Voltage drop especially in 3 phase system is due to low 
power factor.Low power factor leads to increase in I2r 
losses which in turn increses the regulation.As regulation 
increases voltage drop occurs which directly effects the 
efficiency of generation and increase in stress of 
transmission line.Thats why KEB people who are responsible 
for maintaining required voltage put fine if we maintain 
low power factor.Corona and skin effect are negligeble .