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Unread 06-03-2016, 21:52
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VacioArconte VacioArconte is offline
Appreciator of Robots
FRC #2468 (Team Appreciate)
Team Role: Electrical
 
Join Date: Feb 2014
Rookie Year: 2012
Location: Austin, TX
Posts: 41
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Re: Prototype Power Distro /Robot Operating Amperage?

Quote:
Originally Posted by Brayton View Post
Okay so I work mainly on the mechanical end of things for our team, so bear with me here as I muddle my way through my explanations. My electrical knowledge is limited to essentially things that run off of 5 and 3.3V (i.e. micro controllers).

I am working on designing a power distribution board for prototyping during build season, to avoid me looking like this when we try to power up a single motor: https://i.imgflip.com/k06v7.jpg

Anyway, I was trying to decide what switches to use, I wanted a simple Enable/Disable, possibly a polarity swap (which yes would require multiple switches), and maybe even a voltage readout. So the functionality is relatively irrelevant it is the rating of the switches I need to know. I understand the main power distribution board on the robot has 30A and 40A fuses but I can't believe we are running things at 12V DC at 40A, it just seems insane to me. I can barely find anything rated for that.

TL;DR
- Do FRC Bots actually run at 30-40A?
- Do I need an extremely heavy switch to use as a pass through from battery to a motor (i.e. Full CIM)? (enable/disable)
- If the above is true where can I get these? Would a simple light switch from Home Depot work?


If you have any questions feel free to ask, thanks for the help in advance!
I can't speak to your last two questions since I haven't personally used any (non light) switches rated for the high currents of FRC bots, but I can tell you that FRC bots do indeed run at 30-40A, and technically even higher. If you check the stall current for a CIM (http://www.andymark.com/Motor-p/am-0255.htm), you'll see that they can draw up to 133A. Now, you might ask why we have 40A circuit breakers if CIMs are running at such a high current. The thing is that 40A circuit breakers can allow current higher than 40A, but only for a limited time (http://www.andymark.com/product-p/am-0288.htm). A simple google search returned these switches rated for 50A (http://www.wiringproducts.com/50amp-toggle-switches).

Hope this helped!