| 摘要 |
PURPOSE:To allow an induction motor surely to switch full voltage starting over to an inverter always in a short time by providing a means to apply the voltage from a commercial power source for the reexciting in residual voltage extinction of a motor when the drive is shifted from full voltage starting to the inverter. CONSTITUTION:A control means is provided to connect an induction motor 3 to a commercial power source 1 only for a specified time from a power supply interruption point in driving the motor in a constant frequency by full voltage starting after the elapse of a specified time. In compliance with the power connection by this control means the operation of an inverter 2 in a specified frequency is started by the residual voltage generated from an induction motor 3 and the operation is to be shifted to the variable frequency drive by the inverter 2. The switching of full voltage starting over to the inverter 2 can thereby be performed within a pretty short time regardless of the rotation inertia quantity of a motor load, making the most of the merit to reduced the inverter capacity by switching the full voltage starting over to the output of the inverter 2. |
