Customer Problems:
The customer is that testing equipment room of the electric power industry, and then there is static electricity carried by the person, and now entering the testing equipment room to touch the machine will generate static electricity.
Before solving the problem, let's understand how static charges are created?
The motion between two surfaces generates an electric charge, and at least one of the surfaces has a high current resistance. The generated charge remains until it can be dissipated by current or discharge.
For example, as a person moves across the floor, they build up a negative charge that increases with the number of times the person moves.
The process by which a person builds an electrical charge is called friction charge. This resulting charge is called electrostatic charge.
If the stored electrostatic charge is large enough, when a charged object approaches a conductive or grounded object, the excess charge will flow between the two objects and be neutralized. This phenomenon is an electrostatic discharge and may produce visible sparks.
If the charged object is a person, that person will experience a mild electrostatic shock. However, if the electrostatic discharge passes through a piece of sensitive electronic equipment, irreversible damage may result.
The picture shows the movement of the human body to electrostatic accumulation and then to electrostatic discharge
Conditions at the customer's site:Anti-static flooring already in place
Solution:
1. It is vital that site personnel wear appropriate clothing and anti-static shoes to minimize the build-up of static charges within personnel that can be safely discharged by grounding.
2. In order to ensure the reliability of the connection between the human body and the floor, we need to measure the integrated resistance of the human body through the instrument, which is recommended to be installed at the entrance of the testing room, to accurately test whether the resistance of the human body through the hand-wristband and shoes grounding is qualified or not, to keep away from static electricity injuries, and to make your working environment safer and more reliable!
3. We need to verify the effectiveness of the anti-static flooring.
You can refer to the standard “General Specification for Anti-static Movable Floor” GB/T 26340-2018 or SJ/T 10694-2006 “General Specification for Anti-static Testing of Electronic Product Manufacturing and Application Systems” to measure the anti-static performance of surface resistance and system resistance. The qualified index for point-to-point resistance test of the surface is 1×10^4 ~ 1×10^9 ohm, and the qualified index for system resistance test is 1×10^4 ~ 1×10^9 ohm.
4. Confirmation of the effect of static electricity after improvement (personnel walking voltage test)
To effectively control personnel voltages, flooring materials must be used in conjunction with antistatic footwear.The ANSI-ESD STM97.2 standard defines a test method for measuring the accumulation of voltages from personnel in combination with footwear and flooring materials. The test method provides data related to user-specific environments, applications, and controlled laboratory conditions. A common source of static voltage for people in the work environment is the separation of the foot from the floor when walking. By choosing the right shoe/floor system, the effects of static charge generation and accumulation can be minimized.
