| 摘要 |
PROBLEM TO BE SOLVED: To prevent erroneous decision when insulation test is performed and at the same time to detect the welding of a contact to cut off the supply of electric power by supplying electric power to the open and close detection circuit of the temperature switch of a compressor from the compressor side of the electric power opening and closing contact of the compressor. SOLUTION: Electric power is supplied to a compressor 3 by turning on a power relay 2 having a normally open contact through a coil 2a by an auxiliary relay 4. The generation of abnormally high temperature in operation of the compressor 3 is detected by a temperature switch 5 having a normally close contact to open the auxiliary relay 4 through a coil 4a by the microcomputer 7 of a temperature switch detection circuit 8 and to close the power relay 2, thereby stopping the operation of the compressor 3. In the control device of the above-mentioned compressor, electric power is supplied to the open and close detection circuit 8 from the compressor side of the secondary side of the power relay 2. Therefore, the capacitance 6 between the temperature switch 5 and the ground is separated by the power relay 2 in an insulation test, and a leakage current due to the capacitance 6 is eliminated. Also, the welding of a contact can be detected by determining the state of the contact of the power relay 2. |
