OnLine Power Battery Backup System - Manual (Page 43)

OLP
Three Phase UPS Systems
4.0 OPERATION
4-4
(c) Open the rectifier breaker – Opening the rectifier breaker will take the
power source away from the DC bus, causing the DC bus to drop
slowly. After 5 min., the DC bus will drop to a safe level
(<20VDC).
(d) Close the bypass breaker – The reserve breaker and reserve static switch
are still conducting. Therefore, when the maintenance bypass
breaker is closed, power will flow through the bypass loop instead
of the reserve loop.
(e) Open the reserve breaker – You can now open the reserve breaker to free
the UPS from any power supply.
4.4. From Maintenance Bypass to Inverter Procedure
If the UPS is in maintenance bypass mode, and you want to turn the UPS to
normal mode without interrupting the output AC, please follow the steps below.
(a) Close the reserve breaker – The reserve and output LED on the mimic will
light, indicating the reserve static switch loop is energized, and
the output has power. The power supply in the UPS is also
established, and the fans will operate.
(b) Open the bypass breaker – The inverter cannot be switched on while the
maintenance bypass breaker is closed (because the CPU will
sense the breaker and prevent the inverter from connecting
directly to AC source). Since the reserve breaker is already closed,
power goes through the reserve loop if the bypass breaker is open.
Thus, AC at the output will not be interrupted.
(c) Close the rectifier breaker - The rectifier will be automatically started if the
power source connected is correct. Wait 30 sec for DC bus
voltage to rise until the warning LEDs of “BAT LOW” and “BAT
LOW STOP” go off (on the front panel). Now, the DC is already
ready for the inverter.