Solid state tesla transformer for flashover test on suspension insulators

Abstract

This paper presents design and construction of a dual resonant solid-state Tesla transformer (DRSSTT) used for an electrical flashover test of suspension insulators. Rated voltage and frequency of the developed DRSSTT are 120 kV and 200 kHz, respectively. The developed DRSSTT was designed and constructed by applying solid-state electronics devices and knowledge of power electronics together. The developed DRSSTT has over advantages over the conventional Tesla transformer (CTT). The CTT has high power loss from the ignition caused by sparks of electrode of quenching gap, a cooling system requirement, large structure, high weight and high cost. In addition, it is not convenience to be used for the flashover test in a small testing room in the actual factory and on-site test. Therefore, the DRSSTT is necessary to develop. The aims of developing the DRSSTT are to be used to perform the flashover test of insulators and to reduce the equipment cost. The developed DRSSTT uses H-bridge inverter to drive a conventional Tesla coil. Four IGBTs in H-bridge configuration are employed to generate a square wave voltage with a resonant frequency which is close to the resonance frequencies of the primary and secondary circuit of Tesla transformer. Therefore, the voltage regulator, the high-voltage transformer, and the quenching gap are not required in the developed equipment. So, the developed DRSSTT are small size and low cost. However, there are weak points of the DRSSTT such as requirement of high rate current and voltage of electronics switching devices. The experiments have been carried out to confirm the performance of the developed DRSSTT. In the experiments, the developed DRSSTT with the height of 0.6 m was employed in the flashover test of insulators. The damped high-voltage with high-frequency of about 200 kHz is generated to make continually flashover on an insulator for 3 second to 5 second. The insulators under test are suspension type ANSI 52-1, ANSI 52-4 and post type ANSI 57-2. It is found that the DRSSTT can generate high voltage with frequency about 200 kHz (180 to 201 kHz) and make flashovers on the insulators according to the ANSI C29.1 standard. From the reasons above, the developed DRSSTT is very attractive to use for the flash test of insulators in the real practice.