Statically induced EMF in armature due to absence of compensating winding

Explanation:
Compensating winding is a winding that is installed in the stator of a synchronous motor or generator. The function of this winding is to counteract the effect of armature reaction. When a generator is loaded, the armature current produces a magnetic field that interacts with the magnetic field produced by the rotor. This interaction causes a distortion of the main magnetic field, which results in several problems such as the reduction of the output voltage and the generation of harmonics. However, the compensating winding produces a magnetic field that opposes the effect of the armature reaction, maintaining the main magnetic field constant.

Effects of absence of compensating winding:
If the compensating winding is absent, the following effects take place:

- Statically induced EMF in armature: The absence of the compensating winding causes the armature reaction to distort the main magnetic field, causing a change in the flux linkage with the armature coils. This change in the flux linkage induces an EMF in the armature that is not related to the rotation of the rotor, but to the armature current. This EMF is called statically induced EMF, and it can cause several problems such as overvoltage, overcurrent, and insulation breakdown.

- Reduction in the flux: The absence of the compensating winding also causes a reduction in the main magnetic field, which results in a reduction in the output voltage. This reduction in the flux can also cause the generator to lose synchronization with the grid, which can lead to a blackout.

Conclusion:
In conclusion, the absence of the compensating winding in a synchronous generator can cause several problems such as statically induced EMF, reduction in the output voltage, and loss of synchronization. Therefore, it is important to install the compensating winding in the stator of a synchronous generator to counteract the effect of armature reaction.