Torque in a DC Machine


Torque is the rotational force that causes an object to rotate. In a DC machine, the torque is generated by the interaction between the magnetic field and the current flowing through the armature winding. The magnitude of the torque is directly proportional to the product of the armature current and the magnetic flux.


Torque Equation

The torque equation of a DC machine is given by:

T = k * φ * I

Where:
- T is the torque
- k is a constant factor
- φ is the magnetic flux
- I is the armature current


Torque Induced is Zero

When the torque induced in a DC machine is zero, it means that the rotational force is not present or negligible. In other words, there is no torque being produced by the interaction between the magnetic field and the armature current.


Zero Current

If the torque induced is zero, it means that the armature current is zero. This can be understood from the torque equation:

T = k * φ * I

When T is zero, it implies that either φ or I (or both) must be zero. Since magnetic flux is usually not zero in a DC machine, the armature current must be zero to result in zero torque.


Conclusion

Therefore, it can be said that if the torque induced is zero in a DC machine, then the armature current is zero. This conclusion is based on the torque equation, which states that the torque is directly proportional to the product of the armature current and the magnetic flux. If the torque is zero, it implies that either the current or the flux (or both) must be zero. However, since flux is usually not zero, it can be inferred that the armature current is zero.