Electrostatically induced voltage on conductive objects contained in metal box when charged body moves away from the box

Electrostatically induced voltage generated on printed circuit boards in a grounded metal box occasionally causes a malfunction and failure of the electronic equipment. A person who walks into a room that has an air conditioner can be electrified up to -10 kV or more. However, a microelectronics device malfunctions by an occurrence of induced voltage of less than 10 V. In the present paper, the induced voltages on an ungrounded one of two conductors that are contained in the metal box are measured and calculated when a charged body moves away from a partially opened metal box. The induced voltages are measured by the use of a spark gap and an electromagnetic wave sensor and are compared with the results from an electrostatic voltmeter. The induced voltages are calculated, moreover, by the use of q=cv, with the capacitances and charges. The results show that the induced voltages of -42% of the voltages of the charged body are generated in the metal box when a charged body moves away from the metal box. The results will be helpful in considering preventive measures of the malfunction and failure of electronic equipment.