Earth Resistance: Earth resistance refers to the resistance encountered when current flows from the grounding device into the earth and then propagates to another grounding body or dissipates into the distance. The unit of measurement is Ω (ohm). The magnitude of ground resistance reflects the degree of contact between the electrical installation and the earth, as well as the scale of the grounding grid.

Insulation Resistance: Insulation resistance is the most fundamental insulation indicator for electrical equipment and circuits. For handover tests of low-voltage electrical installations, the insulation resistance of motors, power distribution equipment, and power distribution lines at room temperature should not be less than 0.5 MΩ (for operating equipment and wiring, the insulation resistance should not be less than 1 MΩ/kV). The insulation resistance of low-voltage electrical appliances, their connecting cables, and secondary circuits should generally not be lower than 1 MΩ; in relatively humid environments, it should not be lower than 0.5 MΩ; for small circuits and small busbars, the insulation resistance should not be lower than 10 MΩ. The insulation resistance of Class I handheld power tools should not be less than 2 MΩ.

A smaller ground resistance ensures that unsafe currents, such as fault currents or leakage currents, are effectively diverted into the earth, thereby ensuring personal safety. A higher insulation resistance makes it less likely for electrical equipment to be breached by high voltage, ensuring the safe operation and functionality of the equipment. Therefore, ground resistance should be as small as possible, while insulation resistance should be as large as possible.

The ETCR EM3500 High-Voltage Insulation Resistance Tester is a meticulously developed high-performance instrument designed for testing high-voltage insulation resistance. It features comprehensive insulation resistance testing capabilities, user-defined test voltage settings, and excellent anti-interference performance. It excels in environments with strong induced electricity, such as substations, and in scenarios with large distributed capacitance. The instrument is equipped with a full-color touchscreen that displays all test data and battery status simultaneously for clear visibility. The combination of a rotary switch and buttons ensures simple operation. Users do not need to memorize complex procedures—clicking the "HELP" button on the screen will pop up operational guidance, effectively assisting users in operating the instrument. This product is suitable for insulation resistance testing of large-capacity, high-voltage, and strong induced electricity environments, such as electrical equipment and transmission lines. It is an essential tool commonly used in power, telecommunications, meteorology, data centers, oil fields, electromechanical installation and maintenance, and power supply departments of industrial and mining enterprises.

The ETCR EM3200C Dual-Clamp Multi-Function Ground Resistance Tester is a high-end instrument specifically designed for on-site measurement of ground resistance, DC resistance, soil resistivity, ground current, and ground voltage. It incorporates advanced digital processing technology and offers various measurement methods, including the two-wire, three-wire, four-wire, selective, and dual-clamp methods. The instrument utilizes FFT (Fast Fourier Transform) technology and AFC (Automatic Frequency Control) technology, providing unique anti-interference capabilities and environmental adaptability. It ensures strong consistency in repeated tests, guaranteeing high precision, stability, and reliability. With its large-diameter current clamp design, the instrument meets the testing needs of various scenarios. It can measure ground resistance values of large-scale grounding down conductors and flexibly measure ground resistance values of single-point and mesh grounding structures. When measuring parallel grounding systems, it does not require disconnecting any parallel grounding electrodes, significantly improving measurement convenience and providing a perfect solution for grounding performance testing.

ETCR specializes in the research and production of high-voltage insulation resistance testers. It is the manufacturer of the EM3500/EM3520 5kV High-Voltage Insulation Resistance Tester, EM3500B/EM3520B 10kV High-Voltage Insulation Resistance Tester, ETCR EM3520C 15kV High-Voltage Insulation Resistance Tester, and ETCR EM3580 Online Insulation Resistance Tester. For more information, please contact the ETCR service hotline: +86 13802922567 or visit the ETCR official website: www.etcrmeter.com.