What are the advantages and disadvantages of rogowski coil?

Advantages

This type of coil has advantages over other types of current transformers.

1. It is not a closed loop, because the second terminal is passed back through the center of the toroid core (commonly a plastic or rubber tube) and connected along the first terminal. This allows the coil to be open-ended and flexible, allowing it to be wrapped around a live conductor without disturbing it.

However, positioning of the measured conductor is important in that case: It has been shown that, with flexible sensors, the effect of the position on the accuracy ranges from 1 to 3%. Another technique uses two rigid winding halves with a precise locking mechanism.

2. Due to its low inductance, it can respond to fast-changing currents, down to several nanoseconds.

3. Because it has no iron core to saturate, it is highly linear even when subjected to large currents, such as those used in electric power transmission, welding, or pulsed power applications. This linearity also enables a high-current Rogowski coil to be calibrated using much smaller reference currents.

4. No danger of opening the secondary winding.

5. Lower construction costs.

6. Temperature compensation is simple.

7. For larger currents conventional current transformers require an increase of the number of secondary turns, in order to keep the output current constant. Therefore, a Rogowski coil for large current is smaller than an equivalent rating current transformer.

Disadvantages

This type of coil also has some disadvantages over other types of current transformers.

1. The output of the coil must be passed through an integrator circuit to obtain the current waveform. The integrator circuit requires power, typically 3 to 24Vdc, and many commercial sensors obtain this from batteries.

2. Traditional split-core current transformers do not require integrator circuits. The integrator is lossy, so the Rogowski coil does not have a response down to DC; neither does a conventional current transformer (see Néel effect coils for DC). However, they can measure very slow changing currents with frequency components down to 1 Hz and less.