Stacking, Parallel stacking, Phase stacking – Outback Power Systems Systems User Manual

Page 13: Outback series/parallel stacking, Classic series stacking, More power for three-phase loads, More power at all output voltages

2005

OutBack Power Systems Inc.

Stacking

At OutBack, we adhere to a philosophy that a power system should be fully customizable to address your speciﬁ c

needs. Th erefore we set out to create the world’s only group of inverter/chargers that use a truly modular architecture.

Th is modular architecture uses the next generation of a technique referred to as “stacking” to enable you to tailor your

system for higher output power, increased charging capabilities and/or three-phase power conﬁ guration.

Whether stacked in parallel, classic series, series/parallel or three-phase there is always an inverter/charger which

performs the task of Master. Th e Master talks to the other units through the HUB system communications manager

while performing three major roles, keeping all inverter/chargers properly phased, controlling inverter and charger

output levels, as well as putting unused inverters into Power Save mode to improve eﬃ ciency at low AC load levels.

Parallel Stacking

- More power at same output voltage

When the inverter/chargers are stacked in parallel all inverter and charger outputs are combined. Th is means that each inverters AC output

is added up to equal your total system AC output, up to 36,000 watts, in phase at the same 120 VAC/60 Hz or 230 VAC/50 Hz output voltage.

Charging output amperage is also combined in this same manner.

3 kW

120 VAC

3 kW

120 VAC

3 kW

120 VAC

9 kW

120 VAC

Leg 1

9 kW

120 VAC

Leg 2

3 kW

120 VAC

Leg 1

3 kW

120 VAC

Leg 2

9 kW

120 VAC

12 kW

240 VAC

Leg 1

and

Leg 2

6 kW

240 VAC

Leg 1

and

Leg 2

9 kW

208 VAC

3-Phase

Load

3-Phase Stacking

- More power for three-phase loads

Th ree inverter/chargers can be conﬁ gured to provide 120/208 VAC or 230/400VAC four wire “Wye/Star” three-phase AC Power. An inverter/

charger is used to power each of the three legs for 3-phase AC power. Th e loads on each of the inverters does not need to be kept balanced,

each phase is independently voltage regulated.

OutBack Series/Parallel Stacking

- More power at all output voltages

Series/Parallel stacking or OutBack (OB) stacking is unique to OutBack inverter/chargers. Never before has it been possible to have inverter/char-

gers balancing loads intelligently between two legs of AC power while seamlessly changing between series and parallel. OB Stacking uses the X-240

auto transformer to balance the loads between the two separate series legs of a system. Th e X-240 allows AC loads on leg 1 and leg 2 to be powered

by any combination of inverter/chargers within your system. Even if there are only two inverter/chargers, connected in series, they can also func-

tion as if connected in parallel. Th is allows larger AC loads to be operated by a system without risking overloading one of the 120 VAC outputs.

Classic Series Stacking

- More power at higher output voltage

Stacking inverter/chargers in classic series provides a system with split phase 120/240VAC. Th is method does not allow balancing between

separate legs on a system and is can only be used in dual inverter/charger systems without the X-240 Auto Transformer.

3 kW 120 VAC

X-240