Why Y capacitor capacity can not be too large

The Y capacitor is a capacitor that is connected between the two lines of the power line and the ground (L-E, N-E), and the medium is ceramic, which is a kind of ceramic capacitors. Y capacitors and high voltage ceramic capacitors are different. Y capacitors are safety capacitors. After failure, they will not cause electric shock and will not endanger personal safety. In this case, why not make the capacity bigger and make the application more extensive?

The capacity of the Y capacitor should be no more than 0.1uF. The Y capacity of the Y capacitor produced by most manufacturers is 4700pF, and the Y2 capacity is 10000pF. As for why there is no Y capacitor with a larger value, the main reasons are:

1. Current production process limitations. Because the Y capacitor is different from the ordinary high-voltage ceramic capacitor, it has to withstand higher pulse voltage, and there is no risk after the capacitor fails. Therefore, the ceramic medium should not be too thin, resulting in a small capacitance.

2. The scope of the application. The Y capacitor is mostly used to suppress the electromagnetic interference of the power supply, so it is often connected between the power line and the ground. The power supply is 50Hz AC in China, and the capacitor has the ability to block DC communication. Therefore, after the power is turned on, there is a certain current passing through the Y capacitor. The larger the capacitance value, the larger the current flowing, the current is called Leakage current.

Now, there is a leakage current requirement in the electrical equipment. The machine operating in the tropics requires that the earth leakage current should not exceed 0.7 mA. When working in a temperate machine, the ground leakage current should not exceed 0.35 mA. Otherwise, there is a hidden danger. The Y capacitor is not required to be too large. I believe that after the advancement of technology, it is possible to produce a large-capacity Y-capacitor. At present, the guarantee is the first, and the capacitors are purchased to find a regular capacitor manufacturer.

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