| 摘要 |
PURPOSE:To protect a motor from breakdown by providing LC filter circuit in power conduction circuit for fan motor of an air-conditioner to absorb noise of motor thereby enabling detection of overcurrent. CONSTITUTION:When applied in a DC motor 1 for rotating a blower fan 3 arranged in an air-conditioner duct 2, an LC filter circuit 5 and a switch circuit 10 are provided in the power conduction circuit. LC filter circuit 5 is comprised of series coils 6, 7 and parallel capacitors 8, 9 to absorb electrical noise produced in the motor 1. Terminal voltage VS across the coil 7 is applied to a comparator 11 to be compared with the setting voltage V0. If VS>V0, H level signal is provided to a delay circuit 13 and if H level signal continues for more than predetermined time (several seconds), H level signal (stop signal) is provided through a hole circuit 14 to a relay coil 10 to open a switch circuit 10. |
