Microsoft Excel includes a powerful feature of saving your document
automatically after some specified time
intervals.
By default, Excel automatically saves your current document after every
ten minutes
intervals
but
you can change this time. This Auto save feature save the data in the
same file. However, AutoSave protects your data in the event that Excel
unexpectedly quits. It is also good idea to create a backup of
your files using any removable devices, because in this global network
a computer can crash, a virus create problem, or a hard drive failure
can wipe out everything
Follow the given steps to change default save
time and enable auto backup feature:
A small dialog box will open, here select the Save tab in the
dialog box.

Now click the "Save AutoRecover info every" check box and enter the
time in minutes under "Settings" area.

Here you have choice to modify the location of saving your document
automatically under "AutoRecover save location" option.
Click the Ok button of dialog box to finish the process.