| 摘要 |
An external power-management device controls the supply of electric power from a wall outlet to a refrigerated vending machine. The system includes a switch that couples power in an ON condition and decouples in an OFF condition. The switch is controlled by a controller based on data received from a current sensor, an occupancy sensor, a temperature sensor, and a time-of-year circuit. Upon startup, the current is monitored to determine maxima and minima for the vending machine. The system supplies power to the appliance during business hours as indicated by the time-of-year circuit and while the vicinity is occupied as determined by the occupancy sensor irrespective of the values for current and temperature. Absent the current sensor, the power would be decoupled after a predetermined duration of non-occupancy during nonbusiness hours. However, if the current sensor indicates a high (relative to the previously determined minima and maxima) current at the proposed shutdown time, shutdown is aborted to avoid interruption of a compression (cooling) cycle initiated by the vending machine. The temperature is used in determining when, after shutdown, power is resumed to permit vending machine contents to be cooled.
|
