# Electric motors newbie questions

Discussion in 'Electronic Basics' started by Scale, Jun 21, 2007.

1. ### ScaleGuest

Hello, I'm a newbie and I'd like to learn a little about electric
motors.

I've had a run-through of electric motors and I understand the basics
(how they work, that they are an inductive load, etc), but I've got a
few questions:

1. Is there an easy equation or way to find the torque that the the
motor will give out for a given load and voltage/current etc?

2. What information is understood from a motor constant and how is
this found for an arbitrary motor (say, one that I've aquired and wish
to understand but have no spec sheet for)

3. What is a blocked rotor test (besides some sort of test that is
done while blocking the rotor.. I.e. what is measured?) and what is
understood from this?

Maybe I'm just not looking in the right places, but I can't seem to
find any plain English information on this.
If someone could even point me to a good website or something I'd be
extremely thankful.

Cheers,

Matt

2. ### BobGGuest

I assume you are interested in dc motors with brushes? And permanent
magnets or wound field? Or brushless? Or ac? Are you interested in
design rules of thumb... how to pick the right speed/torque/power for
a certain application? I guess we all assume the basics.... watts is
volts x amps and power is torque x speed. More volts -> more amps.
More amps-> more torque.

3. ### Guest

UR intrested in DC well the moter principle is deprnds on

T=rXp (torque=rdies x power)
Same principle applicable here The total ac mesured in P=IxV
so in moter the magnatic brush produce required power as above
explination.