[Amps] Working on my Darwin award

[Vic Rosenthal]

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 at gmail.com>
> To: "Amps reflector" <amps at 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