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 Verification Regulation of Loop Resistance", 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 bridge was often used to measure the contact resistance of circuit breakers. However, when using a double bridge to measure the conductive loop resistance of a circuit breaker, because the measurement circuit of the double bridge passes a weak current, it is difficult to eliminate the oxide film with high resistance, resulting in a larger measured resistance value. 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 a high-voltage circuit breaker mainly depends on the contact resistance between its moving and static contacts. The existence of contact resistance increases the loss when the conductor is energized, raising the temperature at the contact point. Its value directly affects the current-carrying capacity during normal operation and, to some extent, the ability to interrupt short-circuit currents. Therefore, the conductive loop resistance of each phase of the circuit breaker is an important data item for installation, maintenance, and quality acceptance.
Loop Resistance Tester Assembly (3 photos)
Due to the oxide film between switch contacts, if a small current is used for detection, the test results are generally much larger due to the influence of the oxide film. However, 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 current, the better. But when formulating the regulations, considering the production level of relevant domestic instruments at that time, a provision was made 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 applied to the connection points of grounding down conductors during the construction of grounding devices, the connection points in the soil are still affected by moisture and other factors for a long time, leading to corrosion, disconnection, loosening, and other phenomena, resulting in increased resistance at the contact points between the grounding down conductor and the grounding grid, failing to meet the requirements of power regulations, causing potential safety hazards during equipment operation, and in severe cases, causing equipment to detach from the grounding grid.
Loop Resistance Tester (3 photos)
It can be used for precise 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 grounding down conductors, and to determine fault points by comparing historical test values and adjacent point test values. 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, featuring 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, capable of stably outputting large current for a long time, complying with the relevant provisions of DLT845.4-2004 "General Technical Conditions for Resistance Measuring Devices Part 4: Loop Resistance Tester".
Technical Parameters
Edit
1. Measurement range: 0~4mΩ (50A gear) 0~2mΩ (100A gear) 0~1.33mΩ (150A gear) 0~1mΩ (200A gear)
2. Test current: DC 50A, 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
Edit
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 value is displayed, save the data if needed.
5. After the measurement, please turn off the power.
6. Please take care of the test clamps.
