Ampere works law or Circuital Law This law relates to work done in a magnetic circuit i.e. closed magnetic flux path. The work done on or by a unit N-pole in moving once round any complete path is equal to the product of current and number of turns enclosed by that path
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
The transformers which are particularly designed to provide electrical isolation between primary and secondary circuits, without a change in voltage and current level are called isolation transformers. The turns ratio of such isolation transformers is 1:1 i.e N1 and N2. Hence, isolation transformers are also called 1:1 transformers. The isolation transformer greatly reduces any voltage spikes that originate on the supply side before they are transferred to the load side. Some isolation transformers are built with a turns ratio of 1:1. A transformer of this type has the same input and output voltages and is used for the purpose of isolation only. The main function of the isolation transformer is to reduce the voltage spike before it reaches the load.
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.
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