The proper functioning of secondary circuit testing equipment directly affects the accuracy of test data and the safe operation of the power system. Determining its operational status requires a comprehensive evaluation of four aspects: visual inspection, power-on self-test, benchmark testing, and periodic calibration.
1. Visual Inspection and Wiring Check: Inspect the equipment casing for damage, ensuring there are no cracks, deformations, or burn marks.
Confirm that the test cables are undamaged, the plugs are secure, and the clamp meter jaws are clean and tightly closed.
For four-terminal resistance testers, ensure that the current and voltage lines are independent and not short-circuited.
If physical damage is found, the equipment may be malfunctioning and should be discontinued.
2. Power-on Self-test and Function Verification: After powering on, observe whether the equipment completes the self-test process (e.g., screen display, indicator light flashing, buzzer sound).
Check the system menu for error codes or alarm messages (e.g., "open circuit," "over-temperature," "synchronization failure"). After entering the main interface, try switching measurement modes (e.g., CT/PT load, voltage drop, resistance) to confirm normal operation response.
3. Benchmark Testing (Comparison Method) Perform cross-validation using standard loops or similar equipment with known parameters:
Inductor Load Tester: Test on a simulated load with known impedance values and compare reading deviations to see if they are within the allowable range (generally ≤±3%).
Voltage Drop Tester: By shorting the master and slave input terminals, the expected voltage drop should be close to 0%. An abnormal reading indicates a sampling channel fault.
Loop Resistance Tester: Use a standard resistor (e.g., 100μΩ) for measurement and determine if the results are consistent.
It is recommended to perform a quick benchmark test before daily operation to ensure the equipment is in a reliable state.
4. Periodic Calibration and Certificate Verification All secondary testing equipment should be submitted for inspection annually to obtain a calibration certificate issued by a metrology institution.
Check the next calibration date on the equipment label before use. Expired equipment must not be used for formal testing.
Calibration items should include key indicators such as accuracy, linearity, and anti-interference capability.
Special reminder: After prolonged operation in humid, high-temperature, or strong electromagnetic environments, it is recommended to immediately conduct an on-site comparison test to prevent equipment drift caused by environmental factors.
