The main characteristics of capacitors:
(1) capacitance and tolerance: the actual capacitance and the nominal capacitance of the maximum permissible deviation range. Generally divided into three: Level I ± 5%, II grade ± 10%, III grade ± 20%. In some cases, there are 0
Precision capacitor tolerance is small, and the error is large electrolytic capacitors, they use different tolerance levels.
Same common capacitor and resistor accuracy grade representation.
By letter: D - 005 - ± 0.5%; F - 01 - ± 1%; G - 02 - ± 2%; J - I - ± 5%; K- -II - ± 10%; M - III - ± 20%.
(2) Rated voltage: capacitor in a circuit capable of long-term stable, reliable work, to withstand the maximum DC voltage, also known as pressure. For the structure, the media, the same capacity of the device, the higher the pressure, the greater the volume.
(3) Temperature coefficient: within a certain temperature range, the temperature change per 1 ℃, the relative change in the value of capacitance. The temperature coefficient as small as possible.
(4) Insulation resistance: to indicate the size of the leakage. Generally small amounts of capacitance, insulation resistance is large, in the hundreds of megabytes or a few giga-ohm ohms. Electrolytic capacitor insulation resistance is generally small. Relatively speaking, the better the insulation resistance, leakage current is also small.
(5) Loss: under the action of an electric field, the capacitor in the unit time heat energy consumed. These losses are mainly from the dielectric loss and metal loss. Often used to represent the loss tangent.
(6) Frequency characteristic: the electrical parameters of the capacitor with the changing nature of the electric field frequency. Capacitor working at high frequencies, due to the dielectric constant at high frequencies than at low frequencies, capacity is reduced accordingly. Loss also increases with increasing frequency. In addition, work at high frequencies, the resistance distribution parameters of the capacitor, such as pole-chip resistors, lead and pole pieces between the pole pieces of the self-inductance, lead inductance, etc., will affect the performance of the capacitor. All of these, so that the capacitor of the frequency of use is limited.
