Always
O
n UPS Systems
M0703_NX_Series_Operators_Manual
V1.25
2012-06-12 36
f.
Now that all power has been cut off within the UPS system. All LED’s, displays and fans
should be off.
CAUTION!
Terminal strip and breakers may still be energized if the main input breaker feeding the
UPS system is not turned off or open.
8.3
From Inverter to Manual Bypass Procedure
The following procedures will allow the service personnel to switch the UPS system to
maintenance bypass mode without interrupting the output power to the loads.
a.
Switch off the inverter
– The inverter can be switched off by simultaneously pressing the
inverter off switch (
O
) and the inverter control switch (
◄►
). The load will be automatically
transferred to reserve (utility) supply without interruption.
b.
Open the battery fuse holder
– This will disconnect the batteries from the DC bus and the
UPS no longer has back up available. This fuse holder can be located within the UPS
system or within the battery cabinets.
c.
Open the rectifier breaker
– Opening the rectifier breaker will take the power source away
from the DC bus, therefore, the DC bus will start to drop slowly. After 5 min., the DC bus will
drop to a safe level (approx. 20VDC).
d.
Close the bypass breaker
– The reserve breaker and reserve static switch are still
conducting. When the maintenance bypass breaker is closed, power will flow through the
bypass loop instead of the reserve loop because the impedance of the bypass loop is
lower.
e.
Open the reserve breaker
– You can now open the reserve breaker to cut off any power
within the UPS electronics.
NOTE
: To place the unit into Maintenance Bypass mode the fuse holders behind the control
module (where all control PCB’s are stored) must be opened.
The system is now in Manual Bypass mode (or Maintenance Bypass mode).
CAUTION!
If fuse holders have not been opened power still present and fans will be turning. If fuse
holders open power is still present at the terminal strip and several terminals on the PCB’s.