Measurement Principle of Dual-Clamp Method
Dual-Clamp Ground Resistance Tester method has the following advantages: First, it is simple to operate. It can be tested without disconnecting the power supply of the equipment under test, while it is in normal operation, without inserting a measurement probe or separating the electrode under test. Only two clamps are needed to clamp the grounding conductor to measure its grounding resistance. Second, it has high accuracy. Its accuracy can reach 0.01Ω. Third, it has strong anti-interference capability. It can filter out various power frequency harmonics. Fourth, it can be used as a supplement to the earth stake method. In many conditions (such as densely built areas or areas covered with cement), it is difficult or even impossible to use the stake method to measure grounding resistance. Using the dual-clamp measurement principle, it is possible to measure without driving ground stakes. The only disadvantage of this measurement principle is that it cannot directly measure single-point grounding systems. In single-point grounding systems, the clamp ground resistance meter should be used with caution.
The measurement principle is briefly described as follows: This instrument is equipped with two clamps: a voltage clamp and a current clamp.
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