2: General Description
4
TS_616_08 PW8000DPA ST (S2) User Manual 21/4/22
The PowerWAVE 8000DPA ST (S2) is a truly flexible, modular UPS system designed around 10 kW or 20 kW UPS power
modules. Up to ten UPS modules can be installed in a range of purpose-designed, free-standing cabinets, as shown in
Figure 2.1. The UPS cabinet is rated according to the maximum number of 20kW modules that it can house – i.e. 40 kW,
60 kW, 80 kW, 120 kW and 200 kW. The 40 kW and 60 kW cabinets contain the UPS batteries but the 80kW, 120 kW and
200 kW models require external batteries which are usually contained in a purpose-designed battery cabinet that is
installed as close as possible to the UPS cabinet. A range of matching battery cabinets is available.
2.2.2 Advanced design features
Decentralized Parallel Architecture (DPA)
The PowerWAVE 8000DPA ST (S2) system features Decentralized Parallel Architecture (DPA) paralleling technology that
provides N+x redundancy without introducing a single-point-of-failure. Each power module is a fully functional, self-
contained UPS that includes an individual battery charger, power inverter, bypass, CPU, control panel and separate
battery configuration; making it a completely autonomous operating unit.
The outputs from all the modules fitted in a UPS cabinet are connected in parallel at the cabinet’s output terminals, and the
electronics built into each module’s control system ensures that:
• The UPS modules equally share the load current.
• The inverter/bypass load transfer operation is synchronised such that, for example, if the operator selects ‘bypass’
mode the static switch in ALL the modules change over in unison.
• The UPS modules are always frequency-synchronised to each other – and to the bypass supply (when present).
Note: The parallel control mechanism is applied on a ‘master’/ ‘slave’ basis in which one module (usually
module 1) is set as the ‘master’ module and the remaining modules as ‘slaves.’ If the ‘master’ module shuts
down, the next module in the chain will take over the ‘master’ role automatically.
Hot swappable modules
Although the illustrations in Figure 2.1 show fully populated UPS cabinets, thanks to the UPS module’s advanced
Distributed Parallel Architecture (DPA) design it is possible to operate the PW8000DPA ST system with just a single
module fitted – additional module(s) can then be installed to expand the system capacity as needed, without needing to
shut down the system or transfer the load to the bypass supply.
This ‘hot-swappable’ design similarly allows a UPS module to be exchanged during UPS operation without disrupting the
load supply – but of course this depends on the system redundancy and the load demand at the time the exchange takes
place.
Input booster technology
The PowerWAVE 8000DPA ST (S2) UPS module’s advanced booster technology results in an input power factor of 0.99
with a harmonic content of <4.5% THD (10KW module) and <3% THD (20KW module). This enhances the system
reliability and minimises the winding losses of any generator or transformer connected to the UPS input, which in turn
reduces the generator/transformer costs. It also overcomes the need for an input harmonic filter, resulting in further
savings.
Cabling and fusing costs are also reduced as a result of the high input power factor due to the low reactive power
consumption.
In summary, the benefits of the UPS module’s high input power factor are:
Key Point:
All the modules fitted within a UPS cabinet must be of the same rating.
• reduced cable losses
• reduced heating of transformers and generators
• no over-sizing of generators required
• no false circuit breaker tripping and malfunction
• no erratic operation of sensitive connected loads
• no resonance with power factor correction capacitors
• low input harmonic currents