Radio Frequency Coils

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Rogowski coils can also be used for rf current pulses and continuous wave current measurements up to several hundred MHz. These coils are ‘self integrating’ and do not need a separate integrator. They are used direct into a 50W input.
Radio Frequency Current Transducers:

These are widely used in the power industry and are commonly referred to as Rogowski Coils. The transducers are based on the air-cored Rogowski coil principle but with self-integration when the coil is correctly terminated. Thus they are not subject to the usual limitations of saturation and non-linearity of the wide-band ferrite current transformers.

They are primarily designed for use in measuring high-frequency current pulses in the presence of large power-frequency currents such as those generated by electrical discharge processes on high-voltage plant. The main application has been condition monitoring for partial discharges on large generators and motors but they have found many other applications. Besides detecting partial discharges the signal produced can be used to diagnose other plant problems such as diode failure in excitation systems.

The standard range of transducers has apertures of 200mm, 160mm, 120mm, 100mm, 70mm and 50mm. We can provide other sizes if required although this range should cover most applications.

Typical rise time: <3ns
Low-frequency limit: 100kHz
50Hz rejection : 96db
Sensitivity 0.1V/A

  RF Transducers 

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Ferrite Current Transducers:

These have apertures of 5mm and 15mm. Applications in the HV testing field include: isolated interfaces for capacitance couplers, matching units for blocking capacitors in discharge testing and in EMC testing.

Typical rise-time (10% - 90%): 3nS
Low frequency limit: 2.5kHz to 100kHz depending on the type
Sensitivity: 1mV/mA or 10mV/mA
Maximum continuous rf current: 0.5A - 5A depending on the type  

 Discharge Monitoring Equipment:

A range of instruments suitable for discharge monitoring using these coils is also available.

Small Aperture  R.F Transducers  pdf file: 220kB
Medium Aperture R.F. Transducers  pdf file: 108kB
R.F. Current Transducers Rogowski Coil Type  pdf file: 167kB
Discharge Processor System for Monitoring Partial Discharges in HV Plant.  pdf file: 195kB
Radio Frequency Current Transducer, Open Wand Type pdf file: 93kB

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