12
10. If your unit has an SNMP or relay contact card fitted or you plan to use the RS232 port or other
standard signals, see Appendix 1 Signals options on page 24.
Wiring units in parallel
You can operate 2, 3 or 4 units in parallel. Each unit must be ordered with a factory fitted parallel board
option.
Caution:
If you are using units with external batteries, each unit requires its own battery bank.
You cannot use a common battery bank for more than one unit working in parallel mode.
When operating units in parallel you must not use the built-in bypass as it is rated for one unit
only. If you need a bypass for the parallel system it must be wired as an external item.
WARNING!
BEFORE ATTEMPTING TO WIRE THE UNITS, ENSURE ALL BREAKERS ARE IN THE OFF
POSITION.
To connect two or more units in parallel:
1. Wire the power cables and optional signals as described above.
2. If a system bypass is required, wire in a separate MCB capable of carrying the total system load
current as shown below. This is not required if you have only two units working in N+1 mode where
the load never exceed the rating of a single unit.
3. On the parallel board of each UPS, connect the CAN bus labelled
Parallel 1
and
Parallel 2
, in a ring
arrangement using the supplied RS232 cables as shown below. Make sure you wire all CAN bus
connectors and secure them in place using their captive screw locks.
VFI-KT Series User Manual
