Torque or moment or moment of force is the tendency of a force to rotate or move an object about an axis. A force is a push or pull, likewise, torque is a twist to an object. Mathematically, torque, T = F × r.
Let- Tg = armature or gross torque (N-m) = Force × radius.
- r = radius of the armature in m.
- N = speed of the armature in rpm = N/60 rps.
Work done/revolution = force × distance moved per revolution
The expression for voltage in dc motor is given by,
Electrical input = electrical power equivalent to mechanical power developed + armature copper loss
Mechanical power developed,
Since equation (1) = equation (2),
Hence torque of a dc motor is directly proportional to the flux/pole and armature current.
Relation between Armature Torque (Ta), Shaft Torque (Tsh), and Loss Torque (TLoss) :
We know,
The motor output is,
Loss Torque = Armature Torque - Shaft Torque
For more detailed explanation check out the below video -
