| 摘要 |
PURPOSE:To distinguish a high load time from a lock time to protect a motor at the high load time of motor and lock time of compressor by increasing the output frequency of inverter at a time until the difference appears in the input currents of inverter. CONSTITUTION:The output frequency of inverter 6 is controlled at a controller 20 outside a room according to air conditioning load obtained by a controller 10 inside the room and a motor 7 is operated to drive a compressor. The control ler 20 inputs voltages of both ends of shunt resistor 5 and detects that the input voltage of inverter 6 is excessive. The controller 10 drives a power relay 3 to nonexcitation conditions at a circuit 11 to open a contact 3a. In this case, an operation frequency changing means 22 is added to the part 20. Until the difference in input currents of inverter 6 appears at high load time of motor 7 and lock time of compressor, the output frequency of inverter 6 is raised at a time. |
