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Unread 07-02-2012, 10:50
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Ether Ether is offline
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Re: RS-550 current draw

Quote:
Originally Posted by Jon Stratis View Post
I've got a question for the brilliant minds here at CD... How much current is too much for a 550 when running it at full speed (not stalling) for 2+ minutes? In other words, any idea what the limit is before you burn out the motor?

On our shooter, each 550 is drawing about 7A when the shooter is at full speed (and 8-9A when it's spinning up the flywheel to get to full speed).
First, a point of clarification: if it's drawing 7 amps, it's not running at "full speed". I think you meant "full voltage applied". It's running at 93.3% of full speed. That's faster then the max efficiency point and generating less waste heat (watts_in minus watts_out). So at that speed, the motor should be able to run continuously, assuming it is vented properly!

Read this:
http://www.chiefdelphi.com/forums/sh...72&postcount=5

Code:
Motor Calculator  build MCALC32ab 1/19/2012 610pm

M5-RS550-12 (-B) @ 12.00 volts:

@ free (no load):
   oz-in      Nm     rpm    rpm%    amps   watts out    watts in    eff%
     0.0   0.000   19300   100.0     1.4         0.0        16.8     0.0

@ stall:
   oz-in      Nm     rpm    rpm%    amps   watts out    watts in    eff%
    70.5   0.498       0     0.0    85.0         0.0      1020.0     0.0

@ max power:
   oz-in      Nm     rpm    rpm%    amps   watts out    watts in    eff%
    35.3   0.249    9650    50.0    43.2       251.5       518.4    48.5

@ max efficiency:
   oz-in      Nm     rpm    rpm%    amps   watts out    watts in    eff%
     8.0   0.057   17105    88.6    10.9       101.4       130.9    77.5

Select input:
1)oz-in  7)watts_in    3)rpm    5)amps   8)eff%
2)Nm     6)watts_out   4)rpm%   9)volts  a)rpm&ozin   5


enter amps: 7

M5-RS550-12 (-B) @ 12.00 volts:
   oz-in      Nm     rpm    rpm%    amps   watts out    watts in    eff%
     4.7   0.033   18007    93.3     7.0        62.9        84.0    74.9

Last edited by Ether : 07-02-2012 at 11:07. Reason: added motor calculator "print out"