Windows
Click Printer and Option Information on the printer driver's Maintenance tab.
Disable the Power Off If Inactive and Power Off If Disconnected settings.
Disable the Power Off Timer setting.
Mac OS
Select System Preferences from the menu > Printers & Scanners (or Print & Scan, Print & Fax), and then select the printer. Click Options & Supplies > Utility > Open Printer Utility, and then click Printer Settings.
Disable the Power Off If Inactive and Power Off If Disconnected settings.
Disable the Power Off Timer setting.
Your product may have the Power Off Timer feature or Power Off If Inactive and Power Off If Disconnected features depending on the location of purchase.