Re: [CAD_CAM_EDM_DRO] resistor for power supply

cadcamcenter wrote:

> Hi all,
>
> So far all the suggestions for the power supply for drives shows the
> connection from the output of the bridge rectifier direct to the
> capacitor (some may have bleed resistor, LED etc in parallel)
>
> An power engineer (who may not have very much experience with CNC
> items) mentioned that there will a large current surge on initial
> power up (when V on cap is 0) and suggested putting a resistor. My
> interpretation of his suggestion
>
> rectifier R
> . .-----/\/\/\-----
> / \ |
> / \ _____
> / \ _____ C
> \ / |
> \ / |
> . \./---------------
>
> What does the list think? And if this is an improvement what kind of
> relationship R = function (C,I,etc) should there be between R, C etc.

Yes, you can do this. You will need to keep the resistor value quite small.

Probably no more than one Ohm. You can also use a positive temperature
coefficient resistor, known as a surge limiter.

Jon