Figure 5-2 Path Of Current Through The Ups In Standard Normal Mode - Eaton 9EHD-33-40/20 User's Installation And Operation Manual

If the UPS becomes overloaded or unavailable, the UPS switches to Bypass mode. The UPS automatically
returns to Normal mode when the overload condition is cleared and system operation is restored within
specified limits.
If the UPS suffers an internal failure, it switches automatically to Bypass mode and remains in that mode until
the failure is corrected and the UPS is back in service.
44 Eaton 9EHD UPS (20-40 kVA, 380/400/415V) Installation and Operation Manual
(Optional)
Bypass Breaker
Bypass Input
Rectifer
Input
Input Breaker
Input
Contactor
Breaker Contactor

figure 5-2 Path of Current Through the uPS in standard normal mode

Static
Switch
Rectifer
Battery
Converter
Closed
Open
Battery
Inverter
Battery
Contactor
Output
Output
Contactor
Main Power Flow
Trickle Current
Energised
De-Energised