Re: Need a little experiment carried out....
Quote:
Originally Posted by
irving2008
Hmmmm hadn't though about that. Should be powering both windings in parallel then?
If we're just using it as a load, since it doesn't look like we can get useful information from the other phase, then yes I tend to agree. Also you wouldn't get rated power with just one phase energized.
Quote:
Originally Posted by
irving2008
Maybe, but a dropping weight and pulley is easy to calibrate
Yep, could even use dropping a weight to calibrate the other system.
Re: Need a little experiment carried out....
It's great seeing you two "talking dirty" with one another again :wink:
Re: Need a little experiment carried out....
Quote:
Originally Posted by
Jonathan
Just spotted something interesting...
I measured the back-emf voltage from the 3.1Nm stepper motor at 1200rpm and it's 66 volts, so using those numbers k=0.525 Vs/rad. The unit Vs/rad is dimensionally equivalent to Nm/A ... i.e the 'torque constant' of the motor, so we can use this to find the torque for a given phase current. Rated phase current is 4.2A, so for both phases T=2^0.5*4.2*0.525=3.12Nm. That matches the holding torque specification rather nicely, so maybe this could be a simple way to find the rated torque of stepper motors. Or more usefully, use the formula for phase current (something like i(t)=V/R-(V/R-I)*e^(-t/(L/R))) multiply by k to get torque as a function of time then integrate to get the mean torque and then the torque vs speed curve for the motor. I think this should be more accurate than the usual approximation.
Yea i would have to agree with what he said....because i don't have a clue....what he just said....:stupid:
Quote:
Originally Posted by
WandrinAndy
It's great seeing you two "talking dirty" with one another again :wink:
Agreed, all we need now is the shaft size equations to come into it...:ambivalence:
.Me