Rogowski coil current transformers are widely used in high - frequency applications due to their unique advantages. Here is a detailed introduction:
Rogowski coils work by sensing the magnetic field in the space around the conductor. According to Ampere's law, there is a certain relationship between the current flowing through the conductor and the magnetic field around it. The Rogowski coil consists of an enameled wire evenly wound on a ceramic or other non - ferromagnetic frame with a differential permeability close to that of air. When a single - turn coil is placed perpendicular to this magnetic field so that the magnetic flux lines can link the coil, a voltage will be generated according to Faraday's law. The output voltage of the Rogowski coil is proportional to the rate of change of the measured current (di/dt). Therefore, it responds to the change in current. Through an external or integrated integrator circuit, the original current waveform can be restored.
Wide Bandwidth: Rogowski coil current transformers have a wide bandwidth that can range from a few Hz to several MHz1. This enables them to accurately capture high - frequency current waveforms, such as those containing high - order harmonics in power systems, with frequencies reaching dozens of kHz or even MHz1.
No Magnetic Saturation: Since they are air - cored coils without a magnetic core, there is no problem of magnetic saturation1. This is particularly important in high - frequency applications where the current may have large - amplitude fluctuations or high - peak values. For example, when measuring pulse currents with extremely fast rise times (nanosecond - level) and high - peak values in pulsed power technology, the non - saturation characteristic of Rogowski coils ensures accurate measurement1.
Good Linearity: They exhibit good linearity within their working range, which means that the output signal has a high - degree of linearity with respect to the input current. This is beneficial for accurately measuring high - frequency currents and enables precise analysis of the waveform and amplitude of high - frequency signals.
Good Phase Response: Rogowski coils have a small and stable phase shift within the effective bandwidth1. For applications that require accurate measurement of phase - related quantities, such as power factor, reactive power, and harmonic phase angle in advanced power quality analysis and metering, the good phase response of Rogowski coils is of great value1.
Power Quality Analysis1: In the monitoring and analysis of power quality issues in power grids or loads, such as harmonics, inter - harmonics, voltage sags/swells, and transients, sensors that can cover a wide frequency range are required. Rogowski coil current transformers can accurately measure these high - frequency components, providing important data support for power quality analysis.
Pulse Power Technology1: As mentioned earlier, they are suitable for measuring pulse currents with extremely fast rise times and high - peak values in pulse power technology, such as discharge currents and laser - driving currents. Their wide bandwidth and fast response characteristics allow for accurate capture of the transient processes of these pulse currents.
Short - Circuit Fault Current Measurement1: In power systems, when measuring fault currents that can reach hundreds of kilo - amperes, the non - saturation characteristic of Rogowski coils ensures the accuracy of measurement data during fault periods. This is crucial for the correct operation of protection devices and the analysis of fault characteristics.
High - Frequency Current Monitoring in Electronic Devices: In some electronic devices, such as high - frequency inverters, switching power supplies, etc., the operating current contains high - frequency components. Rogowski coil current transformers can be used to monitor these high - frequency currents to understand the operating status of the devices and conduct performance optimization and fault diagnosis.
