Ferro Resonance

Resonance involving transformers was first reported in 1907 and the word ferroresonance was coined in 1920.

Ferro resonance. The most common condition in which it causes disturbances is when the magnetizing impedance of a transformer is placed in series with a system capacitor. Basically ferroresonance involves series connection of saturable inductors and system capacitance due to shunt capacitor banks series capacitors internal capacitance of transformers overhead lines and cables. Figure 1 a situation where ferroresonance may occur. The purpose of this paper is to identify the root causes of ferroresonance phenomena occurring in the power systems along with its implications on the transformer during no loading and loading conditions.

The cable capacitances form three parallel l c elements that are in series with each other and the source voltages. Ferroresonance is a resonance phenomenon caused by the nonlinear inductance and system capacitance. The term ferroresonance was used for the first time in 1920 for express the oscillating phenomena in an electric circuit. The temr ferro resonance refers to a special kind of resonance that involves capacitance and iron core inductance.

Ferroresonance became a noted problem in the 1930s when. Ferroresonance or nonlinear resonance is a type of resonance in electric circuits which occurs when a circuit containing a nonlinear inductance is fed from a source that has series capacitance and the circuit is subjected to a disturbance such as opening of a switch. This happens when there is an open phase conductor. It can cause overvoltages and overcurrents in an electrical power system and can pose a risk to transmission and distribution.

The abnormal rates of harmonics and transient or steady state overvoltages and overcurrents that it causes are often dangerous for electrical equipment. It does not normally occur in distribution systems but certain conditions may be established such as an open phase during single pole switching. The results of the technical investigation. For better understanding of ferroresonance it is worth to remind the linear resonance in lrc circuit.

The effect of sunspot cycles and those of nuclear explosions can be mitigated through the use of three limb transformers with a large air gap between the transformer iron core and the tank 31. Ferroresonance is worthy of mention however because it can utterly destroy a transformer. Ferroresonance can be avoided by employing gas sf 6 filled cables 30 for distribution systems above 20 kv. Ferroresonance is a nonlinear resonance phenomenon that affects power networks.

Some unexplained breakdowns can be ascribed to this rare non linear phenomenon.