Selecting High-Frequency Rogowski Current Probes: IWATSU and PEM

Rogowski coils are mainly used for measurement of large AC currents (including pulsed and continuous signals).

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During selection, the following parameters mainly need to be clarified:

• Current range: the maximum measurable peak current of the sensor;

• Output transfer ratio/volts-per-ampere ratio: describes the correspondence between the measured current and the sensor output signal;

• Frequency range: describes the maximum measurable 3dB signal bandwidth of the sensor,Pulse measurement requires attention to the low-frequency cutoff frequency ；

• di/dt: the maximum measurable rate of change of the signal by the sensor; usually defined as the maximum steep-fall rate of the measured signal;

• Droop: the rate at which the sensor output droops when the measured signal does not change, usually expressed as the percentage of peak value droop per unit time. It and the sensor peak retention capability are opposing specifications;

• Coil length: the coil circumference is determined according to the diameter of the cable under test.

• Wire diameter: refers to the wire diameter thickness of the measuring coil itself; the wire diameter thickness is very important to the application range.

• Voltage withstand: refers to the voltage-withstand rating of the measuring coil; a higher voltage withstand rating is preferred.

• Temperature resistance: refers to the temperature range that the measuring coil can withstand; the optimal temperature range is -155 to 180 °C.

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** Compared with high-frequency pulsed current transformers, Rogowski coils have no magnetic saturation limitation.