ABB UniSec Operation And Maintenance Manual page 7

D I S T R I B U T I O N S O LU T I O N S
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2. Design and manufacture
2.1 Construction of the switchgear
General aspects
When the UniSec units were designed, particular
attention was paid to increased operational reliability
and enhanced safety of personnel in the event of faults
due to internal arcs.
To improve the conditions of safety for the personnel
and for maintenance operations, the units have been
divided into separate compartments. These
compartments are designed to withstand very sharp
temperature and pressure rises caused by internal arc
faults.
2.2 Design conception of units and
2.2.1 Compartments
UniSec is a switchgear classified LSC2A/PM and
LSC2B/PM or PI (for units with withdrawable circuit
breaker), under regulation IEC62271-200.
Compartments
The unit is divided into the following compartments:
1. Busbar compartment
The air-insulated busbar compartment is situated on
the top of the unit and usually runs through the whole
switchgear. A measuring or isolating unit placed in the
middle of the switchgear divides the main busbar
compartment.
Figure 1 Compartments
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2
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3
and main components
switchgears
LSC2A
Tools must be used to open the busbar compartment
since it is designed as a "compartment with access
controlled by tools".
WARNINGS
The user must take safety measures when opening
the busbar compartment (this means that the
busbars must be in a de-energized state (without
voltage and earthed)
2. Switch-disconnector compartment
The three-position switch-disconnector is located
between the main busbar and cable compartments. Its
housing consists of a top half made of epoxy resin and
a bottom half of stainless steel and is filled with SF6
gas, with the electrical parts of the switch-
disconnector inside it. The bottom stainless steel part
forms a metallic partition between the busbar and
cable compartments. This partition makes the product
safer by improving protection against contacts.
WARNINGS
This compartment has been designed as an
"non-accessible compartment", it must not be
opened
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1
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7
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3
LSC2B
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6
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