NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
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NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
Author: Noyafa–Cable Locator Suppliers
Grounding resistance measurement method and specification requirements grounding resistance What is grounding and grounding resistance? When the power frequency current or impulse current flows from the grounding electrode to the surrounding ground, the resistance presented by the soil is called grounding resistance. One or a group of conductors that are in close contact with the ground and form an electrical connection is called a ground electrode.
It is connected to the earth through the grounding electrode, which is called grounding. Grounding, divided by use: lightning protection grounding, anti-electrostatic grounding, working grounding, neutral grounding and logic grounding. The standard specification of grounding resistance requires: lightning protection is less than or equal to 10 ohms, AC work should be less than or equal to 4 ohms, DC work should be less than or equal to 4 ohms; anti-static is less than or equal to 100 ohms.
The common ground body (joint ground body) is not more than 1 ohm. Grounding resistance measurement method: two-wire method: there must be a known good grounding ground, such as PEN, etc. The measured result is the resistance sum of the measured ground and the known ground. If it is known that the resistance of the ground is much smaller than the measured ground, the measurement result can be used as the result of the measured ground.
Three-wire method: There are two ground rods: an auxiliary ground and a detection electrode. The interval between each ground electrode is not less than 20 meters. The principle is to add current between the auxiliary ground and the measured ground, measure the voltage drop between the measured ground and the detection electrode, and the measurement result includes the resistance of the measurement cable itself.
Four-wire method: equivalent to the three-wire method, replacing the three-wire method when measuring low ground resistance and eliminating the influence of the measurement cable resistance on the measurement results. When measuring, E and ES should be directly connected to the measured ground separately. A single clamp measurement measures the ground resistance of each ground point in a multi-point ground, and the ground connection cannot be disconnected to prevent a hazard.
Double clamp method: multi-point grounding, no auxiliary ground piles, single grounding measurement. The measurement method and specification of grounding resistance require grounding resistance Shenzhen Noyafa Electronic Technology Co., Ltd.
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