RE: [CAD_CAM_EDM_DRO] Transformer Soft Start

The other portion that has not been mentioned is how big a cap is being
used. The transformer can be perfect, but if there is a very large
capacitor in the power supply you will also ge a huge inrush. I had this
problem with a setup using a 1500 va torrid transformer along with a
50,000 uf cap. Would pop the 20 amp breaker about 50% of the time when
it was turned on. Put in an inrush limiter and there has never been a
problem since.

Tim
[Denver, CO]
Sherline products at Deep Discount Now offering Taig
Mach1 & DeskCNC with credit card ordering
www.KTMarketing.com/Sherline

> -----Original Message-----
> Hate to disagree with both of you but...I saw exactly this
> problem on a PSU
> that I built a couple of years back - there was absolutely
> nothing wrong
> with the way it was wired up (single primary, and you have to
> try pretty
> hard to mis-wire a bridge rectifier & a capacitor), but I had
> to use a much
> larger mains fuse than I had expected in order to deal with
> the inrush
> problem. At the time, this was a simpler solution than using
> an inrush
> limiter (I didn't have one to hand, but I did have a bigger
> fuse) but I
> will fit one when I can remember to add one to my next
> components order &
> will then replace the fuse with one of the correct rating.
>
> Regards,
> Tony