Why is “grounding” emphasized everywhere in the power system? What exactly is it used for? Today, let’s talk about this seemingly simple but crucial link, as well as the indispensable “grounding resistance meter” behind it.
Grounding Resistance: Invisible Guardian
Simply put, grounding resistance refers to the total resistance along the path of current returning to the power source through the earth. It is like a “firewall” for the safe operation of electrical equipment, which can effectively prevent overvoltage caused by lightning strikes, short circuits, and other faults from causing harm to equipment and personnel. A lower grounding resistance means that fault current can flow more smoothly to the ground, triggering protective devices faster and reducing harm.
What are the factors that affect grounding resistance?
Soil resistivity: This is the most important factor. The moisture content, salt content, temperature, and soil properties (such as sand and clay) of soil directly affect its electrical resistivity.
The shape and size of the grounding body: The depth, length, cross-sectional area, and number of grounding electrodes of the grounding body will affect the total grounding resistance.
Distance between grounding bodies: When multiple grounding bodies are used, their distances will also affect each other, and being too close will reduce the effect.
Seasonal changes: Soil moisture will vary with the seasons, which in turn affects grounding resistance.
What tools can help us measure?
When it comes to measurement, professional tools are indispensable. The grounding resistance meter is our protagonist today. It can accurately read the total resistance value of the grounding system through certain measurement principles. There are many excellent grounding resistance meters on the market, such as the high-performance instrument launched by HV Hipot Electric Co., Ltd., which can provide accurate and reliable measurement results and is a powerful assistant for power inspection and maintenance.
How to measure and improve grounding resistance effectively?
Regular measurement: The grounding resistance is not constant and needs to be measured regularly, especially before and after seasonal changes.
Choose the appropriate measurement method: Choose single point grounding resistance measurement or overall grounding grid resistance measurement according to the actual situation.
Analysis of measurement results: If the measured value does not meet the standard requirements, it is necessary to conduct a thorough analysis of possible reasons.
Take improvement measures:
Increase the number or size of grounding bodies.
Reduce the burial depth of the grounding body.
Improve soil resistivity, such as adding resistance reducing agents around grounding bodies.
We use the professional equipment provided by HV Hipot Electric Co., Ltd. for precise measurement and evaluation, and their technology in this area is very mature.
Improve the measurement accuracy of grounding resistance
It is crucial to choose a high-performance grounding resistance meter to ensure measurement accuracy. HV Hipot Electric Co., Ltd. has a deep accumulation in the field of power testing equipment. Their high-precision grounding resistance meter can effectively cope with various complex on-site environments and ensure the reliability of grounding resistance measurement.
FAQ
Q1: How does the grounding resistance meter work? A1: The grounding resistance meter usually uses principles such as constant current extrapolation or voltage drop method to calculate the grounding resistance by applying a certain current to the grounding body and measuring the voltage drop when the current flows through the grounding body and the ground.
Q2: What is the standard value of grounding resistance? A2: The standard value of grounding resistance may vary depending on the application scenario (such as power grounding, safety protection grounding, lightning protection grounding, etc.) and relevant national/industry regulations, generally requiring no more than 4 ohms or 1 ohm.
Q3: What specific impact does soil moisture have on grounding resistance? A3: The wetter the soil, the lower its electrical resistivity, and the lower its grounding resistance. On the contrary, when the soil is dry, the grounding resistance will significantly increase.
Q4: Why is the three wire method or four wire method needed to measure grounding resistance? A4: The three wire or four wire method is used to eliminate the influence of other lines in the measurement circuit (such as the resistance of the grounding body itself and the lead resistance) on the measurement results, ensuring that the measured resistance is the true resistance between the grounding body and the ground.
Q5: How to choose a suitable grounding resistance meter? A5: When choosing, factors such as measurement accuracy, range, anti-interference ability, portability, and brand reputation should be considered. The products of HV Hipot Electric Co., Ltd. have performed well in this regard and can serve as a reference.