Pay attention to these parameters when purchasing capacitors

When purchasing products, it is impossible to see through the eyes whether the performance of the products, the materials used, and whether they meet their own needs, etc. Parameters can show the performance, material, life of this product, etc. Therefore, it is very important to select products by parameters. The same is true for capacitors. Pay attention to the following parameters when purchasing.

1. Nominal capacitance: the capacitance value determined by the capacitor design and usually marked on the capacitor.

2. Capacity deviation: the allowable deviation value of the nominal capacity.

3. Lower limit class temperature: low ambient temperature for continuous operation determined by capacitor design.

4. Upper class temperature: high ambient temperature for continuous operation determined by capacitor design.

5. Rated temperature: high ambient temperature at which rated voltage can be applied continuously.

6. Rated voltage: the peak value of large DC voltage or pulse voltage that can be continuously applied to the capacitor at any temperature between the lower class temperature and the rated temperature.

7. Class voltage: the high voltage that a capacitor can continuously apply to the capacitor at the upper class temperature.

8. Temperature derating voltage: a high voltage that can be continuously applied to a capacitor at any temperature between the rated temperature and the upper class temperature.

9. Climate category: the high voltage that can be continuously applied to the capacitor at any temperature between the temperature of the climate category to which the capacitor belongs. (iec60068-1 standard: such as 55 / 85 / 21). One number represents the lower category temperature, two represents the upper category temperature, and the third represents the number of days of steady-state heat and humidity.

10. Capacitor temperature coefficient: the rate of change of capacitance with temperature measured within the specified temperature range.

11. Loss tangent: at sinusoidal voltage of specified frequency, the loss power of capacitor divided by the reactive power of capacitor

12. Insulation resistance / time constant: the insulation resistance is the ratio of the DC voltage applied one minute after the capacitor is charged to the leakage current value flowing through the capacitor.

13. Pulse rise time: the pulse rise time indicates the capacity of the capacitor to withstand the high current peak generated by the rapid change of voltage.

14. Self healing: the process in which the electrical characteristics of a capacitor quickly and basically recover to the value before breakdown after the dielectric breakdown of the capacitor. (this is the performance of film capacitor)

Understand the basic meaning of the above capacitor parameters, and select the appropriate capacitor according to your own requirements.