[TriEmbed] High Current Sensing

[Paul Holzworth]

Adam,
The other way to sense that much current is with a current transformer or hall effect sensor that clamps around the output cable.  That way you don't need to bother with PC traces to carry the current and you don't have to splice into the output of your commercial power supply.  You can Google "dc current sensor 100a" and a  number of choices show up.

Paul Holzworth


On Jun 14, 2014, at 12:02 PM, Adam Haile <email at adamhaile.net> wrote:

> Very nice :) Will check those out. I assume those that the board traces for the power pass-through would still have to be massive though?
> 
> According to the calculator in KiCad, 2.75 mil trace (OSH Park standard) for 100A and a 20C temp rise would have to be 56mm wide!
> And am I reading it right that these don't need a heat sink? I'm assuming because it's not a typical ultra low resistance shunt and has effectively no resistance, therefore little to no wattage absorbed?
> 
> 
> On Sat, Jun 14, 2014 at 11:50 AM, Fred Ebeling <FEbeling at ecpdesigns.com> wrote:
> Hi
>  
> I would recommend one of the allegromicro products.  They have evaluation boards and I actually
> use one to monitor my power supplies under development.  Its big advantage is its isolated and
> you only have to pass the power thru the device.  No voltage drop, no power loss.
>  
> http://www.allegromicro.com/en/Products/Current-Sensor-ICs/Fifty-To-Two-Hundred-Amp-Integrated-Conductor-Sensor-ICs.aspx
>  
>  
> Fred Ebeling
> ECP Designs
>  
>  
>  
> From: Adam Haile
> Sent: Saturday, June 14, 2014 11:35 AM
> To: triembed at triembed.org
> Subject: [TriEmbed] High Current Sensing
>  
> As those that saw my projects at the Maker Faire know, I work with a lot of high current LED projects. So I'm always looking for higher current supplies and my variable bench supply definitely doesn't cut it so I generally use supplies like the 5V/40A supply I used for my 24x24 matrix. But that is even a too little for some of the projects I have planned. I'm thinking about getting a 500 - 700W (@5V) supply (something like this: http://www.ebay.com/itm/370888481354) and building it out with a few more features. 
>  
> Mainly, I want to add built in current sensing that would be displayed on an LCD screen (likely all Arduino controlled). The supply itself would be unmodified - I'm not crazy. I would just add all that between the supply output and connectors on the outside of an enclosure I would build.
>  
> So, my main question is if anyone has any advice for how I could go about sensing this much current? I'm thinking about using something like the TI INA219 (http://www.ti.com/product/ina219) which, with the right shunt, should be able to handle it and would have a nice I2C interface. I'd also like to have 2 - 4 separate outputs, each with their own separate sensor... so each would need to handle up to 100A or so.
>  
> I realize that running the current through any PCB trace to the shunt would probably require insanely wide traces, so is there a good, high precision shunt that would work off PCB?
>  
> Basically, I don't know what I don't know, so I'd love any direction that could be given.
> 
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