Siemens 1LA8 Series Operating Instructions Manual page 14

Direction of rotation
Connection of the power cables in the phase sequence
L1, L2, L3 to U, V, W results in a clockwise rotation. If
two of the connections are swapped then the resulting
direction of rotation is counter-clockwise (e.g. L1, L2,
L3 to V, U, W). On motors, which are only allowed to
run in one direction, the rating plate shows an arrow,
which indicates the permitted direction of rotation,
and it also specifies the terminal connections for the
required phase sequence.
Direction of rotation of the motor when looking at the drive
end
Note
These restrictions in terms of the direction of rotation
relate to the particular type of motor design and result,
for example, from the use of unidirectional fans. Any
restrictions in terms of the direction of rotation
resulting from the installation itself are not shown in
the information on the rating plate and need to be
considered separately when making the connections.
Connecting using cable lugs
When using cable lugs to make the connection, the
choice of cable lug size must match the required
conductor cross-section and the bolt size. A sloped/
angular arrangement is only permitted provided the
required air insulation gaps are met. Remove the
insulation from the conductor ends, so that the
remaining insulation is almost long enough to reach
the cable lug.
Note
The current-carrying capacity of the connection is
guaranteed using the CuZn contact nuts. These nuts
must not be replaced with parts manufactured from
different materials.
Connection without cable lugs
The design of the terminals makes it possible to
connect fine-wire conductors without the use of wire
end ferrules. Wire end ferrules may only be used, if
these are attached, before connecting-up, using the
correct, current-carrying compression technique.
Notice
If the terminal link is used, the current-carrying
connection is guaranteed using CuZn contact nuts.
These nuts must not be replaced with parts
manufactured from different materials.
Aluminum conductors
If aluminum conductors are connected, we
recommend removing the oxide coating layer using a
brush or file prior to inserting them in the clamps. The
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conductors should then be immediately greased using
neutral Vaseline in order to prevent reoxidation.
Notice
Aluminum flow is likely to occur after the conductors
have been connected due to the contact pressure. This
should be compensated for by re-tightening the
clamping nuts after approximately 24 hours and then
again after approximately 4 weeks.
Use of single-stranded cables
If high currents occur when using several single-
stranded cables instead of multiple-stranded cables for
three-phase supply cables, high temperatures can be
generated at the materials around the entry points to
the terminal box as a result of eddy currents. Once the
system has been taken into operation it is therefore
necessary to check that the temperature limits of the
connected power cables are not exceeded in
operation.
This temperature effect can be reduced by altering the
conditions at the entry points or by using modified
cable entry plates after consultation with the
manufacturing plant.
Cable entry and routing
Connecting cables and in particular the PE ground
conductor in the terminal box should be laid out in an
open arrangement, and they should preferably have
spare length to prevent chafing of the cable insulation.
Auxiliary cables fed in externally must be routed
separately from the main cable and secured. Elements
with cable ties are located on the floor of the terminal
box next to the walls for this purpose.
Screw-type cable connections should normally be used
(not included in the delivery scope). In special cases
the connecting cable is sealed at the cable entry point
using a cutout seal insert and is fastened using a strain
relief device. The strain relief device can either be
located in the terminal box or externally.
We recommend the following procedure:
• Cut out the seal insert in such a way that its
opening is 1 to 3 mm smaller than the cable
diameter. If the cable diameter is too small, this
should be increased by applying a layer of suitable
sealing tape around the conductor.
• After inserting the seal, make a termination to
match the cable and connect an earthing cable to
it. If the cable has external armoring, do not route it
directly into the terminal box, but just up to the
strain relief device, which in this case should also
be fitted externally. This prevents moisture from
penetrating into the terminal box.
• Unscrew the upper section of the tension relief
device and release the mounting screws for the
lower section. Insert the cable with seal insert into
the gland opening. When the cable is positioned
concentrically inside the gland opening, screw the
tension relief clamp together and appropriately
retain it.