Indirect discharge test of electrostatic discharge generator
According to the standard, the indirect discharge test in contact discharge should be carried out when the electrostatic discharge generator discharges. Specifically, a horizontal coupling board is laid on the test table, and a vertical coupling board is set on the side at the same time. Then discharge the horizontal and vertical coupling board with the electrostatic gun to see whether the equipment is affected or not.
According to the standard, both the horizontal and vertical coupling plates are grounded by two 470K resistances, and the two resistances are distributed at both ends of the grounding wire, which leads to the following problem:
1. What's the function of the two resistors?
2. Why use 2 470K resistors?
3. Why are the two resistors at both ends of the ground wire?
As you may know, the first problem is that the discharge of the horizontal and vertical coupled plates affects the equipment through transient electromagnetic fields and static electric fields. Therefore, the two resistances are designed to prevent the rapid discharge of static charges along the ground, and the electrostatic field cannot be generated.In addition, high impedances tend to accumulate charges, which eventually accumulate until these resistances are released.
The second problem is that the resistance of the human body to the ground is about 1M, and the resistance of the two 470K is exactly the same.
The third problem is to put the two resistances on opposite ends. Because the impedance does not match, the current generated by the static charge bounces back and forth between the two resistances until it disappears, reducing the current flowing to the ground.
This test is mainly to simulate the discharge of human body to other objects at the side of the tested equipment, and indirectly to test whether the tested equipment is affected.