GE 300, 225 manual Power Wiring of Parallel Units, RPA Parallel System

g

GE

3.9POWER WIRING OF PARALLEL UNITS

To guarantee good Load sharing between the units of a parallel system, we recommend it is recommended that the cable length from the input distribution board (5) to the output distribution board (10) are the same length 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.

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 disconnect or isolation switch be inserted in order to totally isolate a unit if needed

Verify that power wiring and control wiring are run in separate conduits or cable trays. UPS input cables must be run in separate conduits from the output cables.

Fig. 3.9-1 RPA Parallel System

1 = Rectifier

2 = Inverter

3= Electronic Bypass

4= Manual Bypass

5= Input Utility Distribution

6= Unit Output Load

7= External Battery MCB

8= External Battery fuse

9= External Battery

10= Common Busbar and Output Load Distribution

c= Unit Number 1

2	=	Unit Number 2
3	=	Unit Number 3
4	=	Unit Number 4
5	=	Unit Number 5
6	=	Unit Number 6
7	=	Unit Number 7
8	=	Unit Number 8

In a RPA configuration with 3-wire kit, it’s most important to connect the Neutrals of the UPS outputs together (see Fig .3.8.2-2 and 3.8.3-2). Cable section for this connection shall be not less then AWG 1

OPM_SGS_ISG_M22_M30_0US_V011.doc 29/38 Installation Guide SG Series 225 & 300 kVA