Resistance measurement of anti-static work surface, floor, chair and wrist strap
A1 Measurement preparation
The object to be measured and the electrodes used for measurement must be clean. Before measurement, they should be cleaned twice with a volatile detergent. After cleaning, wipe the surface with a clean low-cotton cloth and air-dry for at least 15 minutes to make the surface dry and clean.
A2 Test instrument requirements
The resistance value measured by the instrument must be at least 10 times higher and 10 times lower than the resistance value to be measured. When the resistance value to be measured is less than 1×105Ω, the instrument should be able to provide an open-circuit DC voltage of 10V±1V. When the resistance value to be measured is in the range of 1X 10(5)Ω-1×10(11)Ω, it should be able to provide an open-circuit DC voltage of 100V±10V. The other two measuring wires should be relatively insulated.
A3 Electrode Requirements
Each cylindrical electrode weighs 2.5 kg ± 0.5 kg and has a diameter of 63.5 mm ± 2.5 mm. Each electrode has a contact made of electrically conductive material with a Shore A hardness of 50 to 70 (International Rubber Hardness Scale).
A4 Measurement Method
A4.1 Resistance to ground measurement measures the resistance between a point on a surface and a ground connection point or electrostatic grounding device.
A4.2 Surface resistance measurement measures the resistance between two points on a surface.
A4.3 First, mark one or more measurement locations on the object to be measured for the electrodes. These locations represent the points on the surface that are grounded during use.
A4.4 Place the electrodes at the marked measurement locations, adjust the test instrument to the appropriate output voltage, and measure and record the resistance value after 30 seconds of power application.
A4.5 The ambient temperature and humidity must be recorded for all measurements.
A4.6 Resistance to ground measurement after the work surface is installed is shown in Figure A1. See Figure A2 for surface resistance measurement.
A4.7 After floor installation, see Figure A3 for ground resistance measurement. See Figure A4 for surface resistance measurement. Each computer room floor must be measured for ground resistance and surface resistance at least five times, with five randomly selected points measured each time.
A4.8 Chair ground resistance measurement, see Figure A5. Surface resistance measurement, see Figure A6. For chair ground resistance measurement, a thin conductive sheet of material should be used as the floor contact point. Its volume resistivity should be less than 500 n·cm, its Shore A hardness should be between 50 and 70, and its contact area should be no less than 254 mm x 254 mm. The chair's wheels or legs should be placed on this sheet.
Note: When the electrode must be supported by the operator or by conductive material, the outer non-contact surface of the electrode used for measurement on the chair back should be covered with insulating material.
A4.9 Wristband ground resistance measurement, see Figure A7. The measuring instrument used is required to have a visible or audible display signal for the measured resistance value. The electrical connection of the wrist strap is achieved by using a suitable connector for the plug and a rust-free iron hand contact plate with a size of at least 25.4mmX25.4mm. The operator wears the wrist strap and inserts the free end into the test instrument. The hand contact plate must be pressed until the device generates induction.