Ground Resistance Tester for Loop Impedance Testing?

How do we perform ground fault loop impedance testing?

HMHL-100A Loop Resistance Tester.

It is recommended to perform an external ground loop impedance (ZE) test first. This test is done on the switchboard and gives the loop impedance of the circuit, excluding the installation. Next, a system loop impedance test (ZS) must be performed, which includes the circuits tested in the ZE test, as well as the mounting resistors.

The AC impedance of a circuit may differ from its DC resistance – especially for circuits with a current rating of more than 100 A – so the fault loop impedance is measured using the same frequency as the nominal supply frequency (50 Hz).

The ground fault loop impedance measurement is carried out on the power supply side of the switchboard and on the main grounding mode, with the main switch open and all circuits isolated. During the test, the grounding device will be connected and isolated from the installed grounding system (grounding rod). The ZE measurement will confirm that the ground fault loop impedance is the sum of the resistances.

Earth Resistance Tester.

It is divided into a large ground grid grounding resistance tester and a grounding resistance meter. The two are different in terms of function, scope, etc. The large-scale ground grid grounding resistance tester can meet the measurement of ultra-large and large-scale conventional grounding grids. It can be used to accurately measure ground impedance, ground resistance, ground reactance.

Surface potential gradient, contact voltage, contact potential difference, step voltage.

Parameters such as step potential difference, transfer potential, on-resistance, soil resistivity, and current distribution of the ground grid fully meet the requirements of the new version of DL T475-2006 "Guidelines for the Measurement of Characteristic Parameters of Grounding Devices". The Ground Resistance Meter is suitable for the measurement of small resistances. The grounding resistance meter abandons the traditional manual hand-cranked power generation working method, adopts advanced large-scale integrated circuits, and uses DC AC conversion technology to combine the measurement methods of the three-terminal button and the four-end button into a new type of digital grounding resistance tester of one model.

It is suitable for measuring the grounding resistance of various devices and measuring the conductor resistance value of low resistance in electric power, post and telecommunications, railway, communication, mining and other departments; It can also measure soil resistivity and ground voltage. The earth resistance tester should be kept indoors to maintain its ambient temperature of 0 40 and relative humidity.

No more than 80 and no harmful substances in the air that can cause corrosion.

The Ground Resistance Meter is suitable for the measurement of small resistances. The grounding resistance meter abandons the traditional manual hand-cranked power generation working method, adopts advanced large-scale integrated circuits, and uses DC AC conversion technology to combine the measurement methods of the three-terminal button and the four-end button into a new type of digital grounding resistance tester of one model. It is suitable for measuring the grounding resistance of various devices and measuring the conductor resistance value of low resistance in electric power, post and telecommunications, railway, communication, mining and other departments; It can also measure soil resistivity and ground voltage.

The grounding resistance tester should be kept indoors to maintain its ambient temperature of 0 40, the relative humidity should not exceed 80, and the air should not contain harmful substances that can cause corrosion.

Main role. 1.Accurate measurement of grounding impedance, grounding resistance, and grounding reactance of large grounding grids;

2.Accurate measurement of the surface potential gradient in the field area of a large grounding grid;

3.Accurate measurement of contact potential difference, contact voltage, step potential difference and step voltage of large grounding grids;

4.Accurate measurement of large ground grid transfer potential;

5.Measure the on-resistance of the ground down lead;

6.Measure soil resistivity.

The grounding resistance meter is to measure the performance of the equipment, the smaller the value, the better, indicating that the grounding is good.

The insulation of the measurement line is called a megohmmeter, and the larger the value, the better, indicating that the insulation and electricity do not connect you.

Wrong! A ground resistance tester is an instrument that measures whether the ground wire is good or not.

1. Grounding resistance tester is a common instrument for testing and measuring grounding resistance, and it is also an indispensable tool for electrical safety inspection and grounding engineering completion acceptance.

2. At present, the advanced ground resistance tester can meet the requirements of all grounding measurements. Using the new jaw method, there is no need to drive and install piles and pay-offs for direct measurement of volts. A powerful ground resistance tester is controlled by a microprocessor, which can automatically detect the connection status of each interface and the interference voltage and frequency of the ground network, and has unique functions such as value holding and intelligent prompts.

Clamp grounding resistance meter is a major breakthrough in traditional grounding resistance measurement technology, clamp grounding resistance meter in the measurement of the grounding system with loops, no need to disconnect the grounding lead, no need for auxiliary electrodes, safe, fast, easy to use.

