| 摘要 |
PROBLEM TO BE SOLVED: To provide a detection circuit with a simple structure, which can detect the rotational direction of an AC motor. SOLUTION: A detection circuit 61 involves a detection part 64 and a toggle switch 65. The detection part 64 involves a pair of coils 11, 12 almost along with the rotational direction of a canned motor. A closed loop is formed by connecting a pair of capacitors C1, C2, in series with respective coils L1, L2 through resistors R1, R2. A capacitor C0 for filter is connected to the connecting parts G, H, between the respective resistors R1, R2 and the respective capacitors C1, C2. The connecting parts E, F between the respective coils L1, L2 and the respective resistors R1, R2 are short-circuitingly connected. A switch 65 short-circuits either of the respective capacitors C1, C2 by switching. When a canned motor is rotated, voltage whose phase is shifted is generated at the respective coil L1, L2. By switching the switch 65, the phase shifts of currents flowing through the respective closed loops, can be changed according to its rotational direction. |
