[Amps] soft start circuits

[PAUL HEWITT]

The SSR manufacturers recommend MOV's at the line side terminal to avoid
DV/DT turn-on.
Cheers, Paul

PAUL HEWITT
WD7S PRODUCTIONS
QRO HOMEBREW COMPONENTS
http://wd7s.home.att.net


> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]On
> Behalf Of David Lisney
> Sent: Thursday, January 08, 2004 9:05 AM
> To: amps at contesting.com
> Subject: [Amps] soft start circuits
>
>
> Hi, I have used soft start in a big 13.8v power supply, it uses
> much the same VA rating transformer that a medium sized linear
> would use (about 2500-3000VA).  In my example mains (240v) is
> initially applied via a large 50ohm metal clad resistor, when the
> rails are about half way up a solid state relay conducts
> operating a large contactor, thereby applying full mains directly
> to the transformer.
>
> The whole control is by just two push buttons, one to "start" and
> one to "stop"... one minor bug is that the lightly loaded solid
> state relay has once operated by itself, probably due to a mains
> transient, and the power supply has powered up by itself, hardly
> a major concern in a fully enclosed low voltage power supply but
> not something you'd want to trust entirely. This glitch has only
> occurred twice in maybe 10 years but still not acceptable for a
> high voltage supply.
>
> Maybe I will revise the design to "ramp up" using sequentially
> operating solid state relays, the contactor does make an irritating hum!
>
> 73 de Dave G0FVT and Happy New Year
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps