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/
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