Radiofrequency 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.

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  
  5mm Ferrite Transducer 

Radio Frequency Current Transducers:

These are primarily designed for use in measuring high-frequency current pulses such as those generated by electrical discharge processes. As the transducers are based on an air-cored principle they are not subject to the usual limitations of saturation and non-linearity of the wide-band ferrite current transformers. Thus they can be used to measure rf current signals and reject low-frequency currents when installed on cables and bus-bars carrying large power frequency currents.

Two preferred designs are provided. One is a closed ring that can be used in systems where it is possible to break the circuit to install the transducer. The second is a split ring type which is hinged and has a clasp and can be fitted without breaking the circuit. The addition of a splitting mechanism increases costs and reduces the specification and should only be considered where it is necessary.

The standard transducers have apertures 200mm, 160mm, 100mm, 70mm. We can provide other sizes if required.

Typical rise-time: <3nS
Low-frequency limit: 100kHz
50Hz rejection: 96dB
Sensitivity: 0.1V/A
Maximum continuous rf current: 40A

The transducers are assembled in aluminium cases which should be earthed to the plant at the point of installation. It is the installers responsibility to provide the insulation necessary for the operating voltage of the system on which it is installed. In many applications it is possible to install the transducers in terminal boxes of the plant under test.

Discharge Monitoring Equipment:

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

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