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The importance of LED display power supply grounding
by：Demo
2021-07-14
The main components of the LED display are LEDs and drive chips, which belong to a collection of microelectronic products. The working voltage of the LED is about 5V, and the general working current is less than 20 mA. Its working characteristics determine its resistance to static electricity and abnormal voltage or current impact. This requires us to recognize this point in the production and use process and pay enough attention to take measures to protect the led display. The power grounding is the most commonly used protection method for LED displays.
Why should the power supply be grounded? This is related to the working mode of the switching power supply. Our LED display switching power supply is a series of methods such as filtering-rectification-pulse modulation-output rectification-filtering and other means to convert alternating current (AC) 220V city power into direct current (DC) 5V direct current A device with stable power output.
In order to ensure the stability of the AC/DC conversion of the power supply, the power supply manufacturer connects an EMI filter circuit from the live wire to the ground wire in the circuit design of the AC220V input terminal in accordance with the national 3C mandatory standard. In order to ensure the stability of AC220V input, all power supplies will have filter leakage when working, and the leakage current of a single power supply is about 3.5mA. The leakage voltage is about 110V. When the display is not grounded, the leakage current may not only damage the chip or burn out the lamp. If more than 20 power supplies are used, the accumulated leakage current can reach more than 70mA.
It is enough to cause the leakage protector to act and cut off the power supply. This is also the reason why our display cannot use the leakage protector. If the leakage protection is not connected and the display is not grounded, the leakage current superimposed by the power supply will exceed the safety current of the human body, and the voltage of 110V is enough to cause death! After grounding, the voltage of the power supply shell is close to 0 to the human body. It shows that there is no potential difference between the power supply and the human body, and the leakage current is led to the ground. Therefore, the LED display must be grounded.
Why should the power supply be grounded? This is related to the working mode of the switching power supply. Our LED display switching power supply is a series of methods such as filtering-rectification-pulse modulation-output rectification-filtering and other means to convert alternating current (AC) 220V city power into direct current (DC) 5V direct current A device with stable power output.
In order to ensure the stability of the AC/DC conversion of the power supply, the power supply manufacturer connects an EMI filter circuit from the live wire to the ground wire in the circuit design of the AC220V input terminal in accordance with the national 3C mandatory standard. In order to ensure the stability of AC220V input, all power supplies will have filter leakage when working, and the leakage current of a single power supply is about 3.5mA. The leakage voltage is about 110V. When the display is not grounded, the leakage current may not only damage the chip or burn out the lamp. If more than 20 power supplies are used, the accumulated leakage current can reach more than 70mA.
It is enough to cause the leakage protector to act and cut off the power supply. This is also the reason why our display cannot use the leakage protector. If the leakage protection is not connected and the display is not grounded, the leakage current superimposed by the power supply will exceed the safety current of the human body, and the voltage of 110V is enough to cause death! After grounding, the voltage of the power supply shell is close to 0 to the human body. It shows that there is no potential difference between the power supply and the human body, and the leakage current is led to the ground. Therefore, the LED display must be grounded.
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