It's interesting how things combine to cause dangerous situations. I
think this happened because I am in the middle of packing some gear that
I sold and doing various other things, so my shack is a horrible mess. I
was working on the power supply in a very inconvenient place, in an
uncomfortable position. It was late in the afternoon, after loading and
unloading a bunch of recycled computers, so I was tired.
So, in addition to following all the rules about unplugging things and
using shorting sticks, etc., I think I will add a new rule about working
on HV equipment:
Clean up, put the tools away, make sure I have plenty of space and time
to work -- first. And do it in the morning!
On 2/22/2014 7:09 PM, Carl wrote:
Any more stunts like that Vic and they will be mailing your ashes to
Israel!
Carl
KM1H
----- Original Message ----- From: "Vic Rosenthal K2VCO"
<k2vco.vic@gmail.com>
To: "Amps reflector" <amps@contesting.com>
Sent: Saturday, February 22, 2014 8:41 PM
Subject: [Amps] Working on my Darwin award
Speaking of dangerous stupidity, here's what I did today. I was
testing my amplifier with different plate voltages, so I was changing
taps on the primary and secondary of the plate transformer. At one
point I manged to connect the 240v line between the 220 and 240 volt
terminals instead of 0 and one of the others!
When the time delay expired there was a loud CLUNK as the 20A breaker
on the power supply, the 25A one on the wall of my shack, and the 30A
one in the service entrance all popped. I unplugged the PS and went
around resetting the breakers. Then I corrected the wiring and plugged
it in again.
Some of you may know what's coming. I think I heard a faint hum (it's
a quiet Dahl transformer) but the meaning didn't register -- until I
saw the HV meter on the amp indicating 3.4 kV, with the power supply
supposedly off!
The surge had welded the contacts of the HV relay (rated 30A). Not
surprising, considering the amount of current that probably flowed
through the #10 wires connecting my shack to the service entrance.
Although I spotted the problem before it killed me, this wasn't cool.
It also proves that I need a more serious contactor for a HV relay!
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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--
Vic
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