| 摘要 |
PURPOSE:To make the switching operation unnecessary for the fault of a CPU to control the temperature surely, by switching automatically the system from the schedule operation to the thermostat operation when the CPU becomes faulty. CONSTITUTION:When a CPU (central processing device) 1 is normal, a relay XB is excited by the output of a fault detecting circuit 4, and a contact XB-1a is turned on, and relays X-Xn are turned on and off in accordance with the duty cycle operation signal from the CPU1, and relays XL-XLn are turned on and off also to drive motor compressors CM-CMn intermittently. When the CPU1 becomes faulty, the output of the fault detecting circuit 4 is extinguished, and the magnetism of the relay XB is degaussed, and consequently, the magnetism of relays XL-XLn is degaussed, and power is fed to motor compressors CM- CMn through a series circuit of contacts XL1b-XLnb and temperature regulating thermostats 8-1-8-n to hold the temperature in a set value. |
