Accoring to 62391-1© IEC:2006(E) ,This method is suitable for low esr capacitor (capacitors with relatively low internal resistance), and can be used as a shortcut method to reduce the measuring time .
The mesuring system includes the components in figure B.1. The system that replaces this method for measuring capacitance at low frequency may be used.
- Generate a sinusoidal voltage at the specified frequency with a frequency response analyzer and apply the voltage to a capacitor via a potentiostat;
- Detect the current that folws through the capacitor with a potentiostat (a device to automatically keep the electrode potential constant), and convert it into a voltage value to return it to the frequency analyzer.
- Obtain the impendance[Z]and phase angle Φ from the voltage and current of the capacitor to be measured.
Calculation of capacitance
- Calculate the reactance X by the following formula:
X is reactance(Ω)
[Z] is impedance (Ω)
Φ is the phase angle
- Use the calculated reactance to calculate the capacitance C of the capacitor by the follwing formula:
C is capacitance (F);
π is the circle ratio;
f is the measuring frequency(Hz)
- Use any measuring frequency from 0.05Hz,0.1 Hz,1 Hz,10 Hz or 100 Hz.
- The measuring voltage shall be 3% or less of the rated voltage;
- The basis voltage shall be 50% to 95% of the rated voltage. If no doubt arises on judgment, bias voltage may be omitted.
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