At substation preventive testing sites, crews often face a trade-off between two approaches: one is to remove the arrester and send it for inspection, and the other is to measure on site with a portable instrument while energized or de-energized. The former involves long outage time and many disassembly steps, while the latter places higher demands on instrument stability in strong electric field environments. The ZX-MOA860 zinc oxide arrester tester is designed for the latter operating conditions, with emphasis on on-site measurement and data retention.
The instrument is used to measure parameters of zinc oxide arresters such as total current, resistive current, and reference voltage. Through synchronized acquisition of voltage sampling and current sampling, it separates capacitive and resistive components to assist in judging moisture ingress, aging, and degradation trends of the valve elements. It supports both energized measurement and de-energized measurement modes, which can be selected on site according to the operating mode and safety measures. The instrument is equipped with an induction plate synchronization method. When it is not possible to connect to the secondary signal of a voltage transformer, the induction plate can be used to obtain a phase reference, reducing wiring workload.
Difficulties in on-site testing mostly come from power-frequency interference and harmonic components from nearby energized equipment. The instrument has a filtering stage at the sampling front end and supports averaging over multiple measurements to reduce reading fluctuations. The operation interface arranges parameter settings, sampling, and result viewing in sequence according to the test workflow, reducing the possibility of incorrect parameter settings. Power is supplied by a built-in lithium battery and is compatible with an external power source, facilitating long uninterrupted testing. Data can be stored locally and exported, making it convenient for engineers to archive and compare historical data.
The total current measurement range covers common on-site arrester specifications; the resistive current resolution is on the order of 0.01 mA, meeting the resolution requirements of preventive testing; the reference voltage measurement range is configured according to on-site operating voltage levels. Test accuracy is calibrated according to the conditions of on-site preventive testing use, and repeatability meets the consistency requirements for multiple measurements in the same bay. Specific range settings and error limits are subject to the accompanying technical documents.
When comparing and selecting, technical engineers can focus on three points: first, the method of obtaining the phase reference, i.e., whether it supports both PT sampling and induction plate synchronization; second, anti-interference measures, including whether the filtering method and averaging strategy are configurable; third, data management, i.e., whether it supports grouped storage and export by equipment number. The ZX-MOA860 provides options in both synchronization methods and data storage, making it suitable for crews that need to accumulate arrester operating data over the long term.
Before measurement, confirm that the arrester grounding down-conductor is reliably connected and that the sampling circuit wiring is secure; during energized measurement, set safety distances and assign supervisory personnel in accordance with on-site safety regulations. Test results are affected by ambient humidity and surface leakage. When necessary, clean the porcelain bushing surface and compare trends across multiple measurements rather than interpreting a single reading.
