Rogowskikäämi

Rogowskikäämi, also known as a Rogowski coil, is a type of electrical device used for measuring alternating current (AC) and fast-changing transient currents. It consists of a flexible coil wound around a non-magnetic core, typically a plastic or fiberglass former. The key principle behind its operation is Faraday's law of induction. When an AC current flows through a conductor, it creates a changing magnetic field around it. The Rogowski coil encircles this conductor, and the changing magnetic field induces a voltage in the coil. This induced voltage is directly proportional to the rate of change of the current being measured.

To obtain an accurate measurement of the current itself, the induced voltage signal from the Rogowski coil must be integrated electronically. This integration process converts the rate of change of current back into a signal proportional to the current magnitude. Rogowski coils offer several advantages over traditional current transformers. They are non-intrusive, meaning they do not need to be inserted in series with the conductor being measured, making installation easier, especially for high-current applications or in situations where the circuit cannot be easily broken. They are also lightweight, flexible, and can be manufactured in various shapes and sizes to accommodate different conductor configurations. Furthermore, they have a wide dynamic range and can measure very high currents without saturation, unlike iron-core transformers. Their linear response across a broad frequency range makes them suitable for measuring complex waveforms and transient events. However, they require external integration circuitry, which adds to the overall system complexity and cost. Rogowski coils find applications in power monitoring, motor control, welding equipment, and fault detection.