| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for protecting contacts of an earth leakage detection relay by satisfactorily removing oxide films on the contacts of the earth leakage detection relay. <P>SOLUTION: In an electric water heater, earth leakage detection relays (7, 8) to be opened at the occurrence of earth leakage are connected to an energizing circuit (9). When current flows through the energizing circuit (9) after the lapse of a fixed time, control for opening the earth leakage detection relays (7, 8) is performed by control of an electric water heater control microcomputer (12). When the earth leakage detection relays (7, 8) are opened, an arc is generated between contacts of the relays (7, 8), thereby removing oxide films on the contacts of the relays (7, 8). <P>COPYRIGHT: (C)2013,JPO&INPIT |
