| 摘要 |
PURPOSE:To prevent the burning of a motor or a clutch coil at the time of overload by comparing the speed command value and the speed of a machine shaft, and by disabling the driving mechanism in the case the output of the comparison is larger than the specified value for the specified period. CONSTITUTION:In the case the output of a tacho-generator TG is smaller than a command voltage SV, a clutch coil CL is energized through an operation amplifier OP and a transistor T3. In the case the machine speed in high, a braking coil BR is energized. When the machine is overloaded, a transistor T4 is turned on at the time the voltage of capacitor C1 becomes higher than the voltage of a constant voltage element ZD3, and the clutch coil CL is cut off. A monostable multivibrator MM is operated for a specified period, a transistor T1 is turned off, and a brake coil BR is energized. Therefore, the excitation of the clutch coil does not last long, and the motor and the like can be protected without fail. |
