Patent ID: 8347134

Claim:
A power control system for a network system in which a plurality of devices are connected over a network, each of the plurality of devices including: a mode changeover unit that operates a local device in one of a plurality of modes specified by a mode changeover instruction, the plurality of modes including a low-power mode, a normal mode having a maximum consumed power value greater than a maximum consumed power value in the low-power mode, and a high-power mode having a maximum consumed power value greater than the maximum consumed power value in the normal mode; and a mode controller that sends a first power accommodation request to other devices in case of determining that power becomes insufficient when the local device is operating in the normal mode, outputs a mode changeover instruction instructing an operation in the high-power mode to the mode changeover unit in case of determining that a total of accommodatable power values sent from the other devices in response to the power accommodation request is equal to or greater than a needed power value needed for transition to the high-power mode, and sends a difference between the maximum consumed power value in the normal mode and the maximum consumed power value in the low-power mode as an accommodatable power value to a sender device which has sent a second power accommodation request in case of receiving the second power accommodation request when the local device is operating in the low-power mode, wherein a total of the maximum consumed power values of the individual devices in the normal mode matches with a maximum suppliable power value suppliable to the network system.