How does a Rogowski Coil Work?

Rogowski coils work on the principle of faraday’s law. It is similar to AC current transformers (CTs). In current transformers, the voltage induced in a secondary coil is proportional to the current flow through the conductor.

The difference between Rogowski coils and AC current transformers is in the core. In Rogowski coils, an air core is used and in the current transformer, a steel core is used.

When current passes through the conductor, it will create a magnetic field. Due to an intersection with a magnetic field, a voltage is induced between the terminals of the Rogowski coil.

The magnitude of voltage is proportional to the current passes through the conductor. Rogowski coils are close pathed. Generally, the output of Rogowski coils is connected with the integrator circuit. So, the coil voltage is then integrated to provide an output voltage that is proportional to the input current signal.

Rogowski Coil Current Sensor

Rogowski coil current sensors are preferred due to no magnetic saturation, no overheating, or no hysteresis loss. As such there are very low magnetic losses in Rogowski coils. And it has very low insertion impedance.

It is able to sense the current flowing through the conductor. Hence Rogowski coils can also function as current sensors.

Rogowski coils are an air-cored toroidal winding wrapped on a conductor. For large currents, the output does not saturate due to the non-magnetic core.

It can be designed for a wide range of current measurements as well as protection applications. Rogowski coil sensor converts the input current to an output voltage. And it can sense the current flowing the conductor by integrating the output voltage.

There are two types of Rogowski coils; Rigid and Flexible.