PASSIVE TRANSDUCERS (Lr) FOR HIGH FREQUENCY (MHz) SINUSOIDAL CURRENT WAVEFORMS |
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A Rogowski coil with passive Lr (also known as self) integration is suitable for measuring high frequency sinusoidal currents.
When might a Rogowski coil with Passive Lr integration be suitable?
- if the current is of the order of a few hundred kHz or greater, and the magnitude of the current causes the rms di/dt rating of the CWT range to be exceeded
- if the frequency of the sinewave is above the high frequency bandwidth of the CWT range.
provided
- the current is a largely undistorted sinewave (with no significant harmonic content)
- the experimental set-up is symmetrical i.e. the current goes through the centre of a circular Rogowski coil.
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What are the benefits of Lr integration?
o High
frequency 3dB bandwidths can be significantly higher than either active or
passive RC integration.
o Sinusoidal waveforms with a large rms di/dt can be
measured.
.and the drawbacks?
o At high
frequencies, above the 3dB bandwidth, the transducer can have significant
resonance. The coil is not terminated with its characteristic impedance thus the
response of a Rogowski coil with Lr integration is oscillatory. This is
particulary problematic when monitoring pulsed currents.
o The experimental
set-up needs to be as symmetrical as possible, or unwanted resonant effects will
distort the measurement.
o With no active integrator Lr integration has a severely limited low frequency bandwidth. 3dB cut-offs are typically in the kHz range. Lr integration is only suitable for measuring sinusoidal waveforms of a few hundred kHz and above.
If you think that your current lies outside the capabilities of our standard ranges, please Contact
Us giving as much information about your requirement as possible and we will
be happy to investigate the possibility of a special design. |
