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DC high voltage generator polarity conversion

time:2021/2/24   source:华天电力  reading:249 time

There is a very popular power test instrument in the mining, metallurgy, steel, and power sectors. Its name is DC high voltage generator. It has a very powerful function. It can perform DC on high voltage electrical equipment such as zinc oxide arresters, power cables, transformers, and generators. High pressure test.


The polarity conversion of the DC high-voltage generator involves a series of processes such as generator voltage reduction, grounding, silicon stack polarity switching, grounding and boosting. Each step of the polarity conversion process requires a lot of time. In order to shorten the polarity switching time of the DC high-voltage generator and realize fast polarity switching, it is necessary to shorten the time of each process.


DC Hipot Tester.png


Several ways for DC high voltage generators to realize fast polarity conversion:


1. Accelerating the step-down speed in the step-down process is one aspect of shortening the polarity switching, mainly by increasing the discharge resistance to speed up the step-down speed. Increasing the discharge resistance does not increase the total resistance of the discharge resistance, but increases and divides the voltage. The number of resistors with the same resistance value connected in parallel, the larger the number of bars, the smaller the total resistance and the faster the voltage drop. At the same time, the lower limit of discharge resistance should be considered, because too small discharge resistance will inevitably lead to an increase in leakage current during normal operation of the device.


2. In the grounding process of the grounding switch, it takes a long time for the test voltage to be grounded to zero or zero. When the DC high voltage generator voltage drops from the test value to a certain level, the direct grounding of the fast grounding switch can greatly shorten the grounding process of the grounding switch. However, the fast grounding switch that meets the high voltage requirements can withstand all high voltages and large currents, which is extremely demanding for the fast grounding switch.


3. To put it simply, the silicon stack needs to achieve fast polarity switching to realize the polarity switching of the internal single tube. In order to achieve this goal, we must first consider the motivation. At present, there are three simple powers, driven by electric, pneumatic and hydraulic methods. According to the structural characteristics of the DC high-voltage generator, it is impossible to achieve power supply under high pressure. The pneumatic device has the compression ratio of the air source used by the cylinder.


If all silicon reactors are connected in series through the gas pipe, when the humidity in the gas is high, the entire equipment will be discharged from the gas pipe, causing equipment damage and so on. The hydraulic method uses vacuum-treated alkylbenzene insulating oil without causing emissions. Secondly, the compression ratio of oil is much smaller than that of gas, which can realize the smooth polarity conversion of the silicon reactor and avoid the problems of the other two methods. In contrast, it can be seen that the hydraulic selection method is reasonable.


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