Clamp-on Earth Resistance Tester, 0.010Ω~1000Ω

Resistance Measurement Accuracy

Q1: What is a clamp-on earth resistance tester?
A1: The clamp-on earth resistance tester can measure the connection resistance of any looped system without using an auxiliary ground rod or interrupting the grounding of the equipment under test. As long as the ground wire or ground rod is clamped with the clamp head, the ground resistance can be measured safely and quickly. It can also be applied to multiple parallel grounding systems. The clamp-on ground resistance tester can measure the leakage current of 1MA, and the neutral line current can reach 20A. This function is especially important when the ground network to be tested contains large noise and harmonics.

Q2: How does a clamp ground resistance tester work?
A2: The basic principle of the clamp ground resistance tester to measure the grounding resistance is to measure the loop resistance. The jaw part of the clamp meter consists of a voltage coil and a current coil. The voltage coil provides the excitation signal and induces a potential E on the loop under the test. Under the action of the potential E, a current I will be generated in the circuit under test. The clamp meter measures E and I, and the measured resistance R can be obtained by the following formula. The formula is R=E/I. This is how a clamp-on ground resistance tester works.

Q3: What is the earth resistance tester used for?
A3: The ground resistance tester can accurately measure the grounding impedance, grounding resistance and grounding reactance of large grounding grids.

• It accurately measures the surface potential gradient in the large-scale grounding grid area.
• Earth resistance tester can measure the contact potential difference, contact voltage, step potential difference and step voltage of large grounding grids.
• Measure the transfer potential of large-scale grounding grids and soil resistivity accurately.
• Digital earth resistance tester is used to measure the on-resistance of the grounding down-conductor.

Tips for measuring ground resistance

• When measuring grounding resistance with an AC power supply, an independent power supply, usually a separate transformer, should be used, and the neutral point and grounding point should be open to prevent errors caused by shunting or current failure. The voltage level is estimated based on the current loop impedance and the required current.
• In many substations, the overhead ground wire of the transmission line is connected with the grounding device of the substation, which will affect the measurement results of the grounding resistance of the grounding device of the substation. The lightning conductor of the line is disconnected from the electrical connection of the grounding device of the substation.
• Because a large current needs to be injected into the current pole, it will cause harm to nearby people and animals. Therefore, special personnel must be supervised during the measurement.
• During the test, the current leadership must flow a larger current, therefore, the current loop must have a larger wire cross-section.

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