20
6. Fixed Apparatus power circuit
connections
6.1 General directions
Make the connections using only the square terminals supplied
with the apparatus.
Select the conductor cross-section according to the operating
and short-circuit current of the installation.
Suitable supporting insulators sized to suit the electrodynamic
stress that may be produced by the short-circuit current of the
installation must be provided near the terminals of the fixed
version apparatus or enclosure.
6.2 Mounting the connections
Check that the connection contact surfaces are perfectly flat
and free from burrs, traces of oxidation or deformation due to
drilling or impact.
Perform the operations described in the table on the contact
surface of the conductor, depending on the conductive mate-
rial and surface treatment used.
6.3 Mounting procedures
Place the connections in contact with the apparatus terminals.
Fit a spring washer and a flat washer between the head of the
bolt and the connection.
Tighten the bolt, taking care not to subject the insulating parts
to stress (see table-tightening torque).
Make sure that the connections do not exert force on the ter-
minals.
In the case of cable connections, carefully comply with the
manufacturer’s instructions for terminating the cables.
Table of tightening torque
Screw
Tightening torque
M6
10 Nm
M8
30 Nm
M10
40 Nm
M12
70 Nm
Bare copper
Silver-plated copper
or aluminium
Bare aluminium
Clean with a fine file or
emery cloth
Clean with a rought
dry rag
Clean with a metallic
brush or emery cloth
Fully tighten and smear a
film of industrial vaseline
grease over the contact
surfaces
In case of tough
oxidation traces only,
clean with a very fine
emery cloth, taking
care not to remove the
surface layer
Immediately smear
a film of industrial
vaseline grease over
the contact surfaces
Interpose the copper-
aluminium bi-metal
with restored surfaces
between the aluminium
connection and the
copper terminal (copper
side in contact with
the terminal; aluminium
side in contact with the
connection)
If necessary,
recondition the
surface treatment
Figure 14. DS1 power connections
Provided
by
Northeast
Power
Systems,
Inc.
(NEPSI)
