The leakage current flowing through a zinc oxide arrester under continuous operating voltage is mainly capacitive; although the resistive component is small, it directly reflects valve element degradation and moisture ingress. The YHX-9700 zinc oxide arrester tester is designed around accurate extraction of resistive current, helping maintenance personnel quickly assess arrester health on site. The following explains what to consider during selection and use from four aspects: parameter verification, synchronization method selection, operating points, and data management.
When selecting the model, first verify power supply and storage capacity. The instrument is powered by a built-in lithium battery and provides continuous operation for no less than 6 hours, covering the single inspection needs of most substations; storage capacity can save no fewer than 200 test records for later comparison. The operating environment range is -10°C to 50°C and humidity no greater than 85%RH; before on-site use, confirm that environmental conditions are within this range.
Calculation of resistive current depends on a voltage phase reference. The instrument supports multiple synchronization methods: taking three-phase or phase B voltage from the PT secondary side, suitable for occasions where voltage terminals are available; using an induction plate to pick up electric field strength, suitable for sites where direct voltage acquisition is inconvenient; and a no-voltage software simulation mode that provides reference results when no voltage signal is connected. Maintenance personnel should choose the appropriate method according to site conditions and pay attention to the reliability of synchronization signal wiring.
Before testing, confirm that the arrester surface is clean and leads are securely connected to avoid errors introduced by contact resistance. During testing, observe changes in the ratio of resistive current to total current and compare longitudinally with historical data; if a single measurement result is abnormal, repeat the test and check whether the synchronization method is appropriate. The instrument automatically records test data, which can be viewed on site.
After each test, it is recommended to save the data in association with the equipment ledger; storage space for more than 200 records can meet the record needs of one maintenance cycle. When comparing, focus on resistive current trends under the same voltage reference and avoid directly mixing data from different synchronization methods. Long-term tracking helps identify signs of valve element moisture ingress or aging.
