ABB hd4 Installation And Service Instructions Manual page 14

7.6. Fixed circuit-breaker power circuit
connections
7.6.1. General directions
– The connections must be made using only the squares-
terminals supplied with the circuit-breaker.
– Select the conductor cross-section according to the
operating and short-circuit current of the installation.
– Near the terminals of fixed version circuit-breakers or
enclosure, provide suitable support insulators dimensioned
according to the electrodynamic stresses that may arise
from the short-circuit current of the installation.
– Fit the isolating partitions if provided.
7.6.2. Mounting the connections
– Check that the connection contact surfaces are perfectly
flat and have no burrs, oxidation traces, or deformations
due to drillings or impacts.
– Depending on the conductive material and surface
treatment used, carry out the operations indicated in the
table on the contact surface of the conductor.
Bare copper
– Clean with a fine file or emery cloth.
– Fully tighten and 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).
14
Mounting procedures
– Place the connections in contact with the circuit-breaker
terminals.
– Interpose 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
terminals.
– In case of cable connections, carefully follow 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
Silver-plated copper or aluminium
– Clean with a rough dry rag.
– In case of tough oxidation traces
only, clean with a very fine emery
cloth, taking care not to remove
the surface layer.
– If necessary, recondition the
surface treatment.
Bare aluminium
– Clean with a metallic brush or
emery cloth.
– Immediately smear a film of
industrial vaseline grease over the
contact surfaces.