6.4.7 Use of aluminum conductors
If you are using aluminum conductors, comply in addition with the following:
● Use only cable lugs that are suitable for connecting aluminum conductors.
● Immediately before inserting the aluminum conductor, remove the oxide layer from the
contact areas on the conductor and/or the mating piece, by brushing or filing.
● Then grease the contact areas immediately using neutral vaseline in order to avoid re-
oxidation.
NOTICE
Aluminum flow due to contact pressure
Aluminum flows following installation due to the contact pressure. The connection with the
clamping nuts can loosen as a result. The contact resistance would increase and the
current-carrying impeded; as a consequence the terminal box and the surrounding
components could burn. This could result in material damage to the machine or even in
total failure, which could in turn lead to indirect material damage to the system.
Retighten the clamping nuts after approximately 24 hours and then again after
approximately four weeks. Make sure that the terminals are de-energized before you
tighten the nuts.
6.4.8 Using single-stranded cables
NOTICE
High temperatures from induced eddy currents
With high currents and where several single-stranded cables are used instead of multiple-
stranded cables, high temperatures can result in the cable entry area due to induced eddy
currents. This can result in material damage or even a machine failure.
● After commissioning, ensure that the temperature limits of the connected power cables
are not exceeded during 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.
● Use a cable entry plate made of non-ferrous metal.
6.4.9 Internal equipotential bonding
Between the ground terminal in the terminal box enclosure and the machine enclosure, the
fixing screws of the terminal box serve as PE conductor connection.
Between terminal box cover and terminal box enclosure, the cover fixing screws serve as
equipotential bonding.
A special external ground conductor is only installed if, for example, flat seals are mounted
without additional support.
Electrical connection
6.4 Connection
SIMOTICS TN Series N-compact 1LA8
Operating Instructions 05/2016 73
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