What are the main differences between Rogowski coil and current transformer?

Rogowski coil, also known as Rogwski coil in English, is hollow, that is, it has no solid core. It can be considered as applying the basic Faraday's law of electromagnetic induction to directly generate a voltage signal on the secondary side. The advantage of Rogowski coil relative to ordinary current transformers is that because it has no dead center, there is no dead center saturation phenomenon, and it can directly measure large currents. However, precisely because it has no dead center, the voltage signal induced by the Rogowski coil is very small compared to CT, and it is very easy to be affected by the stray magnetic field of the external environment, so the requirements for the winding process are very high. In addition, the voltage signal induced by the Rogowski coil cannot be used directly as a current signal. It must be differentiated to restore the current signal you want.

Application of Rogowski coil and current transformer: At present, Rogowski coil is only used in places with extremely large currents. Ordinary metering instruments use CT. Current transformer CT (current transformer) uses the principle of transformer. Generally, the large current on the primary side is converted into a small current on the secondary side, and then input to ADC for sampling after I/V conversion.

The main differences between Rogowski coil and current transformer 1. Different properties 1. Rogowski coil: It is a toroidal coil evenly wound on non-ferromagnetic materials. 2. Current transformer: It is an instrument that converts a large current on the primary side into a small current on the secondary side for measurement based on the principle of electromagnetic induction. 2. Different structures 1. Rogowski coil: It does not contain ferromagnetic materials, has no hysteresis effect, and has almost zero phase error; there is no magnetic saturation phenomenon, so the measurement range can be from several amperes to hundreds of kiloamperes; the structure is simple, and there is no direct circuit connection with the measured current; the response bandwidth is 0.1Hz-1MHz. 2. Current transformer: The current transformer is composed of a closed solid and winding. Its primary side winding has very few turns and is connected in series in the circuit of the current to be measured.

Design principle of the amplification and integration circuit of the Rogowski coil: The theoretical basis for measuring current with the Rogowski coil is Faraday's law of electromagnetic induction and Ampere's loop law. When the measured current passes through the center of the Rogowski coil along the axis, a corresponding changing magnetic field is generated in the volume surrounded by the toroidal winding.

If you want to accurately restore the measured AC current, you must add an inverting integration circuit. Because the voltage induced by the Rogowski coil is very small, in order to amplify the induced voltage, you must add an amplifier circuit in front of the integrator. Integration is a very important link. The restored signal is very small. For the convenience of measurement, the signal is amplified and then integrated. This can increase the restored signal on the one hand, and on the other hand, the presence of the capacitor can filter out unnecessary interference.