| 摘要 |
PURPOSE:To prevent a regenerative resistor from flowing a current at defective mode time and from burning by inserting a temperature fuse mechanism into a series circuit of the resistor and a regenerative transistor. CONSTITUTION:A 3-phase AC is converted into a DC by a rectifier of diodes D1-D6, and a 3-phase induction motor M is driven through an inverter of a capacitor C1 and transistors Tr1-Tr6. A regenerative device 1 is connected in parallel with the capacitor C1. The device 1 connects a capacitor C3 in paral lel with a protecting unit 2 and connects a series unit of a regenerative resistor R1 and a regenerative transistor Tr7 with the connecting point. This protecting device 2 is composed of a heater resistor R3 and a temperature fuse mechanism of a contact SW1 (normal-closed contact). Thus, when a transistor Tr7 is dam aged, an excess current is flowed to the device 2, the resistor R3 is heated to high temperature to open the contact SW1. The contact SW1 is not automati cally reset even if the temperature falls. |
