UPS471-02-00 PW9000DPA User Manual UK Dated 06/08/14
7
2: General Description
If the mains supply fails, the LINE 1 led will extinguish and the rectifier will shut down. The battery now provides an
alternative DC power source for the inverter via the charger/booster and the BATTERY led will flash green to indicate that
it is on load.
Larger installations often include a standby generator which is designed to start-up and connect to the UPS automatically
within a short period of time following a mains failure. Once the UPS input power is restored from the standby source the
rectifier and charger will resume normal operation, which results in very short battery discharge periods.
In the case of a dual feed input
– if the bypass supply remains live, the
LINE 2
led will stay illuminated and the inverter
frequency will remain synchronised to the bypass provided it stays within its preset limits.
In the case of a single feed input
– the bypass supply will fail at the same time as the mains supply and the
LINE 2
led will
extinguish along with the
LINE 1
led. Under these circumstances inverter frequency will revert to a free-running oscillator
that will produce a constant 50/60Hz UPS output.
Battery discharge operation
Various alarms are generated at preset levels as the battery discharges. This allows the operator observe the remaining
autonomy and, if required, shut-down the load in an orderly manner (e.g. to save data) before the battery reaches its final
end-of-discharge voltage. Various options are available to automate the load shut-down process, as described in Chapter
8 of this manual (Options).
When the battery is initially put on load the
BATTERY
led will flash green, as shown in Figure 2.5. This will continue until
the remaining autonomy time falls to 3 minutes whereupon the led will begin flashing red and if a data protection
application, such as WAVEMON, is installed it will begin its automatic PC shutdown routine at this point.
When the battery reaches its fully discharged voltage the
BATTERY
led will change to solid red and the UPS will attempt to
transfer the load to the bypass supply if it is present.
Load on Bypass
Figure 2.6 Load on bypass
In the ‘load on bypass’ mode the load supply is connected to the unprocessed static bypass line via the static switch.
Depending on the reason for switching to bypass operation (i.e. manually transferred or transferred due to a fault), when
operating in this mode the rectifier/charger section can be turned off entirely or remain running, and continue to provide
battery charging (as shown above). Similarly, the inverter may have been manually turned
OFF
or shutdown due to a fault,
and the
INVERTER
led may be
OFF
or solid
RED
.
Static switch operation
The static switch is a solid state switch contained in each power module and operated by the module’s microprocessor
control logic which ensures that the static switch of all the power modules connected to the load (through IA2) are always
in the same operational state. It is not permissible for one module to be operating with ‘load on inverter’ while the
remaining modules are in the ‘load on bypass’ mode as such a situation would cause damage to the modules.
During normal operation the load is transferred from the inverter to the static bypass line in the event of an overload or loss
of system redundancy due to a failed power module. Load transfer can also be initiated manually via the UPS operator
control panel located on the front cabinet door
(see paragraph 2.3.3)
.
MAINTENANCE
BYPASS
LINE
BATTERY
Bypass
Supply
Mains
Supply
Load
Supply
IA1
IA2
STATIC
SWITCH
PW9000
DPA
Cabinet
STATIC
BYPASS
LINE
Charger
INVERTER
RECTIFIER
LINE 1
LINE 2
BY PASS
INVERTER
BATTERY
LOAD