Characteristics of electrical tree and effects of barriers on electrical tree propagation under AC voltage in LDPE

LDPE has been widely used in electrical insulation and high voltage device application. In this paper we have studied the characteristics of electrical tree aging at AC voltage in LDPE, with the continuous applied voltage to observe the propagation of electrical tree. The electrical tree experiments were carried out with needle-plane specimens. At the same time the barriers of different polymer films were introduced into the LDPE between the needle and the plane electrodes and we compared characteristics of electrical tree propagation of pure LDPE with LDPE with the barriers. The results show that electrical tree propagation can be slowed down by introducing the barrier between two electrodes, meanwhile, this is capable of increasing time to breakdown significantly. The effect depends upon the barrier of different polymer films used, their structural and the binding forces of the interface to the surrounding LDPE and polymer films.