At the site of live testing for zinc oxide surge arresters, operation and maintenance personnel sometimes encounter inconsistent results from two consecutive measurements of the same phase arrester. A high resistive current reading or poor repeatability is often related to the wiring method of the test circuit and the control of the voltage boost process, rather than a change in the performance of the arrester itself. When using the YHX-5A zinc oxide surge arrester tester, understanding its working principle and standardizing operation help improve data credibility.
Key Measurement Points from the Perspective of Working Principle
Under power-frequency voltage, a normally operating zinc oxide surge arrester mainly conducts capacitive current, while the resistive current component is very small. The zinc oxide surge arrester tester synchronously collects voltage and current signals, separates the fundamental resistive current and its harmonic components, and thereby determines whether the arrester is internally damp, aged, or has degraded valve discs. Because the resistive current value itself is small, any poor contact or phase deviation may cause a noticeable shift in the reading. Therefore, the voltage sampling line of the test circuit must be reliably connected to the test object. Excessive contact resistance will directly affect the accurate acquisition of voltage phase and amplitude, causing distortion in the calculated resistive current result.
Effect of Voltage Boost Rate on Readings
The YHX-5A supports setting the voltage rise rate as needed during testing. If the voltage is raised too quickly on site, the transient response of the arrester valve disc capacitive current and resistive current has not yet stabilized, and the data collected by the instrument may be high, especially in test items that require recording reference voltage and leakage current. Operation and maintenance personnel should set the voltage boost rate within an appropriate range according to the voltage level of the test object and on-site conditions, and record after the reading stabilizes. For arresters of the same batch or the same installation location, it is recommended to maintain a consistent voltage boost rate so that historical data are comparable.
Wiring and On-Site Interference Troubleshooting Habits
A secure connection of the voltage sampling line is a basic requirement, but interference is often introduced on site due to oxidized clamps, suspended and swinging lead wires, or poor grounding. Before testing, operation and maintenance personnel can check whether the shielding layer of the sampling line is grounded at one end, whether the routing is away from high-current busbars, and confirm that the reference voltage signal is taken from the same system. If abnormal data are found, first disconnect the test object, observe the instrument background noise, and then gradually restore the wiring to locate the source of interference. Developing the operating sequence of first verifying wiring, then boosting voltage, and then reading can reduce the workload of repeated testing.
Data Recording and Comparison Methods
Each test should record ambient temperature, humidity, system voltage, and the voltage boost rate set on the instrument. Operation and maintenance personnel can compare the current resistive current with the previous data for the same phase, and if the change exceeds an empirical threshold, further confirm it in combination with infrared temperature measurement or an outage test. For testers such as the YHX-5A, properly saving the original waveform and the separated resistive current curve helps distinguish in subsequent analysis whether it is a change in arrester performance or a difference in test conditions. Data comparability depends on operational consistency, rather than simply pursuing the level of a single reading.
