| 摘要 |
PURPOSE:To effectively protect induction motors by combining the protection against DC overcurrent due to the detection of a DC link current, the protection against an AC overcurrent due to the detection of a phase current, and the protection for limiting the passing current of a transistor. CONSTITUTION:A current from a current detector 5 is read out in an input port 26, and when it is DC overcurrent, an alarm is generated through an output port 27 and a malfunction signal generator 28. A current detected from a phase current detector 11 is read out from the port 26, and when the current exceeds the abnormal value, an electromagnetic contactor MCC is opened through the port 27 and the generator 28. The passing current of transistors Tr1-Tr6 are read out from the port 26. Then, when the passing current exceeds the abnormal value, the abnormal generation signal is output from the port 27,ad the base currents of the transistors Tr1-Tr6 are reduced by driving a transistor controller 13. |
