| Power transformer is one of the most important and expensive device in the power industry, in which the oil-immersed power transformers are widely used. Once the partial discharge inside the insulation occurs, it will threaten the safe operation of the entire grid.The development of power transformer partial discharge is an extremely complex process. It is necessary to build a multi-sample wideband partial discharge platform with five branches simultaneously, study the law of development through a lot of tests, improving the work efficiency. Based on the pressurization test platform with multi-loop, test pressurization test platform, a mean to solve the oil circulation system sealing problems was constructed in this paper to simulate the real transformer oil passage loop. A trip apparatus based on partial discharge signal and frequency signal leakage operation was designed to solve the problem of different life five branches, including a trip circuit and actuators. Wherein the trip circuit includes a high frequency circuit and a low-frequency circuit, both have a voltage follower, filters, full-wave rectification amplifier, an integrator and a comparator. Moreover, a logic circuit and a set of action execution were commonly used in the circuits. The simulation software was used to analyze the feasibility of a trip circuit at first, then a good circuit simulation was produced and tested through adjusting circuit components. An action actuator was designed, which worked together to ensure that branch off near breakdown before operation.During the experiments, the high-frequency signals and leak signal that 50Ω non-inductive resistor produced tuned the threshold of high frequency circuits and low frequency circuit respectively. The results show that the partial discharge signal corresponding high-frequency circuit threshold may differ depending on the development stage of signal, while the leak signal corresponding threshold is fixed. |
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