EMC Education

This is Part2 of a three-part paper investigating the dependence of charge voltage generated by
human activity on humidity in data centers. The first paper described the experimental methods, while
this paper is devoted to the analysis of the electrostatic charge voltage levels along the following
parameters: relative humidity, absolute humidity, footwear, flooring, and type of activity. The human
activities studied included well-defined walking, random walking, taking off and dropping a sweater,
and standing up from a chair. This study confirms the importance of footwear and flooring and
quantifies their effectiveness. The results indicate that lower absolute humidity may not always lead to
higher voltages, while reducing the relative humidity will cause the average voltages to increase. The
high voltages created by removing and dropping a sweater and by standing up from a chair indicate
that these types of user activities might pose a higher risk of generating voltages greater than 6 kV
much larger than the walking activities. The analyses are based on the definition of walking, standing,
chair event and sweater event voltages, as presented in Part1.

This paper is the third paper of a series that investigates the ESD-related voltages and risks in data
center. This paper analyses the risk of damage or upset under the following environmental conditions
. The main purpose of this study is to evaluate the
increase of ESD related upsets or failures caused by reducing the relative humidity from 25% to 8%. The
pattern-walking test, random walking test and the extrapolation method described in (Moradian 2014) are
also used in this paper. As the distribution function of the tribocharging induced voltage is not directly
k ow he hebyshev’s I equ li y is use o predict the upper bound for the probability of ESD-related
failures.