A "ripple current" is the RMS value of a superimposed AC current of any frequency and any waveform of the current curve for continuous operation at a specified temperature. It arises mainly in power supplies (including switched-mode power supplies) after rectifying an AC voltage and flows as charge and discharge current through the decoupling or smoothing capacitor. The "rated ripple current" shall not exceed a temperature rise of 3, 5 or 10 °C, depending on the capacitor type, at the specified maximum ambient temperature.
Ripple current generates heat within the capacitor body due to the ESR of the capacitor. The ESR, composed out of the dielectric losses caused by the changing field strength in the dielectric and the losses resulting out of the slightly resistive supply lines or the electrolyte depends on frequency and temperature. Higher frequencies heighten the ESR and higher temperatures lower the ESR slightly.
The types of capacitors used for power applications have a specified rated value for maximum ripple current. These are primarily aluminum electrolytic capacitors, and tantalum as well as some film capacitors and Class 2 ceramic capacitors.
Aluminium electrolytic capacitors, the most common type for power supplies, experience shorter life expectancy at higher ripple currents. Exceeding the limit tends to result in explosive failure.
Tantalum electrolytic capacitors with solid manganese dioxide electrolyte are also limited by ripple current. Exceeding their ripple limits tends to shorts and burning components.
For film and ceramic capacitors, normally specified with a loss factor tan δ, the ripple current limit is determined by temperature rise in the body of approximately 10 °C. Exceeding this limit may destroy the internal structure and cause shorts.
Other articles related to "ripple current, current, ripple":
... Ripple current is the AC component of an applied source (often a switched-mode power supply) (whose frequency may be constant or varying) ... Ripple current causes heat to be generated within the capacitor due to the dielectric losses caused by the changing field strength together with the ... well as some film capacitors have a specified rating value for maximum ripple current ...
... While this happens with normal aging, high temperatures and large ripple current exacerbate the problem ... In a circuit with significant ripple current, an increase in ESR will increase heat dissipation, thus accelerating aging ... Therefore polymer capacitors can handle higher ripple current ...
... These chargers can supply either a constant voltage or a constant current to the battery ... Simple AC-powered battery chargers have much higher ripple current and ripple voltage than other kinds of battery supplies ... When the ripple current is within the battery-manufacturer-recommended level, the ripple voltage will also be well within the recommended level ...
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