The hybrid coupler company methods are usually as follows: two wire method, three wire method, four wire method, single clamp method, and two clamp method. Each has its own characteristics, the actual measurement, as far as possible to choose the correct way, in order to make the measurement results accurate.
1. Two-wire method
Conditions: There must be a known well grounded ground, such as PEN, etc., where the measured result is the sum of the resistance of the measured ground and the known ground. If the earth is known to be much less than the resistance of the earth under survey, the result of the measurement can be taken as the result of the earth under survey.
Suitable for: buildings dense or cement ground seal can not hit the pile area.
Wiring: E+ES to the measured place, H+S to the known place.
2. Three-line method
Condition: There must be two ground rods: one auxiliary and one probe electrode.
The distance between each ground electrode is not less than 20 meters.
The idea is to add an electric current between the auxiliary ground and the earth being measured,
Measure the voltage drop between the earth being measured and the probe electrode, including the resistance of the cable itself.
Applicable to: ground grounding, construction site grounding and lightning protection grounding.
Connection: S is connected to the probe electrode, H is connected to the auxiliary ground, E and ES are connected to the measured ground.
3. Four-wire method
Basically the same as the three-wire method, it replaces the three-wire method when the hybrid coupler company is low and the influence of the measurement cable resistance on the measurement results is eliminated. During the measurement, E and ES must be directly connected to the measured ground separately. This method is the most accurate of all the hybrid coupler company methods.
4. Single forceps measurement
Measure the ground resistance of each ground point in the multipoint grounding. Do not disconnect the ground connection to prevent danger.
Suitable for: multi-point grounding, cannot be disconnected, measure the resistance of each ground point.
Wiring: Use current clamp to monitor the current at the ground point under test.
5. Double Clamp Method
Conditions: multi-point grounding, no auxiliary ground pile, single grounding measurement.
Wiring: Use the current pliers specified by the manufacturer to connect to the corresponding jack, clamp the two pliers on the ground conductor, the distance between the two pliers should be greater than 0.25m.
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