Re: [CAD_CAM_EDM_DRO] Re: Power supply softstarts

Graham Stabler <eexgs@...> wrote:



It needs to be a box that just gets turned on. I don't want knobs
to turn and the associated weight.

The fact I am using servos has nothing to do with it, the softstart
is for the inrush on the primary of the transformer.

/// I thought that was only an issue with some stepper drive systems popping a drive on start-up. And aren't the Capacitors in the system to tame the secondary side of the power supply? And we put a cap at each drive to absorb any spikes? If the inrush is not having any adverse effect on the system. I'd let it thunk. Welders clunk every time they start for many years. It's not harming the transformer. ////

For the record I am in the UK on 240v

Graham




--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers
wrote:

> How about a 110volt 10 amp variac on the primary? Strat the power

supply at a low setting then gradually increase it. They can be had
pretty inexpensively. With servos, I dont think this is an issue.

>
> Ron
>
> Graham Stabler wrote:
>
>
>
> I am building a 6 axis system with linear servo motors and have
> bought a pair of 500VA transformers which should provide 50v and
> sufficient amps for peak acceleration. I have also got a 100,000uF
> capacitor for smoothing although I may increase this.
>
> On my previous homebrew power supply I added a softstart that
> charged the output capacitors via a resister until they were up to
> voltage. The prevents a nasty thud on turning on the supply.
> However I have a feeling that with the two transformers in this
> supply in parallel I may have more of a problem with the

transformer

> inrush current which does more than make a thud!
>
> What is the "best" way to produce a soft start on the primary of

my

> powersupply. Should I just use a contactor, timer and power
> resister to provide a current limited supply to the transformer on
> power up?
>
> Thanks in advance for any help
>
> Graham
>
>
>
>
>
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