Test method for lightning protection grounding tester for lightning protection project of Henan school 1. Grounding resistance test requirements: a. AC working grounding, grounding resistance should not exceed 4Ω; b. Safe working grounding, grounding resistance should not exceed 4Ω; c. DC working grounding The grounding resistance should be determined according to the specific requirements of the computer system. 1. Grounding resistance test requirements:
a. AC working ground, the grounding resistance should not exceed 4Ω;
b. Safe working grounding, the grounding resistance should not exceed 4Ω;
c. DC working grounding, grounding resistance should be determined according to the specific requirements of the computer system;
d. The grounding resistance of the lightning protection ground should not exceed 10Ω;
e. For jointed grounding of shielded systems, the grounding resistance should not exceed 1Ω.
Second, the grounding resistance tester
The ZC-8 type grounding resistance tester is suitable for measuring the resistance values ​​of various power systems, electrical equipment, lightning rods and other grounding devices. It is also possible to measure the resistance value of the low-resistance conductor and the soil resistivity.
Third, the instrument work consists of a hand-cranked generator, a current transformer, a sliding wire resistance and a galvanometer. All the mechanisms are housed in a plastic case, and the outer skin is easy to carry. The accessory has an auxiliary probe wire and the like, and is mounted in the accessory bag. Its working principle uses the reference voltage comparison formula.
4. Check if the tester is complete before use. The tester includes the following components.
1. One ZC-8 type grounding resistance tester
2. Two auxiliary grounding rods
3, one wire 5m, 20m, 40m each
Five, use and operation
(1) When measuring the grounding resistance value, the E terminal of the instrument is connected to the 5m wire, the P terminal is connected to the 20m wire, the C terminal is connected to the 40m wire, and the other end of the wire is connected to the grounding electrode EËŠ, potential Probe PËŠ and current probe CËŠ, and EËŠ, PËŠ, CËŠ should be kept straight, with a spacing of 20m
(20) Wiring diagram when measuring less than 1Ω grounding resistance Connect the two E-terminal wires on the instrument to the grounding body to be tested to eliminate the additional error introduced by the connecting wire resistance during measurement.
2, the operation steps
(1) All wiring on the instrument side should be correct.
(2) The instrument wiring should be in firm contact with the grounding pole EËŠ, the potential probe PËŠ and the current probe CËŠ.
(3) After the meter is placed horizontally, adjust the mechanical zero of the galvanometer and return to zero.
(4) Set the “magnification switch†to the maximum magnification and gradually increase the crank speed to 150r/min. When the galvanometer pointer is deflected in a certain direction, turn the dial to return the galvanometer pointer to the "0" point. At this time, the reading on the dial multiplied by the magnification file is the measured resistance value.
(5) If the dial reading is less than 1, the galvanometer pointer is still not balanced. You can set the override switch to the magnification of the first step until it is fully balanced.
(6) If the meter galvanometer pointer is found to be dithered, the crank speed can be changed to eliminate the jitter.
Six, matters needing attention
1. It is forbidden to measure when there is lightning or the object is charged.
2. When carrying and using the instrument, be careful to avoid violent vibration.
Henan school lightning protection project lightning protection grounding tester test method
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Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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