A Rogowski coil is a flexible air‑core current‑sensing device widely applied for measuring alternating current and transient impulse current in power electronics, power grids and industrial testing. Compared with traditional current transformers with iron cores, it possesses multiple prominent advantages, making it a preferred choice in numerous modern measurement scenarios.
First of all, Rogowski coils feature excellent linearity over a broad current range. Without ferromagnetic core materials, they avoid magnetic saturation problems that trouble conventional iron‑core current transformers. Even when measuring extremely large currents ranging from several hundred amperes up to hundreds of kiloamperes, the output signal maintains a proportional relationship with the measured current. This outstanding linear performance guarantees reliable measurement results whether for small working current or huge short‑circuit fault current. There is no risk of measurement distortion caused by core saturation during sudden current surges.
Secondly, its flexible and lightweight structure brings great installation convenience. Most Rogowski coils can be bent and opened, so operators do not need to disconnect primary conductors during on‑site installation. Users can directly wrap the coil around busbars, power cables or equipment terminals. Such non‑intrusive installation saves much downtime for power equipment. In compact power cabinets and narrow industrial spaces where heavy iron‑core transformers cannot fit, slim Rogowski coils can complete current sensing without modifying existing wiring layouts.
Thirdly, Rogowski coils deliver good safety performance. Since there is no iron core, dangerous high open‑circuit voltage will not occur at the secondary side, even if the signal processing circuit gets disconnected. For traditional current transformers, secondary open‑circuit may generate lethal high voltage and burn equipment, which poses major hidden risks for field staff. This characteristic greatly lowers safety hazards during commissioning, maintenance and long‑term running.
Moreover, it has a wide frequency response. It can accurately capture power‑frequency alternating current, high‑frequency harmonic current and fast transient impulse current. Traditional current transformers usually show poor performance under high‑frequency conditions. Rogowski coils work well across low power frequency up to megahertz‑level signals, suitable for harmonic monitoring, partial‑discharge testing and power‑electronic device waveform analysis.
Nevertheless, Rogowski coils require external integrator circuits to convert induced voltage into usable current signals, and they cannot measure pure direct current. Even so, their merits including no saturation, easy mounting, high safety and wide frequency band satisfy growing demands of smart power systems and industrial measurement. For AC and transient‑current measurement tasks, they provide a practical, cost‑effective sensing solution.
