Loop Resistance Tester with Printing
In the power system, many high-current electrical equipment require accurate measurement of loop resistance during preventive tests and handover tests. Circuit breakers are important electrical equipment in the power system. According to the latest standard "JJG1052-2009 Loop Resistance Verification Regulation", national standards GB763, GB50150, and power industry standard DL/T596, the measurement of the conductive loop resistance of circuit breakers is specified: the DC voltage drop method should be used, with a current not less than 100A.
The resistance of the conductive loop of a circuit breaker mainly depends on the contact resistance between its moving and static contacts. There are many methods to measure contact resistance. Japanese scholar Isao Minowa proposed using superconducting quantum devices to measure contact resistance, H.Archi proposed using the electrolytic cell method, and Polish scholar Jerzy Kaczarek proposed using the third harmonic method. These methods are generally used in laboratory conditions for electrical contact research. In engineering, the four-terminal method is usually used to measure the contact resistance of actual contacts.
Previously, a DC double-arm bridge was often used to measure the contact resistance of circuit breakers. However, when using a double-arm bridge to measure the conductive loop resistance of a circuit breaker, because the measurement loop of the double-arm bridge passes a weak current, it is difficult to eliminate the oxide film with high resistance, and the measured resistance value tends to be larger. However, the oxide film can be easily broken down under a large current, which does not hinder the normal current flow. Therefore, when using the DC voltage drop method for testing, the current should not be too small.
The resistance of the conductive loop of high-voltage circuit breakers mainly depends on the contact resistance between the moving and static contacts. The existence of contact resistance increases the loss when the conductor is energized, raises the temperature at the contact point, and its value directly affects the current-carrying capacity during normal operation, and to a certain extent affects the ability to interrupt short-circuit current. Therefore, the conductive loop resistance value of each phase of the circuit breaker is an important data for installation, maintenance, and quality acceptance of circuit breakers.
Loop Resistance Tester Assembly (3 pictures)
Due to the oxide film between switch contacts, if a small current is used for detection, the test result is generally much larger due to the influence of the oxide film, but the oxide film can be broken down under a large current. Theoretically, as long as the test current does not exceed the rated current, the larger the better. However, when formulating the regulation, considering the production level of relevant domestic instruments at that time, it was stipulated that the current should not be less than 100A. Ground Continuity Resistance Tester for Power Equipment
The reliable and effective connection between the grounding down conductor of power equipment and the grounding grid is the fundamental guarantee for the safe operation of power equipment and the personal safety of operators. Although necessary anti-corrosion treatment has been done at the connection of the grounding down conductor during the production of the grounding device, the connection point in the soil is still affected by moisture and other factors for a long time, leading to corrosion, disconnection, loosening, and other phenomena, resulting in an increase in the contact resistance between the grounding down conductor and the grounding grid, which cannot meet the requirements of power regulations, causing hidden dangers in equipment operation, and in severe cases, causing equipment to be disconnected from the grounding grid.
Loop Resistance Tester (3 pictures)
It can be used for accurate measurement of the continuity resistance between the grounding down conductor of power equipment and the grounding grid or adjacent equipment.
The Ground Continuity Resistance Tester is used to measure the continuity resistance of the grounding down conductor, and determine the fault point by comparing the historical test values and the test values of adjacent points. The working power of the Ground Continuity Resistance Tester is provided by an internal lithium battery, no external AC power supply is needed. The test process is controlled by a microcontroller, with the characteristics of simple operation, fast test speed, stable test data, and portability.
Since the contact resistance of circuit breakers is very small, only a high current can ensure certain accuracy and stronger anti-interference ability.
It is used for high-precision measurement of circuit breaker contact resistance and current-carrying conductor resistance, can output large current stably for a long time, and complies with the relevant provisions of DLT845.4-2004 "General Technical Conditions for Resistance Measuring Devices Part 4: Loop Resistance Tester".
Technical Parameters
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1. Measurement range: 0~4mΩ (50A gear) 0~2mΩ (100A gear) 0~1.33mΩ (150A gear) 0~1mΩ (200A gear)
2. Test current: DC50A, 100A, 150A, 200A fixed output
3. Measurement accuracy: ±(0.5% rd+2d)
4. Continuous working time: 5s~599s
5. Display mode: large screen Chinese LCD display
6. Communication method: RS232 serial port
7. Working power: AC220V±10% 50Hz
8. Total power: 1200W
Operating Procedure
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1. Connect the wires according to the four-terminal method.
2. Turn on the power.
3. Press the measurement key (if the current display A value is less than 100A, it can be corrected through the panel current fine-tuning).
4. After the measurement display value, save the data.
5. After the measurement, please turn off the power.
6. Please take care of the test clamps.
