The deterioration of zinc oxide arresters often begins with changes in the nonlinear coefficient of the valve discs. Looking only at U1mA or only at full current can easily lead to missed judgments. The YHX-5A synchronously collects leakage current during the voltage rise process. The starting action voltage U1mA measurement range is 0–1999V, and the full current measurement range is 1mA–10mA (expandable). It also records the resistive current component at 0.75U1mA. During testing, the voltage rise rate can be set as needed to avoid high readings caused by too rapid voltage rise.
The instrument uses differential input and digital filtering. In strong electric field environments of 220kV and below substations, the fluctuation of full current readings can be controlled within ±2% of the reading. The reference voltage channel supports both wired and wireless signal acquisition methods. In wireless mode, the reference end is isolated from the main unit, reducing errors introduced by ground potential differences. The test leads use a shielded coaxial structure. During on-site wiring, it is only necessary to clamp the reference voltage to the PT secondary side and connect the current end in series into the arrester grounding circuit.
The power supply method is a built-in lithium battery, with continuous working time of no less than 6 hours; the storage capacity can save no fewer than 200 sets of test records; the working temperature is -10℃–50℃, and the humidity is no greater than 85%RH. The equipment is suitable for routine testing, handover acceptance, and outage maintenance of zinc oxide arresters in substations, power plants, traction substations, and industrial and mining enterprise distribution systems. For ordinary valve-type, gapless, and series-gap arresters of voltage levels from 35kV to 500kV, U1mA and leakage current can be measured.
The instrument has a built-in clock, and each set of data is automatically attached with a time label. It supports vertical comparison of historical data for the same phase, and can also horizontally compare differences among three phases. When the change in U1mA exceeds ±5% of the initial value or the increase in full current exceeds 20%, the instrument gives a prompt, making it convenient for operation and maintenance personnel to make a comprehensive judgment in combination with the outage test report.
