Several Common Wiring Methods for Ground Resistance Testers - Yangzhou Darui
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Ground resistance tester measurement methods usually include the following: single clamp method, double clamp method, two-wire method, three-wire method, and four-wire method, each with its own characteristics. In actual measurement, try to choose the correct method to ensure accurate results.
1. Single Clamp Measurement
Measure the ground resistance at various points in a multi-point grounding system without disconnecting the ground connections to prevent danger.
Suitable for: multi-point grounding where disconnection is not allowed. Measure the resistance at each connection point.
Wiring: Use a current clamp to monitor the current at the test location.
2. Double Clamp Method
Conditions: multi-point grounding, no auxiliary ground rod. Measure the ground.
Wiring: Connect the current clamp from the ground resistance tester manufacturer to the corresponding socket. Clamp both clamps onto the ground conductor, with a distance greater than 0.25 meters between the two clamps.
3. Two-Wire Method
Conditions: There must be a known good ground, such as PEN. The measured result is the sum of the resistance of the tested ground and the known ground. If the known ground resistance is much smaller than the tested ground resistance, the measurement result can be used as the resistance of the tested ground.
Suitable for: areas with buildings and concrete floors, where ground rods cannot be driven due to sealing.
Wiring: e+es receives the tested ground. h+s receives the known ground.
4. Three-Wire Method
Conditions: Two ground rods are required: an auxiliary ground and a detection electrode. The distance between each ground electrode should be no less than 20 meters.
Principle: Apply current between the auxiliary ground and the tested ground. Measure the voltage drop between the tested ground and the probe electrode. The measurement result includes the resistance of the measuring cable itself.
Suitable for: ground grounding, construction site grounding, and lightning rod grounding, QPZ grounding.
Wiring: s connects to the detection electrode. h connects to the auxiliary ground. e and es are connected together and then to the tested ground.
5. Four-Wire Method
Basically the same as the three-wire method, but when used instead of the three-wire method, it eliminates the influence of the measuring cable resistance on low ground resistance measurement results. During measurement, e and es must be directly connected to the tested ground separately. This is very accurate among all ground resistance measurement methods.
Note: The above information and technical parameters are compiled and released by Yangzhou Darui Electric Co., Ltd.
