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4.9 RPA Parallel System connection
Warning!
This operation must be performed only by an ABB Service Technician before the initial start-up
(ensure that the UPS installation is completely powered down).
4.9.1 Power wiring of Parallel Units
To guarantee good Load sharing between the units of an RPA Parallel System, we recommend that the cable
length from the input distribution board (5) to the output distribution board (9) is equal for each unit (a+b = c+d
= e+f = g+h = i+l = m+n = o+p = q+r).
Tolerance: +/-10%.
The AC input power of the Bypass must be the same for all units of the RPA Parallel System - no phase shift
allowed between units.
Note!
It is strongly recommended that no transformers, automatic circuit breakers or fuses should be
inserted between the unit's output and the Load common bus bars.
However, it is recommended that a disconnection or isolation switch is installed in order to totally
isolate a unit if needed.
Verify that power wiring and control wiring run in separate conduits or cable trays.
The power wiring requires two separate conduits: one for input and one for output cables.
Fig. 4.9.1-1 Power wiring of RPA Parallel System
TLE Series 160 to 500 UL S2B
1
2
3
4
5
6
7
8
UPS Installation Guide / REV-A
= Rectifier
= Inverter
= Automatic Bypass
= Input Utility Distribution
= Unit Output Load
= External Battery Fuse
= External Battery
Common bus bar and
=
Output Load Distribution
= UPS number 1
= UPS number 2
= UPS number 3
= UPS number 4
= UPS number 5
= UPS number 6
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