DC Suitability of AC Appliances

DC appliances are increasingly becoming common-place with the advances in switch-mode power supplies and renewable energy systems. Current devices are designed to operate on 230 VAC. However, many of them include an AC/DC stage that incurs unnecessary losses. This paper investigates the power supply stages of several household appliances to determine their suitability to be supplied directly from a DC source. Three categories of home appliances were analysed: Switch Mode Power Supplies (SMPS), resistive heaters, and lighting equipment. Devices containing SMPS can operate on 325 VDC without any modification as most of their components are already rated for DC. Resistive heaters could work on 230 VDC with minor modifications as their contact switches are not rated for breaking DC currents. Appliances such as phase control circuits, direct-on-line induction machines and step-up/down transformers would need significant modification to operate on DC as these appliances rely on an AC supply to operate.