SSC JE Electrical 2019 with solution SET-2
If a circular conductor carries a current of ‘I’ ampere having radius ‘r’ meter, then the magnetizing force at the center of the coil is given by
Magnetic Field Strength (H) gives the quantitative measure of strongness or weakness of the magnetic field. H = B/μo Where B = Magnetic Flux Density μo = Vacuum Permeability The magnetic Field strength at the center of circular loop carrying current I is given by B = μoI/2r B/μo = I/2r H = I/2r At/m Where r = Radius
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.
Average speed:- The distance covered between two stops divided by the actual time of the run is known as average speed. Average speed = (Distance between stops)/(Actual time of run) Schedule speed:- It is defined as the ratio of distance covered between two stops and the total time of run including the time of the stop. Schedule speed = (Distance between stops) /(Actual time of run + Stop time) This shows that schedule speed is always smaller than the average speed. The difference is large in the case of urban and suburban services and is negligibly small in the case of main-line service.
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
EXAMIANS