| 摘要 |
PURPOSE:To attain the duty control of a power by a relay by switching on/off of a relay contact around zero voltage of an AC power supply to improve the life of the contact. CONSTITUTION:In case of closing the relay contact 4, when the trailing of a power supply synchronizing signal is inputted, the measurement of time tO is started and a relay driving signal is outputted in a phase coincident with a time ton stored in a memory. In case of opening the relay contact 4, when the leading of the power supply synchronizing signal is inputted, the measurement of time tO is started and the output of the relay driving signal is stopped at a phase coincident with a time toff stored in the memory. Arc discharge is suppressed and the life of contact is improved by deciding the relay driving phase (time ton, toff) that on/off of the relay contact is switched around the zero voltage of the AC power supply. |
