Parameters to pay attention to when purchasing capacitors

When purchasing capacitor products, you can only see the appearance with your eyes. It is impossible to know the performance of the product, the materials used, and whether it meets its own needs. At this time, you need to look at the parameters, which can indicate the performance, materials, and life of the product. Therefore, be sure to 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: Allowable deviation of nominal capacitance.

3. Lower limit category temperature: Low ambient temperature determined by capacitor design for continuous operation.

4. Upper category temperature: High ambient temperature determined by capacitor design for continuous operation.

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

6. Rated voltage: At any temperature between the lower limit category temperature and the rated temperature, the peak value of a large DC voltage or pulse voltage that can be continuously applied to the capacitor.

7. Category voltage: The high voltage that a capacitor can continuously apply to a capacitor at an upper category 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 category temperature.

9. Climatic category: The high voltage that can be continuously applied to the capacitor at any temperature between the climatic category temperature to which the capacitor belongs. (IEC60068-1 standard: such as 55/85/21). The first number represents the lower limit category temperature, the second number represents the upper limit category temperature, and the third number represents the number of days of steady-state damp heat.

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

11. Loss tangent: Divided by the sine voltage of the specified frequency, the capacitor's loss power is divided by the capacitor's reactive power.

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

13. Pulse rise time: The pulse rise time indicates the ability of the capacitor to withstand the large current peaks caused by rapid voltage changes.

14. Self-healing: The process in which the capacitor's electrical properties quickly and substantially recover to their previous values after the dielectric's local breakdown. (This is the performance of the film capacitor)

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