How does the surface resistance tester measure static electricity?
The main application range of the surface resistivity tester: high-resistance testing of materials such as anti-static products (anti-static shoes, anti-static plastic rubber products, anti-static raised floors in computer rooms, etc.) resistance value detection; Material volume resistivity (rate) and surface resistivity (rate) measurement; electrochemistry and material testing, as well as physics, optics and materials research; weak current measurement such as photoelectric effect and device dark current measurement.
The working principle of the volume resistivity tester: According to Ohm's law, the measured resistance Rx is equal to the applied voltage V divided by the passing current I. The working principle of the traditional high resistance meter is that the measuring voltage V is fixed, and the resistance value is obtained by measuring the current I flowing through the sampling resistor. It can be seen from Ohm’s law that since the current I is inversely proportional to the resistance, not directly proportional, the displayed value of the resistance is non-linear, that is, when the resistance is infinite, the current is zero, that is, the zero position of the meter is ∞. The nearby scale is very dense and the resolution is very low. The entire scale is non-linear. In addition, when measuring different resistances, the voltage V will also change somewhat, so ordinary high resistance meters have poor accuracy and low resolution.
Preparation for insulation resistance test:
1. Before the test, the power supply of the tested equipment and all external connections should be removed, and the tested object should be short-circuited and grounded for 1 min. The larger capacitance should be discharged for at least 2 min to avoid electric shock and affect the measurement results.
2. Check whether the pointer of the meter is at infinity, otherwise the mechanical zero adjustment screw needs to be adjusted. Note: When adjusting the mechanical zero adjustment screw, the left and right adjustment amount is half a turn.
3. Wipe off the dirt on the surface of the test object with a dry and clean soft cloth. If necessary, clean the dirt on the surface of the casing with gasoline to eliminate the influence of surface leakage current on the test results.
4. Insert one end of the high-voltage test line (red) into the LINE end, and connect the other end to or use a hook to hang on the high-voltage conductor of the tested equipment, insert one end of the green test line into the GUARD end, and connect the other end to the high-voltage protection of the tested equipment. In order to eliminate the effect of surface leakage current, insert another black test wire into the EARTH end, and connect the other end to the shell or ground of the device under test.
Note: When wiring, pay special attention to the connection of LINE (red) and GUARD (green), and do not short-circuit them.
Insulating material voltage breakdown tester/insulating material dielectric strength tester is suitable for continuous and uniform boost or stepwise boost, applying AC/or DC voltage to the sample until breakdown, measuring the breakdown voltage value, and calculating The breakdown strength of the sample: Use a rapid boost method to increase the voltage to the specified value, and keep the sample for a certain period of time without breakdown. Set the specified value at this time to the withstand voltage value of the sample. The thin-film plastic power frequency dielectric electric strength tester can automatically distinguish the breakdown of the sample and collect breakdown voltage data and leakage current. At the same time, it can automatically return to zero when the voltage is rapidly reduced at the moment of breakdown. In other words, the polyethylene dielectric constant tester, in order to avoid the risk of purchase, it is recommended that you must confirm the supplier's qualifications and product quality before purchasing the product.
Since the volume resistance is always more or less included in the surface resistance test, the surface resistance is measured approximately, and the measured surface resistance value mainly reflects the degree of surface contamination of the tested sample. Therefore, the surface resistivity It is not a parameter of the characteristics of the surface material itself, but a parameter related to the characteristics of the surface pollution of the material. How to operate and use a regular anti-static surface resistance tester more safely.