This report describes the air breakdown characteristics in plane-plane and
sphere gap electrode configuration under lightning impulse. The breakdown in air
(spark breakdown) is the transition of a non-sustaining discharge into a selfsustaining
discharge. In electrical power system, high voltage power equipments are
mainly subjected with spark over voltage. This over voltage which may causes by the
lightning strokes, switching action and so on. In this project, two different electrodes
(plane-plane and sphere gap) are used to study the air breakdown characteristics.
This two electrodes are tested by using different gap start with 0.5 cm, 1.0 cm until
2.5 cm. Refer to British Standard BS EN 60060 that explained detail about the
general definitions and test requirements for high voltage test techniques to construct
in this project. In addition, TERCO lightning impulse circuit are use to obtain the
lightning impulse waveform. To estimate U50 during the experimental, up and down
method are used with the value of n ≥ 20. Finite element method magnetic software
(FEMM) is use to shows the potential higher electric field occurs around the
electrodes. Vector and contour around the electrodes also can be viewed. From this
project can conclude that electric field distribution between two conductors (or
electrodes) depends on applied voltage (U50), gap between electrodes, types and
surface of electrodes. In the end of this project, the relationship between voltage
(U50) and gap, electric field (|Emax|) and gap, field utilization factor (η) and gap, U50
and field utilization factor (η) and electric field (|Emax|) and field utilization factor (η)
have been constructed with help of graph.