Quote:
Originally Posted by FoleyEngineer
Hi Kevin,
Where do you get this figure from? I'm looking at the performance curve for the CIM and it looks like at 40A it's generating about .8Nm of torque which works out to .59 ft-lbs, or about 7 in-lbs - not 25 in-lbs as you suggest.
Maybe I'm mistaken. Wouldn't be the first time! Anybody?
Thanks!
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You're correct, that was a typo on my part, or some such. I intended to use the 100 oz-in at 40A figure you can get from the CIM dimension sheet, which puts it at
6.25 in-lbs. I used that figure in the rest of the math, however, so the ratio still stands.
Quote:
Originally Posted by Jonathan Norris
Looks like he is taking about stall torque, which is a bit less then 25 in-lbs. Yes we run 40A breakers, but the amperage will spike a lot higher then 40A before the breaker trips. From my rough understanding with 40A breakers on a CIM we can get all the torque out of the motors. The only time I can remember hearing the breakers trip is stalling our drive against a wall...
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You can't get anywhere near stall torque out of the CIMs. The circuit breakers, Victor/Jaguar, and motor will all eventually prevent you from doing so. In the past, FIRST has arranged things so it's the circuit breaker that keeps you from using stall torque for any length of time, to protect your investment in your motors and speed controllers. Rest assured, that circuit breaker trips somewhat before your Victor would melt, and that your Victor would melt before your motor did. But the motor would most certainly do so if you stalled it for too long.
The 40A breakers we use will trip in at most 0.6 seconds at the 133A that stall torque would draw, so it's not really available for a useful amount of time, beyond stating up.