Your question is not entirely clear, as exact information is missing. But my guess is that the hard disk is connected to the computer all the time. Then it normally goes into standby mode after some time without activity and switches off. When the operating system accesses or impulses it, it wakes up again and spins up.
USB power saving settings can be set in the energy saving options of Windows. Simply deactivate the setting selective USB power saving under USB settings. If necessary, also deactivate Shutdown after . . with 0 (minutes).
If the hard drive still switches off, this is probably due to an internal power saving function of the Intenso and does not represent a malfunction.