Rpa Parallel System Connection; Power Wiring Of Parallel Units - ABB MegaFlex 1000 UL S1 Installation Manual

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4.10 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).
Use Class 2 method for RPA cables.

4.10.1 Power wiring of Parallel Units

To guarantee good Load sharing between the units of a 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: +/-20%.
The AC input power of the Bypass must be the same for all units of the Parallel System - no phase shift allowed
between units.
Note!
It is strongly recommended that no Transformers, Automatic Circuit Breakers 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. 4.10.1-1 Power wiring of RPA Parallel System
MegaFlex 1000 to 1600 UPS Installation Guide / REV-A
1 = Rectifier
2 = Inverter
3 = Automatic Bypass
4 = Input Utility Distribution
5 = Unit Output Load
6 = Battery Circuit Breaker
7 = External Battery
Common bus bar and
8 =
Output Load Distribution

= UPS number 1
k
= UPS number 2
l
= UPS number 3
m
= UPS number 4
n
= UPS number 5
o
= UPS number 6