Instructions
Turn on your PlayStation 3.
Select "Settings" from the main menu.
Chose "Power Save Settings."
Select "System Auto Off" to view the settings related to your PlayStation 3's automatic power shut off feature.
Select your desired option from the list on screen. You can choose to have your PlayStation 3 automatically power off after one hour, two hours, three hours or five hours. Conversely, you can select "Off" to disable this feature altogether. Making the selection will change your console's settings.