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Chapter 8 Parallel System
93
8.3 External Power Distribution
Parameters such as maximum permissible input current (In is the rated input
current) of each UPS, capacity of input circuit breaker(suitable for rectifier input and
bypass input) are given in Table 3-5. It is recommended that the input power source
of each UPS unit should be input to its own circuit breaker in the switchgear. The
battery group shouldn’t be shared among the UPS units. Each UPS unit should be
equipped with an output circuit breaker for the convenience of switching off the
UPS during maintenance. The capacity of the output switch of the power cabinet
should be selected according to the maximum capacity of the parallel operation
system considering the redundancy. The specifications of the switch are given in
Table 8-2.
Table 8-2 Output Power distribution parameters
UPS capacity Capacity of output circuit breaker
20kVA 30kVA 40kVA 60kVA
Single module UPS system 63A 63A 100A 100A
1+1 63A 63A 100A 100A
2+1 125A 125A 200A 200A
3+1 200A 200A 300A 300A
4+1 250A 250A 400A 400A
5+1 300A 300A 500A 500A
6+1 400A 400A 600A 600A
7+1 450A 450A 700A 700A
Parallel
operation
modes
8 UPS units 500A 500A 800A 800A
8.4 Start up of Parallel Operation System
Check the input and output wiring of each UPS unit. Ensure that the phase rotation
of the rectifier, bypass and output of each UPS unit is same. Ensure the parallel
connection cables are connected firmly.
1. Switch on the UPS units one by one and check their operation states:
(1)Commission each UPS unit referring to Chapter 4 for the methods.
(2)Set the parameters of each UPS unit through background host and adjust the
parameters of parallel operation system.
Configuration setup: Each UPS unit should be set as “parallel” mode. The UPS unit
that is connected to the background host should be set as “connect to background
host”;