The Effect of Humidity on Static Electricity Induced Reliability Issues of ICT Equipment in Data Centers-Motivation and Setup of the Study

摘要

Historical evidence suggests that electrostatic discharge (ESD) may cause reliability issues in a data center. Low humidity allows and enhances the accumulation of electrostatic charge on isolated conductors and insulative materials which may increase the risk of ESD induced equipment failures. Besides enhanced charge accumulation and increased ability to retain charges low humidity will also increase the currents during a discharge due to influences on the development of sparks. High humidity may help minimize ESD events and reduce their severity but at a significant increase in the cost of energy consumption as well as other considerations related to changes in the operating environment. This research project under ASHRAE 1499-RP determines the correlation between the risk of equipment failure from ESD at various temperature and humidity levels. The study provides answers to the questions: Will reducing the humidity in data centers significantly increase the risk of ESD related damage or upset errors? Which additional measures need to be implemented to counteract any significant risk increase? Two types of experiments are conducted: In the electrostatic charge accumulation experiments, the voltage levels reached by people operating in lower humidity environments is measured as a function of flooring, footwear, grounding and environmental conditions. This provides a measurement of maximum voltage levels, their distribution functions and dependencies. The second set of experiments investigates the discharge process for given voltages, as humidity will also influence the spark development. Here potentially damaging discharge currents and electromagnetic fields are measured for discharges of humans, but also for sparks that can occur if a charged cable is inserted into a connector. The resulting set of electrical current and electromagnetic field data can then be compared to qualification levels at which typical telecommunication equipment is tested at prior to usage in data centers to estimate the likelihood of upset of damage to the equipment as a function of humidity. The paper describes the motivation and the experimental setup of the study and illustrates the relationships based on preliminary results.