Operating principle of Rogowski coil

Roche coil principle

Rogowski The coil is placed around the conductor “ Hollow core ” Ring coil . The alternating magnetic field produced by the current induces a voltage in the coil , The voltage is proportional to the rate of change of the current .

The direct output of the coil is controlled by Vout=M dI/dt give , among M Is the mutual inductance of the coil dI/dt Is the rate of change of the current . In order to complete the work of the transducer , Electronic integration of the voltage , So that the output of the integrator is a voltage that can accurately reproduce the current waveform .

chart ： coil + integrator

Coil and integrator

The combination of coils and an integrator provides an extremely diverse current measurement system , The system can be designed to accommodate a wide range of frequencies , Current level and conductor size . The output is frequency independent . It has accurate phase response , It can measure complex current waveform and transient .

linear ：

Rogowski One of the most important characteristics of coil measurement system is its inherent linearity . The coil does not contain a saturation component , And the output increases linearly in proportion to the current , Until the working limit determined by voltage breakdown is reached . The integrator is also inherently linear until the electronics are saturated . Linearity makes Rogowski The coil is easy to calibrate , Because the transducer can be calibrated at any convenient current level , And calibration for all currents （ Including very large current ） It's all accurate . and , Because of its linearity , The transducer has a very wide dynamic range and excellent transient response .

Coil winding ：

about Rogowski coil , It is important to ensure that the windings are as uniform as possible . The uneven winding makes the coil vulnerable to the magnetic attraction of adjacent conductors or other magnetic field sources . We have developed special machines for making precise windings . There are many types of coils , Including rigid and flexible coils , But we have also developed several other variants to meet specific needs . Output indication ：

The output of the integrator can be used for input impedance greater than 5kohm Any form of electronic indicating device , Such as voltmeter , Oscilloscope , Transient recorder or protection system .

Separate the coil ：

Some designs of coils can be mounted on conductors , Without disconnecting the conductor . Most flexible coils can be installed in this way , It can also manufacture split rigid coils . If the alignment error of the two halves is very small , Then shunt iron core equipment （ Such as current transformer ） Will suffer significant amplitude and phase errors . Roche coil has no such problem . The misalignment of the connecting surface of the separated Rogowski coil has little effect on the amplitude , It has no effect on the phase .