Dependence of ESD charge voltage on humidity in data centers: Part I - Test methods

The effect of absolute and relative humidity on the charge generated in the human body during different human activities was investigated. Environmental conditions were varied between a relative humidity of 8% to 45% in a temperature range of 5°C to 38°C (41°F to 100.4°F); additionally, a wide range of footwear and flooring types were considered. The human activities studied included well-defined walking, random walking and scraping feet, taking off a sweater and dropping it, and standing up from a chair. The first part of this three-part paper mainly describes the test and data analysis methodology. One conclusion based on the voltages generated across different footwear and flooring combinations is that charge generation depends on the particular activity and associated materials. However, low relative humidity and a low, but not very low, dew point in general produce conditions favorable for high-voltage generation. Of all of the experiments performed, standing up from a chair yielded the highest body voltage. Two other parts of the three-part paper present a detailed analysis.