This type of motor is designed to operate with the start winding and it’s series capacitor permanently connected to the supply. lt has two capacitors connected in parallel in the start winding circuit for starting purposes. The running capacitor is employed to correct the power factor. As a result, this motor has a higher starting torque as well as a higher efficiency. These motors are employed in sizes ranging from 375 W to 7.5 kW. The power factor of these motor is upto 80% to 100%.
The strength of a magnetic field is specified by the magnetic induction B or by the magnetic field strength H. A current I through a long, straight wire produces a magnetic field with strength H = I/2πr at a distance r from the wire. Given H = 1 A/m I = 10 A H = I/2πr 1 = 10/2πr r = 10/2π
Lap Winding:-In a lap winding the number of parallel paths (a) is always equal to the number of poles (p) and also to the number of brushes. In the given question number of poles is 4 hence the number of brushes will be 4. Wave Winding:- In wave windings, the number of parallel paths (a) is always two and there may be two or more brush positions.
While estimating the overhead lines, the first and last pole is always earth connected and after every 3rd electrical pole, the fourth pole is earthed. Therefore, the approximate number of required ground set = 4
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