Powerdump relay (now with free arcwelding)

Hi all,

I have a RELAY configuration on my PSU whereby the power being shut off
(E-stop / limits / etc) causes the transformer to be disconnected and
the capacitor to be dumped through a power resistor. The problem I am
getting is that the relay has been arc-welding itself in the ON-Position
(and lately in the off-position).
The old RELAY was rated 20A, and the PSU was a 55V/500W linear one, with
the power resistor calculated to dissipate 10A.

I'm about to install a relay rated at 30A N.O and 3A NC (The best I can
seem to find for this voltage range) and was wondering if I could use
some of the capacitors I have spare for preventing DC brush-motor
spikes, to somehow limit the arcing?

Any advice?
Thanks!
Abby