PCB tracks

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Can anyone help, I have to layout a PCB with
tracks carrying 240VAC @ 16A!!, what is the
width of track I would need for 2oz copper
track length is around 50mm.
Also what track spacing etc for 240VAC is required.

Thanks

Phil




Re: PCB tracks

For track widths: http://www.geocities.com/CapeCanaveral/Lab/9643/TraceWidth.htm
Note the different widths for internal and external tracks. The internal ones
are those inside a multilayer PCB or encapsulation.

For track spacing: http://www.vutrax.co.uk/xbook3.htm



Quoted text here. Click to load it


Re: PCB tracks

Quoted text here. Click to load it

I'd be careful there, Trevor. 1mm? Sounds way too low to me. What about allowing
for creepage, and high voltage transients that can be expected on the mains?
There are two areas for consideration really; isolation from the mains to the
"user" side, where the above are important, and between adjacent high voltage
tracks on the mains side.

Have a look at the section "Track Clearances for High voltages" on
http://www.vutrax.co.uk/xbook3.htm#voltage

Brian


Re: PCB tracks
Quoted text here. Click to load it

As someone else has pointed out, these spacings are for electrical
insulation only, *not* for safety.  If it's a safety issue, the
spacings will be much larger, but never having done anything with
high voltages connected directly to anything remotely mains-like
I've never looked at the requirements.  If you are doing something
in which breakdown accross the insulation could be a cause for
safety concern, then you're going to have to do lot more research
than asking in a newsgroup, I'm afraid!

Trev

--
Trevor Barton
Isotek Electronics Ltd, 9 Clayton Wood Bank, Leeds, LS16 6QZ, UK.
We've slightly trimmed the long signature. Click to see the full one.
Re: PCB tracks
@titan.btinternet.com:

Quoted text here. Click to load it

I appreciate that the contact is rated to switch that, but things are
different if the opened contact is to be used as a means of isolation of
the equipment. Most small relays cannot be used (irrespective of their
rating) because the air gap is <3mm when the contact is open. Now make
sure that your relay is ok, then see about your tracks! It is not good
practice to depend on *any* PCB insulation if the contact is a means of
isolation, so you may find that you have to fit an external isolating
switch.

--
Mick
http://www.nascom.info for Nascom & Gemini info.
We've slightly trimmed the long signature. Click to see the full one.
Re: PCB tracks
your thread has now already 6 answers and none of them is your correct
answer. You can calculate current, temperature and those things for your
track but these formulas are only valid for low voltage traces.

In 230V AC main the question is to be short circuit proof. You mentioned a
16 Amp. Fuse and you should know the loop resistance in mOhms of your
complete supply to calculate something. You have to start with the
resistance of your wall outlet. Messure voltage without load, apply a
reasonable and known load, then meassure voltage again. With the
difference you can calculate the practical existing resistance of your
wall outlet. In addition, there is your PCB now.

The interesting thing is, what happens if there is a short circuit behind
your PCB. This depends from the fuse characteristics and what the other
loads in the 16 Amp. circuit are. In case of short circuit in mains, there
is a short time with currents much above the theoretical 16 Amp. The
practical value depends from your total loop resistance and is in the
range of a few milliseconds up to a few hundred milliseconds in the range
of kiloampere. Your task with the dimension of your track is to make
shure, that kiloampere peak blows the fuse instead your copper trace.

Only one thing is shure: If you calculate with 16 Amp you are definitely
wrong. Therefore see the risk of short circuit and consider the posibility
of additional fuse to protect your PCB. If not possible, support the trace
with a copper wire or make a plane shape and connect the thermal pads with
minimum 4 legs. Distance between L1 and N should be minimum 8 mm and
remember: Its prohibited to feed the protection earth (PE) over a PCB
trace.

