1. Surface resistance detection:
(1) Test equipment:
Digital Megohm table: The detection voltage is 100∨, the measuring range is 1.0 × 105 ~ 1.0 × 1012 ohms, the accuracy level should not be lower than 2.5 level; standard electrodes: 2 pieces, copper, surface chrome-plated, cylindrical, diameter 63.5 mm, weight 2270 g; and used in conjunction with a megger, it is used to test the surface resistance of anti-static ground, using conductive rubber as the electrode (volume resistance <1.0 × 103 ohms).
(2) Environmental requirements: The test should be carried out as much as possible in an environment with a temperature of 23 ± 8 ℃ and humidity of 50 ± 5% (keep this environment for 24 hours).
(3) Test method:
Before acceptance measurement of anti-static epoxy floor, clean the surface with clean gauze. Wipe itand clean it with neutral liquid if it is seriously stained. Then turn on the indoor air conditioner and let it run at a certain temperature for 2-3 days, and measure under the specified temperature and humidity conditions. Before placing the electrode, use a strip of soft cloth to remove any dust on the floor surface. Before placing the electrode surface, use a strip of clean, soft cloth with isopropyl alcohol and at least 70% water, insert it clean and allow it to dry. . Connect the positive electrode of the megger to the ground, place the negative electrode on the ground surface and take a reading for 5 seconds after applying voltage or after the number is stable. The electrode should be located approximately 30 mm from the edge and. the distance between the two electrodes must not be less than 900 mm. Among them, at least 5 tests must be carried out for each surface area of 46.5 m2. At least 3 dThe 5 tests should include areas subject to wear, chemical or water splashes and visibly contaminated areas.
2. System resistance detection:
(1) Detection equipment:
< p>Digital megoohmmeter: detection voltage is of 100∨, the measuring range is 1.0×105～1.0×1012 ohms, the accuracy degree should not be less than 2.5. Standard electrode: 1, copper, chrome-plated surface, cylindrical shape; , diameter It measures 63.5 mm and weighs 2,270 g. It is used in conjunction with a megger to test the surface resistance of antistatic floors. Conductive rubber is used as the electrode (volume resistance <1.0 × 103 ohms).
(2) Environmental requirements: The test should be carried out as much as possible in an environment with a temperature of 23 ± 8 ℃ and humidity of 50 ± 5% (keep this environment for 24 hours).
Method oftest:
Before acceptance measurement of antistatic epoxy floor, clean the surface with seriously contaminated clean gauze. the parts should be cleaned with neutral liquid, then turn on the indoor air conditioner, keep it running at a certain temperature for 2-3 days, and measure under the specified temperature and humidity conditions. Before placing the electrode, use a strip of soft cloth to remove all dust from the floor surface. Before placing the electrode, use a strip of clean, soft cloth to cover the electrode surface with isopropyl alcohol and at least 70% water. test dry.Clean and dry. Connect the positive electrode of the megger to the ground, place the negative electrode on the ground surface and take a reading for 5 seconds after applying voltage or after the number is stable. The electrode should be located approximately 30 mm from the edge and. the distance between the two electrodes does notmust not be less than 900 mm. Among them, at least 5 tests must be carried out for each surface area of 46.5 m2. At least 3 of the 5 tests must include areas subject to wear, chemical or water splashes, and visibly contaminated areas.
In summary, the following factors should be considered when detecting surface resistance and system resistance:
< p>A. Influence of temperature and humidity
As temperature and humidity increase, the measured dielectric strength value of antistatic epoxy flooring decreases; surface resistance is sensitive to humidity, while volume resistance is; more sensitive to temperature. As the ambient temperature increases, the surface of the anti-static epoxy floor will be easily adsorbed and form a water film, which will increase surface leakage. If the material is hygroscopic, this increaseswill also significantly reduce the body's conductance current. As the temperature increases, the adsorption current and conductive current of the soil dielectric material will increase accordingly. For example, the resistance value of dielectric materials at 70°C is only 1/10 of the resistance value at 20°C. If the relative humidity increases by 10%, the resistance value of grounded dielectric materials that easily absorb moisture will be reduced. by about an order of magnitude.
The effect of humidity on surface resistance is shown in Figure 1:
B. Effect of shape, size and electrode. weight
From a theoretical and practical point of view, the contact area of the electrode is large and the weight is heavy, and the measured resistance value is small. small and the weight is light and the measured resistance value is high. The main function of epoxy floor projectAntistatic is to ensure the elimination of static electricity on the human body. Therefore, the size and weight of the electrodes should simulate the size of shoes, feet and the weight of the human body.
C. Influence of test voltage and reading time
The resistance value of antistatic epoxy floor depends on the test voltage The size and the time during which the voltage is applied vary. Generally at room temperature, when the voltage is low, the conductivity current increases linearly with the applied voltage. When the voltage exceeds a certain value, due to increased dissociation and intensified ionization activity, the current increases much faster than the voltage. increase. The higher the test voltage, the lower the measured resistance value.
When the normal test voltage of anti-static epoxy dielectric material reachesrelatively stable reading time, the reading time recommended above may not be sufficient for systems with high resistance (approximately > 1010Ω). For systems with low resistance (<106Ω), the reading time of 5 seconds is more than sufficient. In order to consider that the data reading time should not be too long, otherwise the field test will take too many points, which will take too long and the work efficiency will be low. The time is too short, the operation takes too long, and the instrument also has a response time.
If a second measurement is necessary after the measurement, the electrodes must be short-circuited to release the charged charges and polarized charges on the electrodes before starting. Next measurement. The duration of the short circuit depends on the ground material and the value of the applied voltage. But generally it is advisable to short-circuit for at least 1 minute.
3. System earth resistance detection:
(1) Detection equipment:
Earth resistance meter: specifications 0~1~10~100 ohms, using three-pole method to measure earth resistance. Megohmmeter, also known as megohmmeter, is composed of a high voltage hand generator and a double moving magnetoelectric coil current ratio meter. It has stable output voltage, accurate readings, low noise, light shaking and is equipped with a shield. to avoid leakage current of measuring circuit devices and separate binding terminals.
(2) Detection method:
As shown in Figure 2, disconnect E1 from the grounding system earth
1. Keep the potential detection pin P1 and the current detection pin C1 acm away from each other in a straight line along the ground electrode E1 to be measured, and the bPotential detection rock P1 is inserted. between the ground electrode E1 and the current detection pin C1.
2. Use wires to connect E1, P1 and C1 to the corresponding terminal buttons on the meter.
3. Place the meter in a horizontal position and check if the galvanic needle is pointing toward the center line. Otherwise, use the zero adjuster to adjust it to point toward the center line. .
4. Set the “magnification scale” to the maximum multiple, slowly turn the motor crank and at the same time turn the “measuring dial” to get the galvanic needle pointer on the center line.
5. When the galvanometer needle is close to equilibrium, increase the speed of the generator crank to over 120 revolutions per minute and adjust the "measuring dial". Keep the pointer on the center line.
6. If the reading of the “measuring dial”is less than 1, the "Magnification Scale" should be set to a smaller multiple of the scale, then the "Measuring Scale" should be readjusted. Dial" to get the correct reading.
7. Multiply the “Measuring Dial” reading by the multiple of the “Magnifying Dial” to obtain the measured earth resistance value.