[Amps] A funny thing happened at the turn of the switch...

[Radio WC6W]

  I recently reconfigured a 3KW load bank, which I use
for amplifier power supply testing, by adding a 4
position progressively shorting switch to select 1
thru 4, 12K paths resulting in a selectable 12K, 6K,
4K, or 3K ohm load.
 
  This worked well until I ran the voltage up around
3KV where I noticed a disturbing tendency for the
switch, even though it has 1/4" spacing between the
terminals, to arc when the load is hot switched to a
higher resistance.  Said arc is maintained and is only
extinguished by removing power.

  My first thru fourth thoughts to remedy this
anomally are:  

   1.  Reposition the switch vertically and put an oil
filled jar over the terminals.

   2.  Use compressed air or a fast fan to blow the
arc(s) out.

   3.  Add Capacitor/Diode/Resistor snubbing networks
across the terminals, using something on the order of
1uF for the C.

   4.  Use a vacuum relay to switch the load bank out
when the switch is in transit.  This requires an
external power source for the relay.

  Does anyone have a better idea?  Or experience with
a similar situation??

73 & Good afternoon,
  Marv WC6W

http://wc6w.50webs.com/







*


      ____________________________________________________________________________________
Get easy, one-click access to your favorites. 
Make Yahoo! your homepage.
http://www.yahoo.com/r/hs