subject: Aluminum Electrolytic Capacitor Parameters And Selection Skills Of A Detailed [print this page] Recently, some companies ask HC about aluminum electrolytic capacitor electronic network use and buy the issue, Xiao Bian special summary of related skills, for your reference:
Aluminum electrolytic capacitor is made of aluminum cylinder cathode, which is equipped with liquid electrolyte, insert a curved cathode made of aluminum do. Also need to address through the DC voltage to the positive electrode to form a layer of oxidation film to do media. It is characterized by large capacity, but the leakage large, poor stability, there are positive and negative polarity, suitable for power supply filtering or low-frequency circuits.
Capacity and rated voltage
Aluminum electrolytic capacitor body superscript some capacity and pressure, these two parameters is very important, is the most basic elements selected capacitor.
Selection of the actual capacitance of the current rapid pace of change in local capacity to use large capacitors, but not the capacity the better, first of all, capacity increases, cost and size may be increased, In addition, the greater the charge current on the capacitor The larger the longer the charging time will be. These are the practical application of selection to be considered.
Rated operating voltage: in the specified operating temperature range, long-term reliable capacitors work, it can withstand the maximum DC voltage. In AC circuits, should pay attention to the increase of AC voltage can not exceed the maximum working voltage of DC capacitor. Common fixed capacitor voltage are 6.3V, 10V, 16V, 25V, 50V, 63V, 100V, 250V, 400V, 500V, 630V. Capacitance in the circuit voltage can not actually be subject to pressure over its value.
In the filter circuit, the capacitor AC RMS voltage value is not less than 1.42 times. Also note that a problem is the issue of the operating voltage margin, generally to more than 15%.
Let the capacitor has a rated voltage of more margin, can reduce the internal resistance, lower leakage current, reduce the loss angle, increased life expectancy. Although, 48V 50V operating voltage aluminum electrolytic capacitors use a short time no problem, but with long, life is likely to reduce.
Dielectric loss
Capacitor in the electric field consume energy, usually loss of power and reactive power of capacitor ratio, that is, that the tangent of loss angle (in the capacitor's equivalent circuit, the equivalent resistance in series with the capacitance 1/ C of ESR than as Tan , where ESR is the value calculated under 120Hz. Obviously, Tanmeasuring frequency increases with the larger, with a decline in the increase of temperature measurement). The greater the loss angle, the greater the loss of the capacitor, the capacitor loss angle great work not suitable for high frequency cases. Dissipation factor dissipationfactor (DF) exist in all capacitors, sometimes to the loss angle DF value tansaid. This parameter is the smaller the better. However, this parameter is higher electrolytic capacitor.
DF value is high or low, on the same brand, same series of capacitors for temperature, capacity, voltage, frequency ... ... have a relationship; when the capacity of the same, the pressure the lower the value the higher the DF. In addition, the higher the temperature the higher the DF value, the higher the frequency the higher the DF values also.
Dimensions
Overall dimensions and weight and pin type associated. singleended is the radial lead type, screw the lock screw type, in addition to SMD aluminum electrolytic capacitors. As for weight, the same capacity with pressure, but the two capacitors of different brands compare, the weight must be different; while the shell shape and size more planning. In general, the same diameter, the same capacity capacitor, a high degree of low height and large capacitor can be alternative, but the length of alternative high and low capacitance is necessary to consider the issue of institutional interference.
ESR
A capacitor structure arising due to their various impedance, inductance.
