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
A phase sequence is an order or sequence in which the currents or voltages of different phases attain their maximum values. In a three-phase system, there are only two possible phase sequences: R-Y-B (positive Phase Sequence) and R-B-Y (Negative Phase Sequence).
EXAMIANS