[Amps] Working on my Darwin award

[Vic Rosenthal K2VCO]

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/