How to Improve the Measurement Accuracy of Ground Resistance

Introduction

Ground resistance is a critical parameter for the safe operation of power systems and various equipment. It refers to the resistance value between the grounding body and the earth, which directly impacts the safety and stability of the equipment. A well-designed grounding system can effectively prevent damage from external disturbances such as lightning overvoltage and electrostatic discharge, while also ensuring personnel safety. Therefore, regularly testing and measuring ground resistance to ensure compliance with relevant standards is of significant practical importance.

Ground Resistance Testing: Important Considerations

Measurement Method Selection: The measurement method should be chosen based on the grounding resistance of the tested body and the required accuracy. For critical projects with relatively low grounding resistance, the current-voltage method is preferred. When using Class 1 to 1.5 measuring instruments, the measurement error can be kept below 5% to 10%. For larger grounding resistances, a ground resistance tester can be utilized.

Distance Requirements: The distance between the tested ground body, current electrode, and voltage electrode must meet specified requirements.

Lead Specifications: The cross-sectional area of the connection wires used for measurement should generally not be less than 1.5 mm², and they should be insulated from the ground. Connections to each electrode must be secure with good contact. To minimize mutual inductance effects between the leads, the distance between them should ideally be greater than 5 meters; if this is difficult, it should be at least 1 meter.

De-energizing Equipment: For grounding systems that frequently carry working current, relevant equipment should be de-energized prior to measurement.

Safety Precautions: During ground resistance measurement, significant voltage drops will occur around the current electrode and grounding body. Therefore, no personnel or animals should be within a radius of 30 to 50 meters to avoid accidents or interference with measurement results.

Soil Moisture Considerations: Since soil moisture has a substantial impact on ground resistance, measurements should not be taken immediately after rainfall.

Repeating Measurements: Ground resistance should be measured multiple times (3 to 4 times), discarding any outlier data, and using the arithmetic mean as the actual result.

Conclusion

In the measurement of ground resistance, adhering to scientific testing methods and precautions is essential. Accurate measurements not only enhance testing reliability but also provide a solid basis for subsequent maintenance of the grounding system. By taking multiple measurements and calculating an average, random errors can be effectively minimized, improving the credibility of the data. In summary, prioritizing the testing and maintenance of ground resistance is vital for ensuring the safe operation of electrical equipment and protecting both personnel and equipment.

JYD Grounding Down Wire Continuity Tester (10A)
Using advanced power supply technology, it is a highly automated portable tester used to measure the on-resistance value between the grounding down-conductors of various power equipment in the substation.

1. The test current is 10A, 5A, 1A three switches.
Vertical chassis structure, integrated design of test line and instrument, easy to carry and convenient
2. The measuring radius is not less than 50 meters under the 10A gear
Field operation
3. The wireless controller remotely controls the instrument test and receives the test data, which is convenient for on-site use
4. The machine has the function of protection and alarm for input mis-connected AC380V power supply, reducing the damage to the instrument caused by mis-operation
5. The test speed is fast, and the resistance data is displayed in about 3 seconds
6. The instrument has a built-in large-capacity lithium battery pack, which has both AC and DC functions. It has a single quick test mode and a continuous test mode, which is convenient for the test site without AC power (optional)

7. The instrument has functions such as perpetual calendar, 100 sets of data storage, Chinese and English interface switching, printing data, etc., and the data will not be lost when it is turned off, which is convenient for reference.

Technical Specification:

Output current	1A, 3A, 5A, 10A
Min. Resolution	0.001 mΩ
Measuring range	0.8 mΩ-0.8 Ω (10A) 1 mΩ-2Ω (5A) 5 mΩ-3Ω (3A) 10 mΩ-10Ω (1A)
Resolution	0.1μΩ
Display	LCD Screen
Storage	1000 recorders
Accuracy	±0.2%+0.002 mΩ
Working temperature	0~40 °C
Working humidity	<90%RH, no condensation
Power supply	Built-in battery, AC 220V±10V,50Hz±1 Hz
Max. power consumption	100W
Size	300 mm*240 mm*140 mm
Weight	Tester :3.8Kg   accessories box :8.5Kg