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Insulation resistance test related issues

time:2020/11/30   source:华天电力  reading:236 time

1. Why can the megohmmeter be widely used in the insulation performance test of high-voltage electrical engineering equipment?


The insulation resistance value can effectively reflect the moisture, pollution and serious overheating and aging defects of the overall insulation, and the use of a megohmmeter to measure the insulation resistance is simple, safe, clear in concept and cheap, so it is used in the insulation of high-voltage electrical equipment , There are the following obvious shortcomings:


Insulation Resistance Tester


(1) The megohmmeter is widely used in the general DC mega-edge test.


However, the voltage of the megohmmeter to test the ohmmeter is below 2.5KV, which is much lower than the working voltage of some enterprise electrical engineering equipment. When equipment management has defects for certain products, the leakage current capability under high voltage is much larger than that under low voltage, that is, the resistance of insulating material under high voltage is much smaller than that under low voltage.


(2) Generally, the output current of a European meter is 2 mA. When the equivalent capacity of the test equipment is large (for example, power transformers, generators), the charging speed is slow and it is difficult to measure accurate data.


2. Why do some of our electrical equipment need to test the insulation resistance and pass the test polarization curve?


Measuring insulation resistance is one of the simple methods to understand the insulation of electrical engineering equipment. Large-capacity samples can reflect the insulation technology of the samples more accurately and timely by analyzing the absorption ratio and polarization development index of the measurement system. The curve is the relationship curve of the relative value of the insulation resistance over time, which can more accurately reflect the insulation of the test product. Therefore, for certain large-capacity test products of the enterprise, the insulation resistance of the equipment must be tested, and the polarization curve must be tested.


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