Control Cables; Earthing The Switchgear - ABB UniSec Manual

5.2 Control cables

The internal cables between units are easily laid through open-
ings in the side walls of the auxiliary circuit compartment.
Depending on the delivery times, there are two different proce-
dures for supplying the connection cables of the units:
• Cables not included
• Cables supplied rolled in a bundle in the auxiliary circuit
compartment.
Table 6 gives the correct torques for the terminal blocks.
Terminal Blocks
Width of terminal Cross-Section of
box (mm) cable (mm
5 0.2-2.5
6 0.2-4
8 0.5-6
Table 6. Terminal Blocks
The options available for control cable entry are:
• Side duct at both ends of the switchgear.
• A duct can also be placed on the roof of the switchgear to
support the incoming cables, for example, from an overhead
cable ladder.
Figure 124. Control cable entries
Tightening Torque
2 ) (Nm)
0.4-0.6
0.5-0.8
0.8-1

5.3 Earthing the switchgear

Each unit is fitted with earthing busbars that run longitudinally
in the lower front part of the unit. These busbars must be
connected together as shown in chapter 5.3.1. The station
earthing system must be connected to the end unit of the
switchgear. If the switchgear consists of more than 8 units, it
is advisable to connect the station earthing system to both end
units. The external station earthing connection point inside the
unit is shown in Figure 128. All the apparatus is connected to the
earthing busbar via the switchgear housing. The interconnection
between units is capable of carrying the rated short-time and
peak withstand current for the earthing circuit.
5.3.1 Installing the earthing busbar
Installation operations are as follows:
a) Unscrew the right-hand screw (when there is another unit on
the right side) and loosen another two screws. Then move
the busbar towards the adjacent unit on the left.
Figure 125. Busbar moved towards the adjacent unit on the left
b) Move the busbar from the unit to the right (when there is
another unit on the right). Add the screw on the right and
screw up all the screws with the correct torque.
Figure 126. Busbar moved from the adjacent unit to the right
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