In addition, direct contact between the elongated cathode aluminum foil and the capacitor aluminum casing is also a good way to reduce thermal resistance. At the same time, it should be noted that the aluminum case will be negatively charged and cannot be used for negative connection.

The capacitor must be installed correctly to reach its designed working life. For example: RIFAPEH169 series and PEH200 series should be installed vertically upwards or horizontally. At the same time, make sure that the safety valve is facing upwards, so that the hot electrolyte and vapor can be smoothly discharged from the safety valve when the capacitor fails.

When the capacitors are arranged very compactly, a space of at least 5mm should be left between adjacent capacitors to ensure proper air flow. When using bolts to install, the control of the nut torque is very important. If the screw is too loose, the capacitor and the heat sink cannot be in close contact; if it is screwed too tight, the thread may be damaged. At the same time, it should be noted that the capacitor should not be installed upside down, otherwise it may cause the bolt to break.

The capacitor should be installed as far away as possible from the heating element, otherwise the high temperature will shorten the service life of the capacitor, thus making the capacitor the shortest life component in the entire circuit. In the case of high ambient temperature, use forced air cooling as much as possible, and install the capacitor at the air inlet.

3. The influence of frequency

If the current is composed of the fundamental frequency and multiple harmonics, the power loss value generated by each harmonic must be calculated, and the calculation results must be added to obtain the total loss value.

In high frequency applications, the leads at both ends of the capacitor should be as short as possible to reduce the equivalent inductance.

The resonant frequency (fR) of a capacitor varies with the type of capacitor. For solder-blade and bolt-on aluminum electrolytic capacitors, the resonance frequency is between 1.5kHz and 150kHz. If the capacitor is used above the resonance frequency, the external characteristics will be inductive.

4 Conclusion

To sum up, in the case of avoiding abnormal failures, choosing the correct application conditions and environment, the life of the electrolytic capacitor can be guaranteed.