[TriEmbed] Power Supply rail current

[Jeffrey Crews]

Asking more for my own education than as a suggestion: could a large enough
capacitor prevent the arcing across the contacts as the relay opens and
closes? And if so, how large a capacitance would it take to handle this
much current?

jsc


On Wed, Jul 9, 2014 at 8:01 AM, Adam Haile <email at adamhaile.net> wrote:

> Ok, yeah, that's what I was thinking. I wanted it to be normally open and
> then energize the relay to close and provide power. That way when I turn
> the supply on, nothing is connected by default. But I assume I still have
> to be worried about the contact welding in that scenario since I might
> already have the device drawing power hooked up (I would rather not have to
> disconnect it every time I start up the supply).
>
> Also, I think I found my power rails:
> http://www.amazon.com/dp/B000H9JRI0/ref=biss_dp_t_asn
> 1/8" x 1/4" copper bar stock. My calculations show this should be able to
> handle WAY more power than I need. And it's pretty cheap. Figure I'd just
> do a slightly wider than 1/4" trace and then solder this on top.
>
>
> On Wed, Jul 9, 2014 at 4:19 AM, Scott Hall <scottghall1 at gmail.com> wrote:
>
>>  On 07/08/2014 05:50 PM, Adam Haile wrote:
>>
>> So,  let me make sure I understand this...
>> When you say have the relays energized, I know you mean energize the
>> solenoid but do you mean by that that the relay contacts are closed (power
>> flowing) or open (no power)? I'm guessing you mean don't go from open to
>> closed while there's power flowing since their will be a temporary arc?
>> Could I just use a normally closed relay and then use the microcontroller
>> to open the relay and cut the power if I need to.
>>
>>
>> For safety reasons, you want the relay to disconnect if energizing power
>> is removed.  An NC contacts will not break the circuit if you have power
>> control problems to the energizing coil.
>>
>>
>>  Do you have any links to those higher cost relays? I would really love
>> to actually make it so that I could have a button on the front (hooked to
>> the uC) that would allow me to, using the relay, turn the power on or off
>> to any of the outputs. So having one of these nicer relays, if not too
>> expensive, might be nice.
>>
>>
>> Look up "contactors" for relays designed for high currents and regular
>> switching.
>>
>>
>> --
>> Scott G. Hall
>> Raleigh, NC, USAScottGHall1 at GMail.Com
>>
>>
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>>
>
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