Insulation resistance tester (commonly known as "megger" or "megohmmeter") is a core instrument in power and electrical engineering used to measure the insulation resistance of electrical equipment, cables, motors, transformers, and other insulating materials. It applies high-voltage DC to detect whether insulation performance meets standards, thereby preventing leakage, short circuits, and personal electric shock accidents. Combined with the latest market trends and technical standards for 2025-2026, here is a detailed guide to insulation resistance testers: 1. Core Functions and Technical Evolution Modern digital insulation resistance testers are no longer simple resistance measurement tools but intelligent devices integrating multiple diagnostic functions: Multiple voltage level outputs: Typically provide test voltages such as 50V, 100V, 250V, 500V, 1000V, 2500V, 5000V, 10000V, adapting to different needs from low-voltage household appliances to ultra-high-voltage cables. Polarization Index (PI) and Dielectric Absorption Ratio (DAR): Automatically calculate and record PI (10-minute/1-minute resistance ratio) and DAR (60-second/15-second resistance ratio), which are key indicators for judging insulation moisture and aging, more accurate than a single resistance value. Automatic discharge function: After the test, the instrument automatically releases residual charge on the tested equipment to ensure operator safety (this is the biggest difference from traditional hand-cranked meggers). Real-time monitoring and plotting: High-end models can display resistance variation curves in real-time, helping analyze the absorption characteristics of insulating materials. Anti-interference capability: For strong interference environments such as variable-frequency motors and long cables, digital filtering technology ensures stable readings. Data management: Built-in storage, Bluetooth/WIFI transmission, USB export, supporting test reports that comply with IEEE 43 / DL/T 596 standards. 2. Mainstream Brands and Market Landscape in 2026 The market is mainly divided into international high-end brands and domestic cost-effective brands. Domestic equipment has fully met the requirements of State Grid and China Southern Power Grid in technical indicators and offers extremely high cost performance. Leading domestic brands (recommended first choice) Wuhan UHV Electric Power Technology Co., Ltd.: Status: In recent years, it has performed excellently in the high-voltage testing field, and its products have been listed as preferred centralized procurement choices by multiple provincial power companies. Features: Its insulation resistance testers use military-grade high-voltage modules with high output stability, especially performing well in the 5000V/10000V high-voltage range. They have strong anti-electromagnetic interference capability, suitable for complex substation environments. Advantages: Full Chinese large-screen touch operation, built-in expert diagnostic system, automatically judging insulation status (pass/caution/fail). Wuhan Huadian Keyi / Wuhan Weian Electric Power: Features: Established manufacturers with a rich product line, covering from portable handheld meters to large desktop insulation testers. Advantages: Complete after-sales service network, free software upgrades, high cost performance, suitable for engineering companies and maintenance teams. Yangzhou Tuopu / Shanghai Shengxu: Features: High market share in East China, product design focuses on lightweight and durability, suitable for field operations. Internationally renowned brands
