# How to calculate No load current and No load torque in DC Motor



## AMIanna (May 20, 2010)

As I found, the curve for armature current-torque and speed-torque curves is as shown the link below : 
http://www.globe-motors.com/dc_motor.pdf

How to calculate no load current and no load torque from the equation given for permanent magnet motor?
I have problem to plot Ia versus Torque, because I need to get the value for I no load, to make sure the current is not equal to zero when torque is zero.


----------



## John Valdes (May 17, 2007)

Can I ask where do you work and why are you asking such complicated questions? Are you a student, trying to impress your supervisors or are you an engineer?
For the no load current - Measure it. It will not be a constant value. 1HP or 2000 HP? Which one? The term no load torque is not in my vocabulary because it means sqat in the real world. Torque is the amount of energy required to turn/twist the armature. We use full load torque to size motors for certain applications, or to cross reference DC to AC or visa versa.. I have never had to figure no load torque because it has no effect on operation.

(Torque in lb.ft.= HP x 5250 dived by RPM). This formula is all I would ever need in a real world application.


----------



## AMIanna (May 20, 2010)

Thanks to u, John for replying my thread.

1) where do you work?
Malaysia, UPM.

2)why are you asking such complicated questions?
I need to analyze the best model from 64 models of BLDC ( Brushless motor), in producing high torque, for agriculture application.

3) Are you a student, trying to impress your supervisors?
Yes. Im Master student, but im not trying to so..
I really need to know the related equation especially to find no load current. I need to get data theoretically, before i run an experiment to get experiment data.

4)are you an engineer?
I was. n now futher study.


----------



## wildleg (Apr 12, 2009)

try posting your question on mike holt - there are a couple guys there that are very knowledgeable on motor theory, but don't have the balls to hang out here.


----------

