Alternator Data Interpretation

Hi,

I came through the following parameters for alternators.

1. Stator Winding: Double layer lap

2. Rotor: Dynamically balanced

3. Wave form distortion: No load < 1.8 %, non distorting balanced linear load < 5 %

4. Telephone Interference Factor: Better than 50

5. Total Harmonic Factor: Better than 2%

Questions:

1. What is the advantage of double layer lap ?

2. Are not all rotor dynamically balanced? Why it has to be mentioned specifically in specification ?

3. What is non distorting balanced linear load <5% ?

4. Why telephone interference factor better than 50 ?

5. Why total harmonic factor better than 2% ?

Regards,