KDHL-100A Loop Resistance Tester

KDHL-100A Loop Resistance TesterOverview

KDHL-100A Loop Resistance TesterMade using high-power switching power supply technology and refined electronic circuits. It is a specialized testing instrument for high and low switches, cable wires, and weld contact resistance. Its current adopts the standard DC recommended by the national standard GB736, and the resistance value of the test sample can be measured at the standard current. This instrument has the characteristics of small size, light weight, strong anti-interference ability, high accuracy, easy operation, and protective function.

2、 Product Features

1. Color touch screen: 800 × 480 high-definition color 7-inch touch screen, human-machine dialogue, high-speed thermal printer.

2. Multi current output: Using the latest power technology, it can continuously output high current for a long time, with multiple current output levels. 1-3 different current levels can be set for testing, and the average value can be automatically calculated.

3. Display multiple data: display resistance, voltage, current, resistivity, and display the resistance value converted to standard temperature.

4. Automatic over limit alarm: Set the upper limit of resistance, and if the resistance value is qualified, over limit, or invalid, the test state will be automatically generated.

5. Can be tested for a long time: The measurement time can be set from 0-9999S and can work for a long time. Built in cold air cooling, automatic thermal protection for switch power supply. (Customized)

6. High precision measurement: Precision instrument operational amplifiers and high-precision quadruple integrator A/D converters were used.

7. Latest system chip: Using high-performance 32-bit latest ARM chip, the system automatically switches the amplification factor according to the signal size during measurement, ensuring the accuracy of the product's testing.

8. Built in calendar clock: Built in calendar clock provides a time basis for printing and saving data.

9. DC constant current source function: It can output 0-maximum current and has a built-in step-by-step current rise test. It is recommended to buy one * DC constant current source, which can be used for multiple purposes.

10. Massive storage of experimental data: This machine is equipped with large capacity storage to store massive amounts of data. It has data storage and browsing functions, as well as power failure protection function.

11. Exporting test data from USB drive: equipped with USB drive data export function, exporting Excel files.

12. Standard Modbus RTU: equipped with RS232 interface (optional to be changed to RS485), communication protocol is standard Modbus RTU.

13. Computer control and data upload: Equipped with an RS232 upper computer, communication can control, upload, and generate word/Excel files.

14. Bluetooth control and data upload: Equipped with Bluetooth function as standard and an Android Bluetooth APP, it can control, upload, and generate Word files.

15. Line control operation, convenient for assembly line operation: Line control mode (optional), can be controlled by an external line switch (closed/open) to test/interrupt, and if the resistance exceeds the limit, the output empty node can light up the alarm light.

16. Wireless remote control, fast and convenient: optional remote control (optional), one click test, one click interrupt test, customizable remote control to display test status.

17. Temperature compensation automatic conversion resistance: It can preset the temperature and automatically convert the resistance value at standard temperature. Temperature sensors (optional) can also be used to measure the temperature.

18. Easy switching of background color: You can set the screen color, which can be changed to blue background or black background, and set the background brightness, standby brightness, and standby time

19. Built in training materials: The screen is equipped with various wiring methods to guide on-site use.

20. Chinese input of experimental information: Relevant sites, equipment, personnel, notes, etc. can be entered in Chinese for easy identification and storage of experimental data, as well as for easy identification and printing of experimental data.

21. Fast connection of high current wire: Use the latest connection interface of high current wire, insert and twist it, it is fast and convenient.

22. Multiphase function selection: The standard configuration is single-phase, and it can be selected as two phase simultaneous measurement (dedicated conductor resistance tester) or three-phase simultaneous measurement.

IIIKDHL-100A Loop Resistance TesterTechnical Specifications

KDHL-100A Loop Resistance TesterExplanation of Electrical Working Principles

The resistance value of the test sample can be measured under the condition of 100A/200A DC current recommended by the national standard GB736. The instrument has the characteristics of small size, light weight, strong anti-interference ability, high accuracy, easy operation, and protection function. The circuit resistance tester of domestic manufacturers adopts the four terminal method for testing, using a high-frequency switch power supply to generate a test current greater than 100A. When the measurement button is pressed, the high-frequency switch power supply outputs a test current greater than 100A. At the same time, the sampling circuit starts to sample the voltage input terminal and internal current divider voltage. The obtained signal is amplified by an amplifier, converted into a digital signal by an A/D converter, and then filtered, operated, and processed by a microprocessor before being sent to the display to display the measured current and resistance value.

The above principle works well in normal laboratory testing, and when the current test circuit breaks or contacts * *, the instrument will determine that the current circuit is open based on the voltage on the current divider. But when there is contact or open circuit in the voltage wiring circuit, the tester will also display a value, and the following situations will occur:

1) The voltage circuit is open or in contact with * *, and there is no strong electric field interference at the testing site as shown in Figure 1:

Figure 1

R1 in the figure represents the resistance in the voltage line circuit of the circuit resistance tester. When the voltage line breaks, the resistance of R1 is infinite, and sometimes there may be an oxide film or oil film on the wiring board of the circuit breaker. When the voltage test clamp of the circuit resistor is connected to such a terminal block, contact may occur. The tested contact resistance is not infinite, nor is it small enough to be ignored (for the input resistance of voltage sampling). In this case, the relationship between the data displayed by the circuit resistance tester and the actual resistance value data of the test sample is as follows:

Assuming the resistance of the test sample is Rx, the input internal resistance of the voltage sampling circuit is Ri, and the current sampling is not affected. The value displayed by the instrument is Rx * Ri/(R1+Ri), which is slightly smaller than the actual measured resistance. If the resistance value Rx of the test sample has exceeded the * * range at this time, but the value displayed by the instrument may be within the qualified range, it is easy for the testing personnel to make misjudgments and create * * hidden dangers.

2) When the voltage circuit is open or in contact with * * (the visible contact resistance R1 is infinite when open), there is strong electromagnetic interference at the test site as shown in Figure 2:

At this time, the live busbar interferes with two voltage test lines through capacitors with air as the medium. Due to the interference, a differential mode voltage appears at both ends of the voltage acquisition line of the circuit tester. If the interference is large, the circuit resistance tester will display a much larger value than the resistance value of the test sample. At this time, the tester will determine that there is a problem and solve it to obtain the correct value.

If the intensity of interference is not very high and the instrument test value is exactly within the qualified resistance range of the circuit breaker, the testing personnel generally believe that the data is correct, which can lead to misjudgment and false data, causing * * hidden dangers.