15
The master controller monitors internal and external battery currents, which enables the microcontroller
to determine: a) that the external batteries or battery breakers, if used, are functioning, and b) proper
charging current is sent to the battery systems. The heat sink, inside ambient and room temperatures
are monitored for the protection of the equipment itself.
Figure 8 System Block Diagram
AC Breaker
Surge
Suppr.
3
Φ
AC
Input
High Speed
SS Switch
Maint.
Bypass
Switch
3
Φ
AC
Output
Main Battery Breaker
Ext. Batt.
Breaker
External Battery
Cabinets
Internal
Battery
Ι
Β
Temp Sense
Master
Control
Voltage
Interface
Input
Output
and
Battery
Voltage
Keypad
& LCD
Remote
Commun
RS232 Port
Status Relay Contacts
Gate
Drives
Ι
DC
Ι
L
3
Φ
Inverter
LC
Filter
3
Φ
Inverter
Transformer
Only systems
w/internal batteries
System Power Wiring Diagrams
– The system power wiring diagrams are found in Figures 9A and
9B. These wiring diagrams are for a size 1, 20 battery UPS. Similar diagrams can be found posted on
the inside of the door of the UPS. Figure 9A shows the wiring associated with the DC voltage circuitry
whose major components consist of the internal batteries, DC breaker(s), DC Power contactor, inverter,
and inverter output filtering. A size 1, 18 battery UPS has identical wiring, except the group of 2
batteries on the right side of the lower shelf does not exist. A size 2, 20 battery UPS also has identical
wiring except the batteries are configured in groups of two because each tray has two 65 amp-hr
batteries instead of three 38 amp-hr batteries. A size 2, 20 battery UPS has 10 trays of batteries, five
trays on each shelf. A size 2, 18 battery UPS has 9 trays of batteries with 5 trays on one shelf and 4
trays on the other shelf. The AC voltage circuitry shown in Figure 9A is identical for all UPS sizes. It
contains AC voltage circuitry whose main components consist of the AC input and output terminal
blocks, AC breaker, transfer switch, input surge suppression, AC IGBT switches for switching on and
off the input AC, and the 3-phase power transformer.
