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Installation Manual
Single or '1+N' UPS System
4.4
Maintenance Bypass cabinet (Option)
Bypass cabinet enables maintenance operations and reparations to be performed in full isolation besides allowing the
disabling of each UPS without affecting the ordinary operation of the system (depending on the redundancy level).
The optional maintenance bypass cabinet must be used in all configurations where the internal bypass is not
sufficient to guarantee the power requested by the load.
This cabinet comprises:
• A cut-off isolator for the direct line, which disconnects the bypass line from the load
• Two isolators (see Note 1) to cut-off single UPS outputs
• A cut-off isolator for the output of the whole UPS system
• A terminal block for the auxiliary connections to the UPS's
Note (1): there are alternative solutions differing from suggested standard for specific installation requirements (i.e.
with several UPS cut-off isolators).
Study the reference drawing provided in Chapter 6.
Carefully follow the operating procedures provided in this manual to completely disable the UPS. It is useful to
remember that all input/output power and battery switches must be open for the UPS to be completely insulated.
The UPS system with external maintenance bypass cabinet offers a standard protection that guarantees the blocking
of the inverter and the switching of the load to the bypass line if the maintenance bypass switch is accidentally
closed.
4.4.1
Auxiliary connections between the maintenance bypass cabinet and two UPS's
The maintenance bypass box connected to the terminal blocks requires specific control cabling, as described here
below.
Maintenance Bypass cabinet
X1-1
X1-2
X1-3
X1-4
X1-5
X1-6
UPS 1
X4-7
X4-8
Note: All auxiliary cables of terminal block X1 must be double insulated.
The cross-sectional area of the auxiliary cables is from 1 mm
Connect the cables with the Fast-on 6.3x 0.8 mm terminals (female).
Power and auxiliary cables are not included in the supply.
Liebert Hipulse E
WARNING
Q2-N.O.
Q2-COM
Q1-N.O.
Q1-COM
Q3/4-N.C.
Q3/4-COM
EXT. BYP
Table 4-1
2
.
(07/04)
UPS 2
X4-3
X4-4
UPS 1
X4-3
X4-4
X4-7
X4-8
UPS 2
X4-7
X4-8
Chapter 4 - '1+N' System
EXT. SW. OUT
EXT. SW. OUT
EXT. BYP
EXT. BYP
Page 4-9
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