Rogowskikoil

Rogowskikoil is a non-contact current sensor based on the Rogowski coil principle. It employs a flexible, air‑housed coil that encircles a conductor carrying the current to be measured. Because it has no ferromagnetic core, the device offers a wide bandwidth and linear response over a broad frequency range, and it is well suited to measuring sharp transients and high currents without core saturation. The coil's output voltage is proportional to the time derivative of the enclosed current, V ∝ dI/dt. To obtain the actual current waveform I(t), the coil’s output is integrated by a signal processor or passive integrator; the resulting signal is then scaled by calibration constants determined by coil geometry and integration behavior. Rogowskikoil is inherently AC-coupled and cannot measure steady direct current without special arrangements.

The Rogowski coil was developed by Walter Rogowski in the early 20th century. Since then it has become a standard tool in electrical metrology, used for laboratory current measurements, relay testing, power electronics, and high-current diagnostics where magnetic cores are undesirable.

Advantages include wide dynamic range, minimal saturation, and easy installation around large conductors. Limitations include the need for a stable integration stage, sensitivity to external magnetic fields, and an absence of DC measurement capability.

See also: Rogowski coil, current sensor, electrical measurement.