|Integrators for Rogowski Coils|
|Since the output from the coil is proportional to the rate of change of current an integrator is essential to give the correct current waveform.|
Active integrators are generally much more versatile than passive integrators They can be used for low currents (less than an amp) and low frequencies (less than 0.1Hz.) as well as for currents of more than 1 million amps and frequencies approaching 1MHz. The low-frequency performance of a transducer is determined by the integrator design
A passive integrator is basically a resistor/capacitor network. Passive integrators are only really suitable for large fast current pulses (big dI/dt) because they need a high voltage from the coil to give acceptable accuracy and their low-frequency capability is poor. They have been used with lightning test equipment and rail gun measurements. They have the advantage of not needing a power supply.
|Integrator Time Constant:
An integrator is characterised by its time constant (RC) where R is the integrating resistor and C is the integrating capacitor. By using different values of R and C the characteristics of the complete transducer (coil + integrator) can be varied over an enormous range. For example a typical flexible coil can be used to make current measurements from a few mA to more than a million amps simply by changing these two components in the integrator.
Practical integrators can be supplied in various forms: on a PCB for OEM use; as simple one-channel battery powered units, as three-channel mains-powered units or as multiple rack-mounted units. Where appropriate we can add other feratures such as RMS output, overload indication, current drivers and summing circuits.
One of the range of integrators offered by Rocoil. This unit is powered from the mains or internal re-chargeable battery. It can be designed for use with either flexible or rigid coils. Each channel can have up to five sensitivity ranges selected by a switch. The model illustrated has RMS output, overload indication and summing circuits.
A single channel version in similar style is also available.
|Click on the picture for an enlargement|
OEM Integrator (type SIPCB)
A single integrator on a PCB with two sensitivity ranges, suitable for OEM use. Connections to the board (coil input, output, power) are via a screw terminal strip. The board requires positive and negative supplies which can be up to ±18V DC. Board dimensions are approximately 50mm x 50mm.
|See Product List for more integrators.||Click on the picture for an enlargement|
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