OnLine Power Battery Backup System - Manual (Page 6)

OLP
Three Phase UPS Systems
1. SYSTEM OVERVIEW
1-2
Another important issue is reliability. The prime aim of a UPS is to protect the load.
Therefore, the UPS should be much more reliable than the AC source. An unreliable
UPS suffers the problem of frequent break downs, even more frequent than AC
failure. The cost of repair becomes more than the cost of the unit itself.
Generally, there are four different modes of operation, the NORMAL OPERATION
MODE, the BACK-UP (BATTERY) MODE, the RESERVE MODE and the
MAINTENANCE BYPASS MODE. These are explained below.
Normal Operation Mode:
The rectifier converts the AC input to DC power to supply the inverter and charge the
batteries at the same time. All the fluctuations, surges and spikes of the AC input are
removed during AC to DC conversion. Therefore, the DC supplied by the inverter is
clean and stable.