Life of Capacitors

Life of Capacitors Life of a capacitor is one of the parameters that developers of electronics consider when selecting the right capacitor. As a rule. European manufacturers state the Useful life parameter in technical specifications of their capacitors. The term is defined by the European standard IEC 60384. This standard specifies that the criterion for the end of the capacitor operation is its overrun of the following parameters: capacity is decreased by more than 30%; the loss tangent is increased more than thrice; the leakage current exceeds the limit stated by the manufacturer. The Useful life is normally indicated for several temperatures. Capacitors are tested for the Useful life value under the following conditions: the capacitor is operating at the rated voltage, with the rated current and a certain temperature (105, 85 or 40° C). The term Load life is based on the Japan-Asian standards and is used primarily by Asian manufacturers. The term Load life is also calculated similarly for the conditions: rated voltage - current - temperature. But the breakdown criteria are more stringent: the capacity is reduced by no more than 20%, the loss tangent is increased no more than twice, and the leakage current is not more than the limit specified by the manufacturer. In the technical specifications there can be another term that could be mistakenly considered an indicator of the life of the capacitor. This term is Endurance. Conditions for such a test are as follows: the rated voltage is applied at a certain temperature, but without the current flow. The following criteria should be satisfied to pass the test: the capacity is reduced by no more than 10%, the loss tangent increases by no more than 30%, and the leakage current is within specification. Endurance, in spite of the narrow tolerances, is not a difficult to test because there is no current and the capacitor does not actually work on the load. That is why such standards define not the maximum amount of time that the capacitor can withstand in a certain mode, but a sufficient value. For different types of capacitors this time is different. For example, for capacitors for general industrial use it is 2000 hours, for capacitors of LongLife category it is 5000 hours. This criterion does not determine limiting capabilities of a capacitor In fact many types of capacitors can pass this test with a much more continuous testing.

Category:

Science & Technology

Tags:

• capacitor
• reliability

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