GE Industrial Solutions SG Series 50 & 80 kVA Installation Guide - Manual (Page 29)

3.9 RPA PARALLEL SYSTEM CONNECTION
WARNING !
This operation must be performed by trained personnel before the initial start-up.
ENSURE THAT THE UPS INSTALLATION IS COMPLETELY POWERED DOWN.
3.9.1 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 (10) 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 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.
Fig. 3.9.1-1 RPA Parallel System
1 = Rectifier c = UPS Number 1
2 = Inverter 2 = UPS Number 2
3 = Electronic Bypass 3 = UPS Number 3
4 = Manual Bypass 4 = UPS Number 4
5 = Input Utility Distribution 5 = UPS Number 5
6 = Unit Output Load 6 = UPS Number 6
7 = External Battery MCB 7 = UPS Number 7
8 = External Battery fuse 8 = UPS Number 8
9 = External Battery
10 = Common Busbar and Output Load Distribution
Modifications reserved Page 29/38
OPM_SGS_ISG_50K_80K_0US_V040.doc Installation Guide SG Series 50 & 80 kVA