The Insulating Properties Of Castor Oil And Its Applications In The Tesla-transformer-type Pulse Generator

The insulating property of dielectric plays an important role in the performance of pulsed power generators. In this thesis, the microsecond pulse insulating properties of castor oil are studied, under different electrode conditions, pulse repetition rates and the hydrostatic pressures. The application of castor oil in a Tesla pulse generator system is analyzed. The detailed work includes the followings:1. Design and simulation of a breakdown test system for castor oilA test cell is designed, in which the electrode gap can be fine-tuned, with the precision of 0.01 mm. There are voltage and current sensors in the cell. Common problems during the experiments, such as the electromagnetic interference, the surface flashover on high-voltage side of cell and maintaining the state of the dielectric between the electrodes, were solved by means of shielding, immersing the cell in insulating oil and circulating the oil respectively. The experiment results agree with the numerical simulation.2. The statistical analysis of the factors affecting the castor oil breakdownWeibull distribution model is selected to analysis the results of castor oil breakdown. Under near uniform fields, the experiment results show breakdown field for castor oil is about 20 kV/mm for DC and 73.5 kV/mm for single pulse condition. Under non-uniform fields castor oil shows higher breakdown field when the needle electrode is positive. The relation of breakdown field with the effective electrode area obeys the 0.27 and 0.18 power law when the needle electrode is positive and negative, respectively. With increasing rep-rate, the breakdown voltage decreases, while the jitter increases; the breakdown electric field of castor oil is increases with the repetitive rate to the -0.12 power. With increasing hydrostatic pressure, the breakdown strength increases with the hydrostatic pressure to the one four power. The impact of hydrostatic pressure on castor oil is greater than that on the deionized water.3. The application of castor oil in the Telsa–type pulse generatorTraditionally transformer oil is used in a Tesla pulse generator. The application of castor oil requires different optimizations. The experiment results show that the output voltage of the load of the single pulse mode is 332.6 kV, and the output pulse width is 10 ns, and the maximum charging voltage of the PFL is 397.8 kV, and the output electric power is 1.08 GW. Under the repetition conditions, the output voltage of the load is 250.4 kV, and the output pulse width is 10 ns, and the data variance is 11%. Compared with the transformer oil PFL, the output pulse width of the castor oil PFL is increased by 40%. This proves that castor oil can be used for compact generators.