User manual

Static Transfer Switch
UNB
User Manual
Page 7 (28)
ELTEK VALERE DEUTSCHLAND ©2009 UM_UNB_E_R04
2.2 Operating modes
The static transfer switch UNB is designed for the operating modes “inverter priority” and “mains priority” alterna-
tively.
Source 1 is defined as priority source, source 2 is defined as substitute source. Source 1 feeds the load as long as
source 1 works faultlessly.
2.2.1 "Inverter priority" (default setting)
REMARK: The unit's default setting is "Inverter priority". In this case the inverters are source 1, mains is source 2.
The UNB switches to source 2 if source 1 fails or is overloaded (i.e. distortions by short circuit behaviour or over-
load).
REMARK: The priority source is programmable using service menu 2.
2.2.2 "Mains priority"
At operating mode “mains priority” AC mains works as source 1 and the inverter(s) as source 2.