In a message dated 8/28/2005 2:58:20 P.M. Central Standard Time,
k8isk@comcast.net writes:
Hello to the group,
Has anyone in the group ever used solid state relays for controlling the AC
input to a power supply for a 1500w amplifier? I recently acquired some
really nice 50A @ 480VAC solid state relays and they would work great in a
power suppy but never using this type device before, I am somewhat hesitant.
Thanks for any info.
73, Terry
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Hi Terry, I have used many Solid State Relays for HV power supplies over the
years with excellent results. At first I tried 25 amp units and had a couple
of failures due to the very high peak currents in my capacitor filter power
supply. After switching to 40 amp units no more problems.
I do use fault sensing in the amplifier to interrupt the control voltage to
the relay in the hope that quick hv turn off will help keep more components
(including the relay) from failing.
The only other comment is that the solid state units need to be mounted in
such a manner to help remove self generated heating. There is a voltage drop
across the relay of about .7 as I recall and you can see that with large peak
currents some heating will happen. The relays I have used have a small leakage
when turned off that leaves a few volts ac on the transformer primary. This
means you could have a bit of voltage left on the hv side when you might
think there is none. Beware, shorting the filter is deceptive: it will just
charge right back up.
73,
Gerald K5GW
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