Tuesday, February 22, 2011
【 Weak current College 】 electrolytic capacitor of electrical parameters 】
Here the main means of electrolytic capacitors, Aluminum Electrolytic Capacitor, its basic electrical parameter includes the following five points:
1, capacitance value
Electrolytic Capacitor tolerance values, depending on the AC voltage work the impedance. Therefore capacity value, AC capacitor value, along with the working frequency, voltage, as well as the measurement method. The provisions in standard JISC5102: aluminum electrolytic capacitor capacitance measurement condition is in frequency as 120Hz, maximum AC voltage to voltage 0.5Vrms, DCbias 1.5 ~ 2.0V conditions. Can assert, aluminum electrolytic capacitor capacity increase of the frequency decreases.
2. loss angle tangent of δ T a n
The equivalent circuit in the capacitor, in tandem with the equivalent resistance ESR capacitance 1/C ratio called ω T a n δ, ESR is here at 120Hz calculated values obtained. Obviously, T a n δ with measuring frequency increases, the larger, with the measurement temperature decreases.
3, impedance Z
In the specific frequencies, impeding the AC current through a resistance which is the so-called impedance (Z). It and capacitance equivalent circuit of capacitance, inductance values are closely related, and are also related with ESR.
Type, XC = 1/ω C = 1/2 to π f C
Capacitor capacitance (XC) in the low frequency range as the frequency increases gradually to reduce the frequency, continue to increase reach medium frequency range reactance (XL) to ESR values. When the frequency reaches high frequency range inductive reactance (XL) becomes dominant, so the impedance is as the frequency increases.
4, leakage current
Capacitor's media on DC has great impediment. However, because the aluminum oxide film media soaked electrolyte, voltage, and fix again formation of oxide films will have a very small called leakage current of electricity. Generally, residual flows with temperature and voltage but increased.
5, ripple current and ripple voltage
In some of the information in both called "ripple currents" and the "ripple voltage" is actually ripplecurrent, ripplevoltage. Meaning is the capacitor can withstand ripple current/voltage values. They and the close relationship between ESR, you can use the following equation:
Type, Vrms said ripple voltage
Irms said ripple current
R represents a capacitor ESR
Top visible, when the ripple current increases, even in ESR remain unchanged, the ripple voltage will increase exponentially. In other words, when a ripple voltage increases, ripple current is increased, this is also called capacitor with lower ESR values. Fold to join the ripple current, because of the internal equivalent capacitance series resistance (ESR) cause the heat, thus affecting the life of the capacitor. General, ripple current proportional to the frequency, low frequency is also relatively low ripple current.