| 摘要 |
PURPOSE: To facilitate maintenance by indicating the service life of a filter capacitor. CONSTITUTION: Ambient temperature T of a filter capacitor 5 is measured by means of a temperature sensor 6, and a ripple current I flowing through the filter capacitor is detected by means of a ripple current detector 7 and delivered to an actual service life determining section 8. At the actual service life determining section 8, service life of the filter capacitor is estimated from the ambient temperature T of a filter capacitor and the ripple current with reference to a characteristic data, stored at an actual service life data storing section, for determining the service life of the filter capacitor from the relationship between the ambient temperature and the ripple of the filter capacitor. The service life thus estimated is delivered to a remaining service life operating section 12. At the remaining service life operating section 12, a used time of filter capacitor measured at a clock section is subtracted from the service life thereof determined at the actual service life determining section 8 to determine the remaining service life of the filter capacitor which is presented at a display section 13. |
