Corona Discharge

Understand the phenomena that occur in the windings of turbine generators, hydroelectric generators, and large electric motors. The steps taken by the manufacturer to reduce this electrical aging have been checked. Power transmission usually handles high voltages because of the need to transmit a lot of electrical energy from the power station to the load center. At such a high voltage, an effect called the corona effect is introduced. Because this corona effect causes electrical energy loss, the corona machine is called a corona discharge.

Corona discharge is generally accompanied by audible noise of hissing or breaking, visual purple light, ozone gas generated around the conductor, power loss and radio interference. When a potential difference is released between two conductors, a potential gradient (or electric field) is established in the air. This potential gradient is large on the surface of the conductor. Under the influence of this potential gradient, the existing free electrons in the air achieve a large speed. Because of cosmic rays, ultraviolet rays, etc., some free electrons always exist in the air. The greater the applied voltage, the greater the potential gradient, and therefore the greater the velocity of free electrons.

When the potential gradient on the surface of the conductor is large (about 30kV/cm), the existing free electrons rush to the air molecules at a fast speed to remove one or more electrons. Therefore, cumulative ionization of the air adjacent to the outer surface of the conductor occurs, and the part of the ionized air also conducts electricity.