The shaft torque (Tsh) in a d.c motor is less than total armature torque (Ta) because of ……………. in the motor.
Right Answer is:
Iron and Friction losses
SOLUTION
The torque is developed in the armature and hence gross torque produced is denoted asTa.
The mechanical power developed in the armature is transmitted to the load through the shaft of the motor. It is impossible to transmit the entire power developed by the armature to the load. This is because while transmitting the power through the shaft, there is a power loss due to the friction, windage, and iron loss. The torque required to overcome these losses is called lost torque, denoted as Tf. These losses are also called stray losses. The torque which is available at the shaft for doing the useful work is known as load torque or shaft torque denoted as Tsh.
∴ Ta = Tsh + Tf
The shaft torque magnitude is always less than the armature torque, (Tsh < Ta).