Image Number 7 for United States Patent #7355826.
A current detection unit starts sampling of a motor current at the timing when the motor current has exceeded a threshold value, and holds a maximum motor current value for each prescribed operation cycle. An abnormality determination unit determines whether the maximum motor current value is greater than the threshold value, and counts the number of times that the maximum motor current value continuously exceeds the threshold value. When the count value has reached at least 3, the abnormality determination unit generates and outputs a detection signal indicating abnormality in the motor current to a relay drive unit and a notification unit. The relay drive unit in receipt of the detection signal generates a signal to turn off the system relays. The notification unit generates and outputs a signal AL to display means outside the power supply apparatus.