[Explanation of the cause of capacitor failure] It failed due to excessive ripple, and the electrolyte was ejected.
Please choose a capacitor considering the allowable ripple current, temperature, and frequency corrections!
We would like to introduce a case where an aluminum electrolytic capacitor used in the DC link of an inverter circuit overheated, causing the pressure relief valve to activate and the electrolyte to spray out from the capacitor. The cause was that a ripple current exceeding the allowable value flowed into the capacitor, causing it to overheat beyond its design specifications. Due to the overheating, the insulation deteriorated, leading to a short circuit, and the gas generated from the electrolyte increased the pressure inside the capacitor. The pressure relief valve activated, resulting in the electrolyte spraying out in aerosol form. **Countermeasures** - Confirm that the magnitude and waveform of the expected ripple current during the design phase match the specifications. - Select capacitors considering the allowable ripple current, temperature, and frequency corrections. *For more details, please refer to the PDF document or feel free to contact us.*
basic information
Please be aware of the following: ■ The allowable ripple current is determined by the ambient temperature, the equivalent series resistance at the frequency of the AC signal, the thermal resistance mainly determined by the surface area of the capacitor (heat dissipation area), and the cooling applied. ■ The temperature rise due to ripple current significantly affects the failure of the capacitor. *For more details, please refer to the PDF document or feel free to contact us.*
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A Must-Read Guide for Circuit Designers: 15 Examples of Causes and Countermeasures for Capacitor Failures
Applications/Examples of results
If you see the following symptoms in a capacitor, it is faulty: ■ The case is swollen (bulging) ■ There are cracks in the case ■ There is a gap between the case and the sealing part ■ The pressure valve has activated (the pressure valve has opened) ■ The case has burst ■ It is hot or generating heat ■ Smoke is coming out ■ There is liquid leakage ■ There are unusual sounds ■ There is an unusual smell *For more details, please refer to the PDF document or feel free to contact us.