Re: PCB tracks

Quoted text here. Click to load it

From what I remember about the regulation in this area, and backed by
the other answers in this thread so far, I think I can summarize it
all into this statement:

    If you don't already know the answers to these, you are
        absolutely *not* the person to be doing this PCB design.
    Stop that work right now, and get professional help.

You'll need consulting by someone who actually knows how to do this,
or you'll have to drop the project.  Usenet may be a great resource of
information, but not a substitute for real knowledge where people's
heath or even their lives are potentially at risk.  Don't bet your
income on Usenet recommendations, ever.

You're in serious danger of hurting yourself or others if you get this
wrong, and nothing short of actual know-how backed by a formal
education and a certificate will leave you in a position where you can
even remotely afford the risk of bringing such a thing to market.

--
Hans-Bernhard Broeker ( snipped-for-privacy@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

Re: PCB tracks
Quoted text here. Click to load it

Come on, people die from cancer, strokes, heartattacks, caraccidents,
not from a bad designed power supply. Life is full of risks, so build
that power supply. 10mm wide tracks, 6mm apart. No problemo. Use formal
coating if used in industrial enviroments.

--
Thanks,
Frank Bemelman
We've slightly trimmed the long signature. Click to see the full one.
Re: PCB tracks
Quoted text here. Click to load it

No, people do die from bad power supply designs, although it's pretty
rare these days I'll grant, but that's due in large part to there
being formal specifications and regulations.  There is a happy medium
somehwere inbetween the IMHO over cautious view of Mr Broeker and the
somehwat cavilier view of Mr Bemelman.  The OP should now have enough
information to go look at some formal standards, and then lay out his
PCB in the knowledge that he is being both competent and careful.  In
that respect, USENET was a good place to start.  It's up to him now to
take the infomation we've given him and turn it into a good design, and
he now has enough information to start to be able to figure out how do
so, which is more than he had before he posted.

Trev

--
Trevor Barton
Isotek Electronics Ltd, 9 Clayton Wood Bank, Leeds, LS16 6QZ, UK.
We've slightly trimmed the long signature. Click to see the full one.
Re: PCB tracks
Quoted text here. Click to load it

Mine too Frank, but you and I are not a lawyers.

Quoted text here. Click to load it



Re: PCB tracks
Quoted text here. Click to load it

Not only do people die from badly designed power supplies in most parts
of the world there is a lot of legislation on power supplies for
equipment.

You may find yourself open to prosecution even if it does not go wrong.

Regards
         Chris


/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills  Staffs  England    /\/\/\/\/\
/\/\/ snipped-for-privacy@phaedsys.org       www.phaedsys.org \/\/
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

Re: PCB tracks
bericht
Quoted text here. Click to load it

Kids like stacking things. Give 'm ten 9V batteries and see what they
can build with that. Pure innocense can build a lethal weapon, and it
is for sale in every shopping mall.

So, use your common sense. Build decent stuff. But don't turn a mice
into an elephant.


--
Thanks,
Frank Bemelman
We've slightly trimmed the long signature. Click to see the full one.
Re: PCB tracks
Quoted text here. Click to load it

The local law takes precedence over any "common sense" and there is a
lot of legislation for power supplies.

/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills  Staffs  England    /\/\/\/\/\
/\/\/ snipped-for-privacy@phaedsys.org       www.phaedsys.org \/\/
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

Re: PCB tracks
Quoted text here. Click to load it

Certainly. However, reviewing the original posting, I see nothing to
indicate the application of this power supply. It might be going into
consumer equipment. Assuming *any* level of common sense on the part
of the appliance-buying public is sheer unmitigated insanity.
("Caution! Hot Apple Pie will be hot after heating!").

Also, if I buy an industrial system of some kind (say, a
speed-controlled pump for volatile liquids), I expect that the
manufacturer has taken all appropriate safety precautions.

I'm not directly predicting any dire outcomes, just gently pushing my
opinion that you were being a little cavalier and devil-may-care. The
answer to the question "What's the worst that could happen?" is
"Almost anything".

Site Timeline