Installation Guide Manual

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