RE: Calling electrical experts - Din rail PSU 240vac to LV dc

["Hawes,Timothy Edward \(GEG\)" <haweste@xxxxxxxxxxxxxxx>]

> -----Original Message-----
> From: uktiggs  Sent: 24 November 2004 12:38
>
> Hi,
>
> I am fed up with the number of plug pack PSUs which require
> numerous mains sockets and take up so much space.....
>
> I have gone through the loop of one plug pack per output
> level and splitting the outputs with terminal block - still
> don't like it as it looks messy.
>
> I have thought about using one big powerful DC PSU to drive a
> concoction of regulators giving individual outputs at multiple (maybe
> adjustable) voltages. I think someone else on the list has
> done this but I have decided against this due to time etc.....
>
> So my solution is going to be to purchase some DIN rail
> mounted PSUs and put them in an enclosure with a cable exit
> feeding into tunking.

http://rswww.com p/n S82K-03012 for e.g.,
or 373-0344
There's loads on RS, I searched for "DIN power supply"

> Overall it will probably be no better than my array of plug
> pack type PSUs but it appeals to me on the basis of being
> neat, tidy and, I think, a little more compact than the
> current solution.
>
> Anyone got any comments on this?

Sounds like a good idea to me :-)

> My question for the electrical experts is:

I'm not a *qualified* expert, but can share what I know of the panels we
do for work :-)

> I am worried about the mix of Mains supply and Low Voltage in
> the same space.... My intention is to have a single cable for
> 240v coming into the enclosure which will terminate into a
> standard 13A plug.

Our control panels at work have this, the standard solution is to use a
cable that is rated for the highest voltage you'll see in your enclosure
- we typically use "Tri-rated switchgear cable" see: http://rswww.com
search for part # 364-461 and you have a whole selection of colours to
choose from :-) That p/n is 1.5mm cable - check what size you really
need for what you're powering.

> Inside the enclosure I will need to split the supply to each
> PSU. I will probably need to increase the number of outputs
> from each PSU.
> What, from a professional point of view, would be the best
> way to address these considerations? Terminal block? If so is
> it possible to get it to mount in a tidy fashion on a rail?

Again, in our panels, we use http://rswww.com p/n 425-190 (or similar)
You can jumper adjacent terminals together using p/n 268-1645 or 425-320
These terminals are designed for top-hat style DIN rail mounting.
Ideally you'd ferrule the ends of the cables, see http://rswww.com p/n
452-473 for an appropriate tool & bootlace ferrules.

> Is there some form of rail mounted bus bar I could use? Are
> there any regs concerning what happens inside distribution
> boards etc. which would apply in this case?

In general, we try to keep mains away from low voltage for safety, and
interference reasons. Good practice dictates that you'd label everything
really well, and that you'd maybe choose one colour of wire for LV (we
use gray) another for 110V, another again for mains (although you're
probably just as well sticking with normal mains wiring colours to avoid
introducing additional confusion. Do a proper drawing for the panel, and
keep a copy of that drawing readily to hand so you don't guess things if
you have to go back and modify / maintain the system.

> Thanks for any help you can give.
>
> Regards,
>
> David

Good luck, and . . . . PHOTOS !! when complete please ;-)

Any questions, just shout.

Tim H.