| 摘要 |
PURPOSE:To provide an overload stopping circuit for motor in which a motor can be stopped easily at low cost upon elapse of time. CONSTITUTION:The overload stopping circuit 3 for motor detects overload from the current flowing into a motor 1 and can interrupt the current. The circuit 3 comprises a current detecting circuit 31, PTCs 32p, 32m, triacs 34p, 34m, and a resistor 35. The PTCs 32p, 32m are connected in current paths 30p, 30m and exhibit high resistance when a current higher than a predetermined level flows. Series circuit of the triacs 34p, 34m is connected between the current paths 30p, 30m on the motor 1 side of the PTCs 32p, 32m. When the current flowing into the motor 1 exceeds a predetermined reference level continuously for a predetermined time, the current detecting circuit 31 turns the triacs 34p, 34m ON. Consequently, the resistance of the PTC 32p or 32m increases to limit the current flowing into the circuit thus protecting the motor 1. |
