As a critical protective device in electrical systems, the performance of SAPs directly impacts the safety of equipment and personnel. Regular inspection is crucial to ensure reliable operation during lightning or surge events. This article details the standardized inspection process for SAPs
Appearance and Installation Inspection
Inspection begins with the appearance of the SAP housing, checking for signs of cracks, burns, or deformation. Terminals should be tightened and clearly labeled. Also, confirm that the installation location complies with regulations, the grounding wire is securely connected, and the grounding resistance meets design requirements (typically ≤10Ω).
Varisor Voltage Test
Use a varistor voltage tester to measure the nominal on-state voltage of the SAP. Connect the tester to both ends of the SAP and read the voltage at a specified current (e.g., 1mA DC). Compare the voltage to the nominal specifications. Deviations exceeding ±10% may indicate device aging or performance degradation.
Leakage Current Test
Measure the SAP's leakage current (typically <20μA) at normal operating voltage. Excessive leakage current may indicate internal insulation degradation, requiring further analysis. During testing, ensure a stable environment to avoid interference that could affect data accuracy.
Operation Load Test (Optional)
For critical equipment, a simulated lightning surge (e.g., 8/20μs waveform) can be used for operation testing. A surge generator applies a standard energy (e.g., 10kA) to observe whether the arrester effectively clamps the voltage and conducts the shunt. After the test, retest the varistor voltage and leakage current to confirm that the device is intact.
Records and Conclusions
Completely record all test data, including test time, environmental conditions, and results. If any parameters exceed the specified value, physical damage, or abnormal operation is detected, the arrester should be replaced immediately and the cause identified. A final inspection report should be issued, clearly indicating the device's status and providing subsequent maintenance recommendations.
A standardized inspection process can effectively extend the life of the arrester and ensure safe system operation. It is recommended to shorten the inspection interval based on the operating environment (e.g., in areas with frequent thunderstorms) to prevent potential problems.