3. The clamp grounding resistance meter can measure the grounding fault that cannot be measured by the traditional method, and can be applied to the occasion that the traditional method cannot measure, because the clamp grounding resistance meter measures the comprehensive value of the resistance of the grounding body and the resistance of the grounding lead. Clamp earthing resistance meters are divided into long jaws and round jaws. The long jaws are particularly suitable for the occasion of flat steel grounding.

The measurement of grounding resistance is a simple process, only the measurement is good, in order to ensure the follow-up work, but also pay attention to the maintenance of the grounding resistance meter, so as not to affect the measurement data. So how to test the grounding resistance, and how to maintain the grounding resistance meter, do you understand? Now let's take a look.

1. How to test the grounding resistance.

1. Prepare instruments, such as instrument boxes, grounding rods, and test wires; 2. Select two grounding rods to insert into the ground and access the ground level; 3. Insert four grounding rods into the ground again, with a spacing of 5m; 4. Set the current end to be red and the voltage end to be yellow; 5. Green and yellow are connected to the grounding wire of the equipment; 6. Rotate the switch to measure the resistance.

Second, how to maintain the grounding resistance meter.

1. When the grounding resistance meter is stored, it must be selected in the right place, and it cannot be stored in a humid area, otherwise it is easy to cause the grounding resistance meter to get wet. Under normal circumstances, the grounding resistance meter is stored in a dry and well-ventilated area, which can increase the service life of the resistance meter and make the measurement data more accurate.

2. In the process of measuring the grounding resistance with the instrument, it is best to close the connection points between the electrical facilities and the power supply. If the measured ground resistance is less than 1 ohm, it is necessary to connect the special wire to the ground, and ensure that the C terminal is on the outside and the P terminal is on the inside, so as to avoid a large error in the measured data.

3. If the detected grounding resistance is relatively large, the size of the resistance cannot be measured by the wiring method, but the insertion point of the wire needs to be selected according to the measurement method of the ammeter and voltmeter. In addition, the resistance value needs to be measured multiple times at different positions, and then averaged to make the error smaller.

About how to test the grounding resistance, and how to maintain the grounding resistance meter, it is introduced here, do you understand? It is not difficult to measure the ground resistance, the key is to take the average value of several measurements, so as to reduce the error of the measured value.

There are 5 ways to measure ground resistance, which are as follows:

1.Two-wire method conditions: There must be a ground with a known good ground, such as pen, etc., and the measured result is the sum of the resistance of the ground being measured and the ground being known. If the known ground is much smaller than the resistance of the ground to be surveyed, the measurement results can be taken as the result of the ground surveyed.

2.Three-line method conditions: There must be two book disturbing Kai grounding rods:

An auxiliary ground and a probe electrode. The spacing between the ground electrodes is not less than 20 meters. The principle is to add a current between the auxiliary ground and the ground to be measured to measure the voltage drop between the ground to be measured and the probe electrode, and the measurement results include measuring the resistance of the cable itself.

3.The four-wire method is basically the same as the three-wire method, replacing the three-wire method when measuring low ground resistance and eliminating the effect of the resistance of the measured cable on the measurement results. E and ES are to be connected directly to the ground to be measured separately.

4.The single-clamp measurement measures the ground resistance at each ground point in the multi-point ground, and the ground connection cannot be disconnected to prevent danger.

5.Double clamp method conditions: multi-point grounding, no auxiliary ground pile, measurement of single grounding. Wiring: Use the current specified by the manufacturer to clamp to the corresponding socket, and clamp the two clamps on the grounding conductor, and the interval between the two clamps should be greater than meters.

Expand your knowledge:

What are the types of ground resistance?

1.Protective grounding: most of the shells of this electrical equipment are metal, and the shell will be worn out after a long time, resulting in damage to the insulator and thus electrification, in order to avoid electric shock accidents, we must use grounding resistance when installing electrical equipment, so as to avoid the occurrence of electric shock accidents.

2.Anti-static grounding: This kind of grounding, which is mostly required for fuel and natural gas electronic equipment, can avoid the danger caused by static electricity.

3. Lightning protection and grounding: The destructive power of lightning is very large, usually during thunderstorms, there are often accidents where trees are struck by lightning or people are struck by lightning. In order to reduce the destructive power of lightning, we can lead lightning to the ground, and we can install lightning protection equipment on buildings, such as lightning rods and other state calls, which can effectively protect the safety of people's lives and property.