Factors Affecting Corona Loss

Corona loss depends upon numerous factors like system frequency, system voltage, air density, surface and size of conductor etc.

These all factors are discribed as follows:-

A. System Frequency :- As we seen the in peeks formula and petersons formula corona loss directly proportional to the system frequency.

B. System Voltage :- Electric field in the space arround the conductors depends on potential difference between the conductors. When potential difference increase the electric field increases and therefore power loss due to corona increases.

C. Density of Air- Corona loss increases with decrease in air density that means corona loss inversely proportional to density of air. Corona loss in a transmission line which passes through a hilly area than that when same line passes through plains. It is due to reduced value of delta at high altitudes.

D. Conductivity of Air- Conductivity of air depends on number of ions, per unit volume of air, size and charge per ion. These factors very with altitude and atmospheric conditions. It means, in a rainy season, numbes of ions increases and atmosphere becomes more conducting. When conductivity increases, corona loss increases.

E. Conductor surface and Conductor Size- Potential gradient at the surface of stranded conductor is greater than that for equipment solid conductor, so corona loss is more for stranded conductor. Also corona loss increases.

F. Load Current- Conductor heats up due to flow of load current. Heating of conductor prevents the depositions of dew or snow on the surface of conductor and reduce corona loss. During rains,heating of conductor has no effect on corona loss, but after rain heating of conductor accelerates the rate of drying of conductor surface. Time for which rain drops, remain on surface is reduced and so corona loss is reduced.