The quality factor is a measure of the extent to which a capacitor acts like a theoretically pure capacitor. It is the inverse of the dissipation factor (DF). Q is typically reported for capacitance values ≦ 330pF, DF > 330pF.
Often multiple coils are necessary to adequately measure across the 0.5 ～ 330pF range. For capacitors > 330pF, the quality factor can be calculated by taking the inverse of the dissipation factor (see Formula 1). What is the allowable ripple current of capacitors?
The key to measure the capacitance and dissipation factor correctly is the meter settings. The voltage settings are critical for high capacitance capacitors. For some cap meters, the applied voltage to the test component is not enough and the capacitance reads low. The frequency settings are also important.
Therefore, Cs should be used for the meter setting to measure capacitance. A good rule of thumb to select the impedance setting is to use Cp for capacitor impedance values greater than 10kΩ and Cs for less than 10Ω. How can I accurately measure the quality factor (Q)?
For capacitors that are 10 μF or larger, a lower frequency of 120 Hz is used. Typically, a 1 kHz test frequency is used to measure inductors that are used audio and RF circuits. And a 120 Hz test frequency is used to measures inductors that are used for filter chokes in power supply.
The Q-factor or the quality factor of a capacitor at the operating frequency ω is defined as the ratio of the reactance of the capacitor to its series resistance. Q = (X C / R). It is a dimensionless quantity. D-Factor – The dissipation factor of a capacitor is the power loss when AC is applied through the capacitor.