3: Installation Planning
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TS_616_08 PW8000DPA ST (S2) User Manual 21/4/22
3.3.2 Cable and fuse sizing
Input/bypass mains supply cables
The UPS cabinet can be wired for a ‘single feed’ or
‘dual feed’ (split bypass) mains supply.
In a ‘single feed’ system (standard) the UPS input
mains and bypass mains terminals are linked within
the UPS cabinet, but in a ‘dual feed’ system the
links are removed and the bypass mains terminals
are connected to a dedicated bypass mains supply.
The two configurations are shown in Figure 3.4.
The input supply and bypass supply neutrals are
connected to a common neutral busbar. If the input
mains and bypass mains are obtained from the
same AC power source in a ‘dual feed’ system it is
permissible to connect just one neutral cable.
All input mains and bypass mains cables should be
connected through a LV mains switchboard and
protected by circuit breakers or fuses to provide
overload protection and a means of isolating the
UPS from the mains supply when required.
Note: We recommend that the input cables are
sized for the full cabinet rating even if some UPS
modules are not initially installed. This will allow the
system to be expanded to its full rating without
having to shut it down to up-rate the input cables.
For example: the cables connected to the
PW8000DPA ST-200 cabinet should be rated for
the full 200 kW load even if fewer than ten UPS
modules are fitted.
UPS Output cables
The UPS output cables should be connected to the
load equipment via a suitably fused output
distribution panel.
Note: We recommend that the output cables are
sized for the full cabinet rating even if some UPS
modules are not initially installed. This will allow
the system to be expanded to its full rating without
having to shut it down to up-rate the output cables.
For example: the output cables connected to the
PW8000DPA ST-200 frame should be rated for
the full 200 kW load even if fewer than ten UPS
modules are fitted.
Key Point:
All external fuses, isolators and power cables must be rated and installed in accordance with the
prescribed IEC standards or local regulation – e.g. BS7671.
Figure 3.4 Single and dual feed input configuration
Fuse
C
Cable C
Bypass
Mains
U
V
W
N
Module ‘ ’
n
Fuse A
Cable A
1L3
2L2
2L3
2N
1L1
1L2
2L1
Input
Mains
PE
U
V
W
N
PE
1N
UPS Cabinet
RECTIFIER
STATIC
SWITCH
Module ‘ ’
n
Fuse A
Cable A
Common
Input Links
1L3
2L2
2L3
2N
1L1
1L2
2L1
Input
Mains
PE
U
V
W
N
PE
1N
UPS Cabinet
RECTIFIER
STATIC
SWITCH
Figure 3.5 UPS Output cables
UPS Cabinet
Module ‘ ’
n
Fuse D
Cable D
3L3
3L1
3L2
UPS
Output
PE
U
V
W
N
PE
3N
Module ‘ ’
n
INVERTER
STATIC
SWITCH