1. Metallized film capacitors will change their electrical characteristics with the ambient conditions in which they are placed. Even if the humidity in the air penetrates, the capacity will change slightly, and the degree of the capacity change will vary depending on the inductive material, the structure of the exterior material, etc.
2. Noise problem: The noise generated by the capacitor is due to the mechanical vibration of the thin film between the film diodes through the action of AC power, and the noise problem, especially when the voltage is unstable or has a voltage surge or is used at high frequencies, it will produce higher vibration sound, but it will not affect the electrical characteristics of the capacitor itself, and the volume and frequency of the noise will also change with different manufacturing batches. You must confirm the degree of audible and acceptable noise during use.
3. Storage method and storage conditions
( 1 ) Moisture, dust reactivity, acidifying gas (salted water, acidified water, sulfite gas) will have a deteriorating effect on the welding terminals of the external electrodes of the container, and the above problems must be paid attention to .
( 2 ) In particular, avoid places with high temperature and high humidity, store at -10~ + 40℃, humidity below 70 %, do not directly expose to water or water vapor , so as to avoid water vapor intrusion and damage the capacitor .
4. Problems that should be paid attention to when using
( 1 ) Capacitors must avoid the environment where the voltage and temperature changes rapidly, even if it does not exceed the rated value of the capacitor, it will cause rapid deterioration of the quality of the capacitor.
( 2 ) When the capacitor is used in the circuit, there is fast or frequent charge and discharge, special frequency such as high frequency or different atmospheric pressure, etc. The applicability of the capacitor must be confirmed.
( 3 ) During the capacitor withstand voltage test and life test, when multiple capacitors must be connected in parallel, the capacitor must be connected in series with a discharge resistance.
( 4 ) The capacitor is subjected to overvoltage, overtemperature abnormality or the end of the product life, resulting in damage to the insulating material , and the capacitor may be burned out by smoke. To prevent this from happening, a protective capacitor must be used to make the capacitor open circuit when abnormal conditions occur, to achieve the effect of protection .
5. If you see or smell smoke from the capacitor, disconnect the power supply immediately to avoid fire .
6. The specification of the capacitor is mainly based on the product specification. If it cannot be used with or exceeds the rated use, the scope of application must be redesigned .
7. The capacitor shell is a plastic product. Due to factors such as material shrinkage, the surface of the plastic shell is slightly sunken. It is not due to a problem with the manufacture of the capacitor and has nothing to do with electricity.
8. Reliability test standard : rated voltage × 1.25 ( 600 hours set temperature )
9. Definition of terms
( 1 ) Rated frequency: Capacitors are suitable for the specified frequency and conditions for which they are designed.
( 2 ) Rated voltage: The voltage that can be continuously applied between the terminals of the capacitor, and the voltage marked on the casing. Do not exceed this voltage during use, so as not to affect the life.
( 3 ) Rated capacity: The electrostatic capacity of the capacitor at room temperature, and the value marked on the shell, the unit is μF.
( 4 ) Rated current: Calculated value of rated frequency, rated capacity and rated voltage
Rated current=2π×(rated frequency)×(rated capacity)×(rated voltage)×10 - 6
( 5 ) Rated VA: Calculated value of rated frequency, rated capacity and rated voltage, the unit is VA,
Rated VA=2π×(rated frequency)×(rated capacity)×(rated voltage)×10 -6
( 6 ) Maximum allowable temperature: When the capacitor and the machine equipped with the capacitor are in normal operation, when the temperature reaches a stable level, the allowable temperature limit of the capacitor shell should not exceed this temperature, so as not to affect the performance of the capacitor.
( 7 ) Minimum allowable temperature: The lowest temperature around the capacitor without affecting the overvoltage.
( 8 ) Maximum allowable overvoltage: The overvoltage limit for the rated frequency at which the capacitor terminals are continuously applied without failure .
( 9 ) Maximum allowable overcurrent: The overcurrent limit that continuously flows between the terminals of the capacitor and does not cause a malfunction in practice
( 10 ) Maximum allowable VA: The maximum VA limit that the capacitor can be used continuously without failure in practice.
( 11 ) Loss rate: The ratio of capacitor loss rate (W) to capacitor VA value.
10. If there is no special instruction in the standard use state, the capacitor must be used in this range
( 1 ) Relative humidity: The relative humidity should not have condensation or condensation of water droplets.
( 2 ) High allowable overvoltage: The maximum allowable overvoltage is 110% of the rated voltage.
( 3 ) Maximum allowable overcurrent: The maximum allowable overcurrent is set at 130% of the rated current
( 4 ) Maximum permitted VA: The maximum allowable VA value is set at 135% of the rated VA.
( 5 ) Maximum allowable ambient temperature: The maximum allowable temperature of the capacitor is less than 10°C. For example, if the maximum allowable temperature of the capacitor is 70°C, the maximum allowable ambient temperature is 60°C.
