to do the variac ramp up quickly,
say in about two seconds or so. That should give you time to watch the
line current and HV. The ramp up should be to full power, i.e. don't
pause partway up.
If the step start resistors blow under that circumstance I'd say they
are under rated anyway.
73, Bill W6WRT
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|