Breakdown Voltage (BDV) Tester for Transformer Oil

Our methodology for making a BDV tester for Transformer Oil is: Firstly an AC supply of 230V and 50Hz is rectified into DC through the rectifier. Then this rectified DC works as an input to the inverter. The sinusoidal PWM is generated through the microcontroller whose frequency and magnitude is controllable. Two complementary pairs of SPWM pulses is applied across the gates of these MOSFETS. Switching frequency used for driving MOSFET gate is 10 kHz. The inverter generates a sinusoidal output that is filtered through an LC filter. Sinusoidal voltage waveform is obtained by using 2nd order LC filter. Its magnitude can be controlled by controlling magnitude of reference sine wave. The LC filter mitigates the high frequency harmonics and converts it into a pure sine wave. Now the magnitude of the sine wave is varies from 0 to 230V and applied to the high voltage transformer. The transformer steps up this voltage such that the output rises from 0 to 35 kV with a fixed rate of rise of voltage of 1kV/s. This slew rate can be changed to 2kV/s or 0.5kV/s according to the requirement. This high voltage is applied across the electrodes that are immersed in the testing oil. Voltage is kept rising and when the breakdown of the test sample occurs at a particular voltage, a flash over is observed. The circuit breaker is connected at the primary to interrupt the current when breakdown occurs. Circuit breaker immediately cuts the supply. The breakdown voltage is measured through a voltage divider and a digital meter. As soon as the breakdown occurs, the output voltage drops to zero. The high voltage at the meter just before The breakdown is the determined value of breakdown voltage at a particular distance between the electrodes. Now the distance between the electrodes is varied and breakdown is observed again. The value of the breakdown voltage varies with the distance between the electrodes. WE ARE ABLE TO PRODUCE A PERFECT SINUSOIDAL STEPPED UP VOLTAGE (TILL 35KV), BUT WE ARE UNABLE TO CREATE A SLEW RATE OF 2KV/SEC WITHT THAT SINUSOIDAL WAVE. LIKE SHOWN IN THE FIGURE.

[DGM]

So in other words, you used something to do something with a thing, and it worked perfectly, but not totally. Maybe it's a simulation, but maybe not?

Read what you wrote. Pretend you're someone else. Nobody has your code or your simulink model. Do you think anybody else knows enough about what you did to be able to troubleshoot your problem?

Your text describes a physical testing process when what you're probably trying to do is a simulation in simulink. You'll have to let others actually see your model if you want help with troubleshooting your model. I don't have a modern version of simulink anymore, so the best I can do is make your question answerable by someone who does.

Answer 1

[Joel Van Sickel]

Hello Hatim,

you don't actually ask a question or share model details. If you still want help, please ask a specific question and provide additional information so that we can be of service to you. I will be closing this specific issue until that happens.