ET3000 Double Jaw Grounding Resistance Tester

ET3000 Double Jaw Grounding Resistance Tester

1、 Introduction
Welcome to use the high-quality professional testing instrument ET3000 dual clamp multifunctional grounding resistance tester. This instrument is used for measuring grounding resistance and evaluating grounding quality based on it. This instrument is designed and manufactured based on our years of experience in the production and development of grounding resistance and electrical installation testing equipment.
The ET3000 dual clamp multifunctional grounding resistance tester is a handheld grounding measuring instrument. The instrument is equipped with necessary accessories for testing. The operation is simple and intuitive, and the operator only needs to read the manual without attending specialized training to operate.

2、 Overview
A good grounding system is an important guarantee for the safe and reliable operation of power, telecommunications, and electrical equipment. The size of the grounding resistance is the basis for evaluating the quality of the grounding system. A fast, simple, and reliable method for measuring grounding resistance has become an urgent need for technological progress in the field of lightning protection and grounding. The ET3000 dual clamp multifunctional grounding resistance tester is suitable for telecommunications, power, meteorology, computer rooms, power distribution lines, iron tower transmission lines, gas stations, factory grounding grids, lightning rods, etc.
This instrument not only has the function of traditional auxiliary ground measurement of grounding resistance, but also has the function of non auxiliary ground measurement, which changes the traditional measurement principle and method of testing grounding resistance: using double jaw non-contact measurement technology does not require auxiliary ground, nor does it need to isolate the grounding body from the load, achieving online measurement. Under conditions such as single point grounding system and strong interference, auxiliary grounding measurement can be used for measurement.

IIIET3000 Double Jaw Grounding Resistance TesterMain Features
1. Double clamp method/ground pile method dual measurement method:
Suitable for any grounding location, multiple or single point grounding, can be tested normally;
2. Strong anti-interference ability:
Self-produced high-frequency current to filter out harmonic interference currents such as 50Hz and 100Hz in the mains power supply, which can be measured even in a 500KV substation environment;
3. Wide measurement range and high resolution:
The range is from 0.01 Ω to 200 Ω, with a resolution of 0.01 Ω. It can also accurately measure grounding resistance below 0.7 Ω;
4. Large jaw design:
Jaw diameter 50mm (standard configuration), suitable for using flat iron/steel as grounding lead, special jaw size can be customized according to customer requirements;
5. Large capacity data storage:
Can store 200 sets of measurement data;
6. Easy to operate, single person assignment:
Full Chinese operation interface, small size, light weight, explosion-proof portable case, easy to carry for field measurement.

4Main technical indicators
1. Measurement range of grounding resistance:
Double clamp method: 0.01 Ω~200 Ω
Ground pile method: 0.01 Ω~200 Ω
2. Accuracy:
Double clamp method: ± 3% ± 2 words
Ground stake method: ± 2% ± 2 words
3. Small resolution: 0.01 Ω
4. Jaw size: Φ 50mm
5. Storage capacity: 200 sets of data
6. Working temperature: 0 º C to+50 ° C
7. Power supply method: 8 5-gauge nickel hydrogen rechargeable batteries or ordinary AA batteries
8. Weight: 0.8KG (including battery)
9. Size: 265mm × 130mm × 65mm

5、 Introduction to Panel Functions
1. Key function
There are seven buttons on this machine, with specific functions as follows:
Power supply: power on key; After booting up, if no action is taken for 5 minutes, it will automatically shut down.
Double clamp method ▲: This method is used for testing in a multi-point grounded grounding network; Additionally, in other functions, this key serves as an up cursor or an increase key.
Ground Pile Method ▼ ": Press this key to measure the grounding resistance by driving auxiliary ground piles. In addition, for other functions, this key is a downward cursor or a decrease key.
Left arrow key.
Right arrow key for cursor movement.
Test ": When using the double clamp method or ground pile method for measurement, press this button to start the measurement.
Confirm: Press this key to enter the selected function.

2. Test port (as shown in Figure 1)

Figure 1 Panel Terminal
The instrument has two sets of interfaces connected to the outside world: the dual clamp method uses the upper "receiving" and "transmitting" aviation plugs; The ground pile method uses four sockets at the bottom, namely "C2", "P2", "P1", and "C1".
The charging socket is located at the bottom left of the instrument. When the battery level indicator in the upper left corner of the instrument display screen drops, please use the ground resistance meter charger provided by our company for charging. This charger is an intelligent charger that automatically stops charging the battery when the battery is fully charged, i.e. when the charger indicator light goes out, effectively preventing overcharging of the battery.
Attention: When the instrument is not used for a long time, the battery should be charged regularly (such as for two months) to avoid excessive discharge and damage to the battery. Do not charge with regular batteries.

6、 Measurement principle and usage method
1. Double clamp method
1. Measurement principle
The advantage of this method is that it is easy to operate. The test can be conducted without turning on the power supply of the device under test while it is working normally. There is no need to insert a measuring probe or separate the measured electricity. Simply clamp the grounding conductor with double clamps to measure its grounding resistance. The second is high precision. Its accuracy can reach 0.01 Ω. Thirdly, it has strong anti-interference ability. It can filter out various power frequency harmonics. Fourthly, it can serve as a supplement to the method of piling. In many conditions (such as densely populated or cement covered areas), it is difficult or even impossible to measure the grounding resistance using pile driving. By using the double jaw testing principle, it is possible to measure without using a grounding pile. The limitation of this measurement principle is that it cannot directly measure a single point grounding system. Clamp on meters should be used with caution in single point grounding systems.
The measurement principle is briefly described as follows: This instrument is equipped with two clamps: voltage clamp and current clamp.
As shown in Figure 2, the voltage clamp excites an induced potential E in the tested circuit and generates a current I in the tested circuit. The instrument can measure the value of I through the current clamp. By measuring E and I, the value of R can be obtained using Ohm's law: R=E/I.

