| 摘要 |
A power supply apparatus includes a power supply unit disposed within a casing. The power supply unit includes power semiconductor devices. A fan is provided in the casing for cooling the power semiconductor devices. The power supply unit is operated in a plurality of contiguous cycles each including a running and pausing modes of operation. Each cycle lasting a relatively short time period. The power supply unit operates in the running mode and the pausing mode, respectively in response to the closing and opening of a start switch. In association with the closing and opening of the start switch, a switch for the cooling fan causes the fan to rotate and stop, respectively, which results in minimizing the difference between the highest and lowest temperatures of the power semiconductor devices so that the lifetime of the power semiconductor devices can be prolonged.
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