Brief introduction of polyester capacitors：It uses two sheets of metal foil as electrode, which was clipped in a thin insulating medium, and rolled into a cylindrical or flat column.Its medium is polyester. Polyester film capacitor, the dielectric constant is higher, the volume is small, the capacity is large, the stability is good, it is suitable to be used as bypass capacitor.
Advantage of polyester capacitors：The precision，loss angle, insulation resistance, temperature characteristic, reliability and adaptation environment indicators of polyester capacitors are better than electrolytic capacitor and ceramic capacitor.
Shortcoming of polyester capacitors：The volume of its capacity price ratio are larger than that of the above two kinds of capacitor.
Purpose of polyester capacitors：It is used in all kinds of DC or low frequency pulse circuit.
Parameter identification of polyester capacitors：In the foreign capacitor voltage value representation method, 2A indicated that the pressure is 1 * 10^2V=100V, for example the 823J indicated the capacity is 82000Pf, the J indicated the capacity to allow the deviation is + 5%.
2A823J that is 82000Pf + 5%, pressure 100V.
Parameter marking method of capacitor:
Direct labeling method: the capacitor of the main parameters (nominal capacity, rated voltage, and allowable deviation) directly marked on the capacitor, such as 0.0047 mu f/275V and 0.0047 u F is capacity, equivalent to 4700Pf, 275v pressure (not included in the preferred number series).
Character notation:The main parameters of the capacitor are labeled by digital or mixed method of letters and digits.
Digital marking method usually use 3 digits indicate the capacity of the capacitor.Among them, the first two are the effective number, the third is the multiplier (that is, the value of the effective value of 0). As 104, it indicates that the valid value is 10, plus four 0 in the back of it, that is, 100000Pf=0.1 F.
Letters and numbers mixed method: with 4 - 2 digits to indicate the effective value, with P, N, M, G,, m and other letters of the number of the number of the following. The import capacitor does not use the decimal point when it is marked, but writes the integer part to the letter before the decimal part is written in the back of the letter. Such as 4P7 said 4.7Pf, 3m3 said 3300 F, etc..