Re: [CAD_CAM_EDM_DRO] Power Supply

rpbfire wrote:

>Hello all. I am newbie to this group, have lurked for a while and
>now going for my first post. I am retrofitting an early 80's
>Bridgeport Seriies II that had a BOSS 9 control. I am using Rutex
>servo drives and plan on running Mach2 control software. My
>question has to do with the DC power supply that the machine came
>outfitted with. I hope to reuse it as it seems to fit my
>power/voltage requirements and it would save me money. My problem
>is that I am getting some higher than expected voltages out of the
>24 VDC bridge rectified supply. I would like to continue to use
>this to power much of my air systems and to supply the control
>voltage to the Rutex cards. I have 247 VAC coming from my single
>phase mains. This is higher than the 230 VAC that the machine is
>set up and transformers tapped for. My father works for the local
>power company and says that I live very close to the sub-station,
>thus the high main voltage that I will have to live with. My supply
>is set to accept 115VAC from a transformer and turn it into 24VDC.
>I am getting 127 VAC or so from the transformer and 36 VDC out from
>the supply. THis seems like a big jump out for the relatively small
>jump in.
>

The reason is that you are using a capacitor-input filter, which
delivers the
peak of the sine wave. A 24 V RMS sine wave has a peak 1.414 times
higher, that is 33.9 V. So, your results are exactly as expected. If you
need 24 V DC, you should use a transformer with a 17 V RMS output.
The relays probably don't take a lot of current, so you could just add
a separate transformer for the 24 V DC stuff.

Jon