| 摘要 |
PURPOSE: To extend the service life of a cooling fan installed to a frequency conversion circuit device. CONSTITUTION: A cooling fan 9 is connected to a circuit which leads to a frequency conversion circuit device 5 from a power source in such a fashion that it may be installed in parallel to the frequency conversion circuit device 5 while a relay 10, which is excited accompanied by an ON operation of a raising pushbutton switch PBU or a lowering pushbutton switch PBD of a switching device 2 and excited and released by an OFF operation of the pushbutton switches, is connected to a switching drive control circuit 6. A switching contact 10a, which follows the excitation of a relay 10 and switched ON and switched OFF after a specified lapse of time by excitation release, is installed to a circuit of a cooling fan 9. |
