During the design and selection stage, attention is focused on parameter specifications, but after the equipment is put into operation, what truly affects measurement results is the maintenance process. A zinc oxide arrester tester consists of three parts: a 0–30 kV numerically controlled high-voltage power supply, a high-voltage output line, and a leakage current signal acquisition line. Any change in the state of any part will be reflected in the readings of the 1 mA test voltage and the leakage current at 0.75 times that voltage. Field maintenance should be carried out separately around these links.
High-voltage output circuit: insulation and grounding first. After long-term bending and dragging, the outer insulation of the high-voltage output cable may become worn, forming a leakage path during voltage rise and causing the U1mA measurement value to be low. Before use, visually inspect the cable sheath to confirm there is no damage and no excessive squeezing; the grounding terminal must be reliably connected to avoid interference introduced by poor common grounding between the acquisition circuit and the high-voltage circuit. The numerically controlled power supply has two operating modes: constant voltage and constant current. After maintenance, it is advisable to first perform a constant-voltage voltage-rise verification with a test object known to be in good condition, confirming that the voltage rises smoothly without jumps.
Current sampling stage: pay attention to range and shielding. The leakage current signal is sampled from the current lost when high voltage is applied to the test object. The measurement range of total current and resistive current is usually 0–20 mA. The sampling circuit is sensitive to stray electric fields, so field wiring should minimize the length of signal lines and keep them away from high-voltage busbars and high-current conductors. If the reading still has an obvious base value when no test object is connected, first check the connection status of the signal line shielding layer, and then determine whether the acquisition unit needs calibration.
Parameter coverage and applicable boundaries. The measurement range of the initial operating voltage U1mA covers 10–2000 V, and the voltage acquisition range is 30–250 V, making it suitable for testing zinc oxide arresters of 10 kV and below. If the voltage level of the test object exceeds this range during design and selection, the instrument range should be checked separately to avoid distorted readings caused by use beyond the range. Daily storage should be moisture-proof and dust-proof. Before reusing after long-term shutdown, it is recommended to first perform a no-load voltage-rise check to confirm that the power supply output is consistent with the display before entering field measurement.
