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An electrolytic capacitor, used as a smoothing filter, is more sensitive to variations in the ambient temperature because of the
chemical reactions which occur within it.
Typically, the service life of electrolytic capacitors halves for every ambient temperature increase of 10ºC. This characteristic
determines the service life of most DC-DC converters.
Fig. 21 shows the relationship between the service life of the DC-DC converter and ambient temperature. If the DC-DC
converter is used at high temperatures, the electrolytic capacitor may enter the fatigue failure period while the other parts are
still in the random failure period. To increase the service life of the DC-DC converter, it may be necessary to replace some
electrolytic capacitors.
Fig. 21
6.3 OVERHAUL
As technology improves, the number of continuous operating systems increases. And though the service life of DC-DC
converters is also increasing, they cannot be relied upon forever.
Therefore, periodic overhauls are required to ensure the reliability of any equipment. How often an overhaul needs to be
performed on a unit depends on the operating conditions and temperature. Service life is most seriously affected when a unit is
operated continuously. In this case, the frequency of overhauls to the DC-DC converter should be as follows:
Ta is between 40ºC and 45ºC - once every three years
Ta is between 35ºC and 40ºC - once every four years
Ta is between 30ºC and 35ºC - once every five years
Where: Ta indicates the ambient temperature of the DC-DC converter.
The above temperature values may differ depending on the type of DC-DC converter used. For more details on overhauls and
service life, contact the manufacturer.
6.4 LOAD CAPACITY AND AMBIENT TEMPERATURE
A DC-DC converter's operating temperature depends on input voltage, output load, ambient temperature, and cooling. The most
ideal way to increase the service life of a converter is to NOT continuously operate it at full capacity. This becomes even more
critical in warmer climates or conditions.
Example: Two identical DC-DC converters (subjected to the same environmental conditions) were operated using different
loads. One had a 40% load condition and the other had an 80% load condition. The test showed that the unit with the 40% load
lasted four times longer that the unit with the 80% load condition.
Every new model of the Mean Well DC-DC converter range is subjected to an environmental test during the prototype phase.
Fig. 22 on the next page shows how temperature probes are connected to the unit. Figures 23 and 24 show the typical rise in
temperature for each of the temperature probes with increasing load for two different models.
