This input is used to activate the load reserve set #3 instead of the set #1,
which is active by default. The set #3 is adjusted by setpoints:
#LoadResStrt 3 and #LoadResStop 3 if the power management is
switched to absolute (kW-based) mode
#%LdResStrt 3 and #%LdResStop 3 if the power management is
switched to relative (%Pnom-based) mode.
CAUTION!
All controllers cooperating together in Power management must have the
same load reserve set selected.