Figure 2 Measurement principle
2. Measurement of multi parallel connected ground resistance
For multi-point grounding systems (such as transmission tower grounding, communication cable grounding systems, certain buildings, etc.), they are connected through overhead ground wires (shielding layers of communication cables) to form a grounding system. As shown in Figure 3:


Figure 3 Measurement of Ground Resistance in Multi point Grounding System
When using a clamp gauge to clamp two jaws onto the tested grounding wire, with a distance of about 30cm between the jaws, insert the launch clamp into the "launch" socket and the receive clamp into the "receive" socket. The two sockets are not interchangeable (as measured in the above figure), and their equivalent circuit is shown in the following figure.

Then RT=Rx+R0
among which
RT: The value measured by the instrument
Rx: Ground resistance to be tested
R0: The equivalent resistance of the grounding resistance of all other towers in parallel.
Although, strictly speaking, due to the existence of so-called "mutual resistance" in grounding theory, R0 is not the usual parallel value in the electrical engineering sense (it will be slightly larger than the parallel value in the electrical engineering sense), because the grounding hemisphere of each tower is much smaller than the distance between towers, and after all, there are a large number of grounding points, R0 is much smaller than R1. Therefore, it can be reasonably assumed from an engineering perspective that R0=0. In this way, the resistance we are measuring should be RX, that is, RT ≈ Rx.
Multiple comparative experiments with traditional methods have been conducted in different environments and situations, proving the validity of the above hypothesis.
Non contact measurement method (i.e. double clamp method) is a measurement technique with many advantages. However, the resistance measured by the tester is the resistance of the entire circuit, including the measured ground resistance. This must be kept in mind during use to facilitate the analysis of measurement results.
Attention: The transmitting clamp and receiving clamp are not interchangeable.
3. Method of measuring independent grounding body using double clamp method
a、 The double clamp method must have an effective closed loop during the testing process. The solution is to find an auxiliary power supply, connect the tested grounding body to a well grounded auxiliary ground (such as a water pipe) with a connecting wire, and clamp two pliers into the connecting wire (as shown in Figure 5): the distance between the two is about 30cm. At this time, press the "double pliers" button to perform the double pliers measurement interface, and then press the "test" button to directly display the measurement results. When testing the grounding resistance of an independent grounding body, different testing methods can be used according to different situations.
b、 When the computer room is located on a lower floor (first or second floor), the ground pile testing method can be used to directly measure the grounding resistance.
When the computer room is located on a higher floor (above the second floor), the "independent grounding body" testing method can be used. This method is based on the theoretical assumption that the grounding resistance of the water supply pipe network is zero ohms, but in reality it has a resistance value. At this time, the testing is divided into two steps: * step, measure RA according to the "independent grounding body" testing method; the second step, measure RB of the grounding resistance of the water supply pipe separately on the first floor according to the "ground pile" testing method (at this time, the water supply pipe is regarded as an independent grounding body), and (RA-RB) is the actual grounding resistance of the computer room grounding device.



Figure 5 Measurement of Ground Resistance of Independent Grounding Body
When using the double clamp method to measure resistance, if the measured value shows overflow, it indicates that the measured resistance has exceeded the measurement range of this instrument or that the clamp is not clamped around any metal conductor or the tested grounding wire.
II. Ground Pile Method
Use the connection method shown in Figure 6. At this point, press the "Ground Pile" button to enter the Ground Pile Test interface. Press the "Test" button again to further measure the grounding resistance value of the tested grounding body.

3. Storage
After each measurement, the measurement results can be stored. Press the left or right arrow key to stop the cursor on "Storage", and press the "Confirm" key to enter the storage function. Enter the item number to be stored or viewed, and then press "confirm" to store it. For example, if you want to store the measurement data in Group 7, adjust the item number to 007. Press the 'Confirm' button again to confirm and complete the storage. If the item number already contains data, the original data will be overwritten. Continue testing, press the 'Confirm' button to return to the testing state. This machine can store 200 sets of data.
4. View/Delete
On the testing interface of the double clamp method and ground pile method, move the cursor to "Return", then press the "Confirm" key to enter the main menu on the right, and then press the "▲" and "▼" keys to select "View Historical Data" or "Delete Historical Data". Press the 'Confirm' button again to enter the corresponding function. Adjust left and right by pressing "" "", adjust numbers by pressing "▲" and "▼", and confirm by pressing the "confirm" button to view or delete stored values.
5. Maintain
During the testing process of the double clamp method and ground pile method, numerical instability may occur due to environmental influences and external disturbances. On the testing interface of the double clamp method and ground pile method, when the cursor is on "hold", the measurement value can be locked by pressing the "confirm" button, making it easier for the measurer to record and read the value. At this point, the 'hold' button on the screen changes to 'unlock'. Press' confirm 'again to unlock the function.

7、 Precautions
1. The jaws and the host are used in conjunction and have been pre configured as required before leaving the factory. To avoid measurement errors, the jaws provided with this host should not be used on other hosts.
2. At all times, it is necessary to protect the cleanliness of the contact surface of the clamp iron core, as contaminated clamps can reduce the measurement accuracy of the instrument.
3. During testing, the jaws should be kept tightly closed and there should be no jamming phenomenon.
8、 Supporting attachments
1. Host (including 8 rechargeable batteries) 1 unit
2. One verification ring
3. One set of testing line
4. Winding rack (20 meter black line, 40 meter red line) 1 set
5. Two ground stakes
6. One charger
7. Test 2 pliers
8. One aluminum alloy outer box
9. One manual
10. One factory inspection report
11. One certificate of conformity