Power Supply Filter Capacitor Failure

Simple shunt capacitor filter reduces the ripple voltage but increases the current through the diode.

Power supply filter capacitor failure.

The reason for this is that the impedance of a capacitor is a function of frequency as explained in the article about impedance and reactance this means that the effect of a capacitor on a signal is frequency dependent a property that is extensively used in filter design. Capacitors are passive two terminal electrical components used to store electricity in an electric field. The lc filter shown in fig. If the capacitor is used as a power supply filter and the capacitor.

In this case the results are much more spectacular with the tantalum capacitor often literally catching on fire and blowing up. Given a diode bridge rectifier that is connected on one set of terminals to the mains via a filter circuit and on the other side to two electrolytic capacitors connected in series. Why the capacitor in your power supply filter is too big january 21 2016 by david williams the job of the capacitor in the output filter of a dc power supply is to maintain a constant dc value by removing as much power ripple as possible. 3 exposure to excessive voltage beyond the rated voltage of the capacitor.

For example a 10 ripple in a 5 v power supply means that the actual output voltage varies by 0 5 v. Capacitors are reactive elements which make them suitable for use in analog electronic filters. And failure of the capacitor. The filter capacitor must usually be large to provide an acceptable level of filtering.

1 2 4 but for basic power supplies lc designs are less popular than rc as the inductors needed for the filter to work efficiently at 50 to 120hz need to be large and expensive. Because these capacitors have a dc value they are actually storing a lot of energy that never gets used. Inside most capacitors there are two metal plates separated by a non conducting substance dielectric. For a typical 5 v power supply a 2 200 μf electrolytic capacitor will do the job.

Capacitor failure modes experience has shown that capacitor failures are second only to semiconductors and vacuum tubes in components prone to malfunction in electronic equipment. The context is a charger circuit more specifically its power supply unit. The bigger the capacitor the lower the resulting ripple voltage. L c filters power supply filters.

This large current may damage the diode and at the same time it causes greater heating of the power transformer resulting in decreased efficiency. Parallel to each capacitor are two discharge resistors. Other times the power supply will kick on as normal and deliver significant power into the shorted tantalum capacitor. Gideon analytical laboratories received an areovox z26p6045m21 45uf 600v capacitor for failure analysis.

1 2 3 is more efficient and gives better results than the rc filter shown in fig. Capacitors for ac applications range from high voltage oil filled devices such as the one shown in figure 5 5 to low voltage high capacitance devices of the type typically found in power.