Excellent performance city electricity over-voltage protection circuit

Published:2011/5/18 3:13:00 Author:TaoXi | Keyword: Excellent performance, city electricity, over-voltage protection | From:SeekIC

The circuit is as shown, this circuit uses the capacitance step-down and simple manostat circuit, when the power supply voltage is normal, the TL431C control pole voltage is less than 2.5V, TL431C circuit is not conduction, the relay contact point is not close. When the city electricity voltage is 250V, the rectifier & filtering current is 3.3mA, the voltage drop of R3 is 11V and the voltage drop of the diode and regulator tube (including the glowing tube) are 26V and 37V. The voltage is separated by R1 and R2, point A's voltage is 2.55V, the TL431C circuit is conduction, and relay K closes, the city electricity becomes the short-circuit to make the power supply current flowing device tripping or the fuse fusing, so this circuit protects the household appliances.



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