Rogowski Coils: Operating Limits  {short description of image}
The graph below illustrates the enormous range of currents and frequencies that can be measured using Rogowski coils.The limits shown are given as a guide only and it is sometimes possible to design a special system for operating outside the limits.

Upper limits:
The direct output from the coil depends on the rate of change of current.  For sufficiently high currents and frequencies the output can be large enough to cause a voltage breakdown.  Coils with a low mutual inductance are best for high currents and frequencies.

Resonance Limits:
Every coil has a self-resonant frequency caused by its self-inductance and inter-turn capacitance. The resonance also depencs on other factors such as cable capacitance. The resonance can be controlled by suitable damping circuitry, but generally it is not practicable to use a coil above its resonant frequency. The limits are shown by the vertical broken lines. See separate page for special High Frequency Coils.

Coil Operating Lomits Graph

Lower Limits:
At low currents and low frequencies the direct output from the coil is very low and the usefulness of the current transducer is limited by noise effects. Rigid coils which have a large mutual inductance are best for very low current measurements. The low current limit can be extended by using multiple primary turns round the coil or in the case of a flexible coil by wrapping the coil several times round the conductor. Electronic methods of signal recovery such as filters or phase-sensitive detectors are also useful.  

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