| 摘要 |
PURPOSE:To prevent a damage caused by the deterioration in the insulation of a brush due to the accumulation of worn powder of the brush by providing a normally measuring and monitoring circuit for the insulating resistance of a motor. CONSTITUTION:An insulating resistance measuring circuit 20 has an insulating resistance measuring instrument 22 for measuring leakage current, a comparator 23 for producing an air blow alarm signal, and a comparator 24 for producing an armature current zero signal, thereby always measuring the resistance between the armature and the ground (the case of a DC motor) of a DC motor 17. When the resistance value becomes lower than the predetermined value, an armature current zero command is outputted, thereby stopping the motor 17. |
