114
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7. Operation of the switchgear
Isolation truck
The isolation truck allows the switchgear top and
bottom contacts to be connected directly.
Connection is made extremely safe by using the
poles of the HD4 circuit-breakers to insulate the
connection bars from the external environment.
In the incoming / outgoing panels, it connects the
main busbar system to the power cables, whereas
in the bus-tie panels, it connects to the two sides
of the busbar system.
This truck is used in the UniGear switchgear to
make incoming / outgoing panels without circuit-
breakers in radial networks, to make cable
connections between two switchgear panels
placed in front of each other, and for constructing
interconnection panels and creating bus-tie-riser
panels with double insulation (in this case, both
the panels are made from bus-ties, the first fitted
with a circuit-breaker and the other with an
isolation truck).
Earthing and short-circuiting with Testing and
Earthing truck
• Isolate the area to be earthed and secure it
against reconnection
• Carefully follow all safety regulations
• Remove the withdrawable circuit-breaker
part from the relevant switchgear panel
• Secure the shutter in front of the live contact
pins by means of the padlock. Screw on the
Testing and Earthing truck 9 (Figure 187)
actuating bars 4 as follows: To the top
position for opening of cable compartment
shutter and to the bottom position for
opening of busbar compartment shutter.
• Further screw on the Testing and Earthing
truck insulating plate 1 with three removable
bushings as follows:
- Contact arms 3 in the bottom position
for earthing of cable output feeder
- Contact arms 3 in the top position for
earthing of busbars
• Insert the Testing and Earthing truck into the
test / disconnected position and then move
it into the service position with the hand
crank
• Using a high voltage tester, check that the
contact pins 6 of the earthing module are
definitely off-circuit.
• Withdraw the Testing and Earthing truck
back into the test / disconnected position
• Mount a complete short circuit link 7 on the
Testing and Earthing truck. Connect one end
of earthing cable 10 under one of three
screws M12, with which short circuit link is
connected to contact pins. Connect the
second end of this cable to the earthing
terminal in the panel.
• Insert the Testing and Earthing truck with
short-circuit link mounted and earthing cable
returned from the test / disconnected
position into the service position in the panel
with hand crank. For safety reasons, insert
the Testing and Earthing truck only with the
circuit- breaker compartment door closed
and with door catches locked.
• Display earthing warning label on the
switchgear panel door
• Secure neighboring areas to prevent
inadvertent contact with live parts (e.g.
feeder cables).
The procedure for removing earthing is the same,
only in reverse order.
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