ETL EDP70 - Manual (Page 13)

MI00/10056 rev. 8 — 05/2006-- page 13
Figure 5 – Re-establishing the Utility Supply
When the utility supply returns within acceptable limits, the UPS returns automatically to normal operation mode as
previously described. The rectifier now starts to recharge the battery. However, until recharge has been completed, any
further mains failure will result in reduced standby times.
Figure 6 – Transferring the Load onto the Reserve Supply
Transfer onto the reserve line is caused by two conditions:
a) inverter stop
b) overload
In both instances the load is transferred onto the reserve without interruption. If the overload is temporary, the system will
re-transfer from reserve to inverter as soon as the it ceases. This allows for the initial start-up of loads with high or
excessive switch-on currents.
S1
AC Supply
Reserve Supply S2
S3
Battery
Contactor
AC Supply
Reserve Supply
S1
S2
S3
Battery
Contactor
Maintenance By-pass
S4
S5
50/80kVA Ratings
208Y/120V
480Y/277V
Maintenance By-pass
S4
24/36kVA Ratings
S1
AC Supply
Reserve Supply S2
S3
Battery
Contactor
AC Supply
Reserve Supply
S1
S2
S3
Battery
Contactor
Maintenance By-pass
50/80kVA Ratings
208Y/120V
480Y/277V
S5
S4
Maintenance By-pass
24/36kVA Ratings
S4