Flexible rogowski coil – NRC series – 1000A to 6000A

What is a Rogowski coil?

Rogowski coils have been used for the detection and measurement of electric currents. They are based on a simple principle: an “air-cored” coil is placed around the conductor in a toroidal fashion and the magnetic field produced by the current induces a voltage in the coil. The voltage output is proportional to the rate of change of current. This voltage is integrated, thus producing an output proportional to the current. By using precision winding techniques, especially developed for the purpose, the coils are manufactured so that their output is not influenced by the position of the conductor within the toroid, and to reject interference from external magnetic fields caused, for example, from nearby conductors. Basically, a Rogowski coil current measuring system consists of a combination of a coil and conditioning electronics.

They can be used in similar circumstances to CTs (current transformers) but for many applications they have considerable advantages:

• Wide dynamic range.
• High linearity.
• Very useful with large size or awkward shaped conductors or in places with limited access.
• Thanks to the structure without hard core, the coil can be easily manufactured according to the application or to the available space.
• Unlike traditional current transducers, there is no danger from open-circuited secondaries.
• They cannot be damaged by large overloads.
• They are non-intrusive.
• They draw no power from the main circuit carrying the current to be measured.
• They are also light weight and in some applications are light enough to be suspended on the conductor being measured.