>During a quality inspection in my lab the inspector >I've got a non-conformity due to the lack of resistivity check on the >470 Kohm resistor employed to connect the reference plane of the ESD table >to the ground. >This is required according to EN 61000-4-2 >Could anyone give me some hints in order to understand the influence of that >resistor on the ESD test ?
The HCP is connected to ground via the 470k resistors (one at each end of the cable) both for safety considerations (same idea as the 1 Megohm resistance in most ESD wriststraps), and also to serve as a drain path for charge that builds up during the process of testing. Without the drain, the HCP surface would eventually charge to the point where discharges to the gun would not occur. The identical resistance values connecting the VCP (Vertical Coupling Plane) to ground are required for the same reasons. It is a good idea to check the resistance path fairly often using an ohmmeter since the connections typically are subject to quite a bit of mechanical movement. --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
