Views:2 Author:Site Editor Publish Time: 2020-11-14 Origin:Site
When purchasing film capacitors, the characteristic parameters of the capacitor are the key. So what are the characteristic parameters of film capacitors?
①Nominal capacity: The nominal capacity is the capacity marked on the capacitor. Allowable deviation: the allowable large deviation range between the actual capacitance and the nominal capacitance. Generally divided into 3 levels: I level ±5%, II level ±10%, III level ±20%. In some cases, there is still level 0 with an error of ±20%.
②Rated working voltage: The rated working voltage refers to the large DC or AC voltage that can be continuously applied to the capacitor without damaging the capacitor within the specified temperature range. It can also be regarded as the large DC voltage that the capacitor can withstand in the circuit for long-term stable and reliable operation, also known as withstand voltage. For devices with the same structure, medium, and capacity, the higher the withstand voltage, the larger the volume.
③Leakage current: This is the specific specification of electrolytic capacitors. Generally, after the capacitor is pressurized by the rated voltage of 3 Min, the ammeter is connected in series to test, and the leakage current must be 0.01CV (the product of uF capacitance value and rated voltage) or 3uA Below (whichever is greater). For specific low leakage current use, the leakage current must be below 0.002CV or 0.4uA.
④Temperature range: plastic film capacitor is -40℃ to +85℃. Ceramic capacitor T/C type is -40℃ to +85℃, Hi-K type and S/C type are -25℃ to +85℃.
⑤Dielectric loss: under the action of an electric field, the energy consumed by the capacitor in a unit of time by heating. These losses mainly come from dielectric loss and metal loss. Usually expressed by the loss tangent value. It is equivalent to the ratio of series equivalent resistance to capacitive reactance 1/wC.
The above are the characteristic parameters of film capacitors. On the basis of these characteristics, the huge advantages of film capacitors are presented. Especially its nominal capacity and temperature range of use are very important.