DL/T 987-2005 "General Technical Conditions for Zinc Oxide Arrester Resistive Current Tester" sets clear requirements for the current measurement range, accuracy, and harmonic analysis capability of testers. In response to these requirements, the intelligent arrester characteristic tester has developed parameter design features that distinguish it from traditional solutions.
In terms of sampling methods, traditional solutions mostly rely on wired synchronization, requiring direct wiring from the PT secondary side to obtain the reference voltage, with an applicable distance usually not exceeding 40 m. The intelligent tester provides four modes: wired synchronization, wireless synchronization, induction plate sampling, and no-voltage simulation. Wireless synchronization transmits the PT signal through a module, with a distance of up to 1000–1500 m or more, making it suitable for outdoor or long-distance scenarios; induction plate sampling uses non-contact acquisition through electric field induction, with an electric field strength adaptation range of 30–300 kV/m, solving the detection needs under conditions where there is no PT wiring.
In terms of measurement capability, the tester covers a full current range of 0–20 mA. Resistive current, as the core criterion, can reflect the degree of valve disc aging and moisture ingress. It also supports capacitive current, 3rd–9th harmonics, power-frequency reference voltage, active power (0–8 W), and phase difference measurement. The voltage measurement range is 30 V–250 V, the current channel input resistance is no greater than 1–2 Ω, and the harmonic measurement accuracy is ±(5% reading + 10 μA).
Compared with basic similar solutions that only support single-phase measurement, this instrument supports simultaneous testing of three-phase current and three-phase voltage, completing ABC three-phase measurement with one wiring setup, and uses digital filtering and Fourier harmonic analysis to automatically compensate for inter-phase interference angles. In terms of safety design, the transformer completely isolates the tester from the on-site PT, and with dual protection from a 0.1 A fuse, it reduces the risk of damaging the PT due to misoperation. During selection, designers can weigh configurations such as standard type, split type, and handheld type according to substation distance, whether three-phase simultaneous testing is required, and data export needs.
