Consider the following statements :
- interpole windings are connected in series with armature windings
- polarity of interpoles must be the same as that of the main poles in advance
- distortion of the main field under the pole shoes is not affected by the use of interpoles
From above, the correct answer is
A. 1 and 2
B. 2 and 3
C. 1 and 3
D. 1 alone
Share your understanding of this question with the correct explanation.
The correct answer is C. The statements 1 and 3 are correct.
- Interpole windings are connected in series with armature windings: Interpole windings, also known as commutating pole windings, are connected in series with the armature windings. This allows the interpoles to produce the required flux for commutation in coordination with the armature current.
- Polarity of interpoles must be the same as that of the main poles in advance: This statement is incorrect. The polarity of the interpoles is opposite to that of the main poles in advance. This is necessary to aid in the commutation process. The opposite polarity of the interpoles creates a magnetic field that opposes the armature field in the region of commutation, helping to facilitate the reversal of current in the armature coils.
- Distortion of the main field under the pole shoes is not affected by the use of interpoles: This statement is correct. The presence of interpoles does not significantly affect the distortion of the main field under the pole shoes. The main purpose of the interpoles is to improve commutation by generating a counter-emf in the coil undergoing commutation. The main field distortion is primarily influenced by factors such as armature reaction and saturation effects, which are not directly related to the presence of interpoles.
Therefore, the correct answer is C, as statements 1 and 3 are correct.