27
2
1
7.7. Earthing
For the fixed version circuit-breaker, carry out
earthing by means of the special screws marked
with the relative symbol. Clean and degrease the
area around the screw to a diameter of about 30
mm and, on completion of assembly, cover the
joint again with Vaseline grease.
Use a conductor (busbar or cord) with a cross-
section conforming with the Standards in force.
7.8. Connection of the auxiliary circuits
Note: the minimum cross-section of the wires
used for the auxiliary circuits must not be less
than the one used for the internal cabling. Fur-
thermore, they must be insulated for 3 kV test.
Fig. 10
Fig. 10a
7.8.1. Fixed circuit-breaker
Connection of the circuit-breaker auxiliary circuits
must be made by means of the terminal box (1)
(fig. 10) mounted inside the circuit-breaker and
the cables must pass through the connector (2).
Outside the connector, the cables must pass
through a suitable metal protective cover (pipe,
wiring duct, etc.) which must be earthed.
To prevent the cabling wires outside the circuit-
breaker (provided by the customer) accidentally
coming into contact with moving parts and there-
fore damaging the insulation, it is recommended
to position and fix the cables as indicated in fig.
10a.
Before removing the operating mecha-
nism cover to access the terminal box,
check that the circuit-breaker is open
and the closing springs discharged.
!
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