1. The impact of weather
In high humidity conditions, the corona loss of the leads greatly increases, while the interference of the surrounding electromagnetic field also increases, resulting in a decrease in the Q value.
When the temperature is high during the experiment, the equivalent resistance of the circuit greatly increases, thereby reducing the Q value.
2. The impact of test time
As the test time prolongs, the equipment is heated, the equivalent resistance increases, and the Q value also shows a downward trend. This phenomenon is very significant on hot summer days, and the equipment often needs to rest for 30 minutes before continuing to use.
3. The impact of reactors
If the reactor is placed on metal components such as iron plates, eddy current loss is formed and the equivalent resistance increases.
4. The Influence of Choosing a Better Resonance Point for High Voltage Test Frequency on Q-value
In application, it has been found that when the voltage rises close to the test voltage, the speed of voltage rise is too fast and accompanied by significant voltage fluctuations, which can even lead to voltage protection action, making the test must restart. This is detrimental to equipment safety. However, if the voltage protection value is set too large, it cannot effectively protect the tested equipment from overvoltage. Therefore, it is generally recommended to lower the test voltage to a good resonant frequency at 2% of the test voltage, Afterwards, adjust the frequency slightly below 40% of the test voltage to avoid the above phenomenon.
5. The influence of high-voltage leads
When conducting AC voltage withstand tests on individual electrical equipment, due to the small capacitance of the test object, the influence of high-voltage leads on the test is not significant. When conducting AC withstand voltage tests on outdoor distribution devices as a whole, the installation height of the equipment increases with the voltage level. The higher the voltage level, the longer the high-voltage lead. Generally, high-voltage leads are longer, leading to increased corona loss and an increase in equivalent resistance in the circuit. The stray capacitance formed by them is connected in parallel to the measured capacitance, resulting in a decrease in the resonant frequency of the circuit and a decrease in the Q value; At the same time, the interference of the surrounding electromagnetic field also increases, causing a decrease in Q value. Therefore, when conducting AC withstand voltage tests on high voltage electrical equipment, it is recommended to use corrugated high voltage leads as much as possible.
Therefore, when conducting AC voltage withstand tests, in addition to relying on the good performance of series resonance, attention should also be paid to voltage equalization measures, such as selecting wires reasonably, arranging the test site reasonably, arranging time reasonably, etc. Heat dissipation and dehumidification methods can also be adopted to reduce the impact of equipment heating and moisture on the Q value.
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