Siemens SIMOTICS XP 1MB5 SH400, Operating Instructions Manual, Page: 83 / 166

6.7.6 Use of aluminum conductors
If you are using aluminum conductors, then comply 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. Do this using a brush or file.
● Then grease the contact areas immediately using neutral Vaseline. This prevents a new
oxide layer from forming.
NOTICE
Aluminum flow due to contact pressure
Aluminum flows following installation due to the contact pressure. The connection using
clamping nuts can loosen as a result. The contact resistance increases, obstructing the
current from being conducted. This can result in fire and material damage to the machine
– or even in total failure, as well as material damage to the plant or system due to machine
failure.
● 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.
The tightening torques for the electrical connections of the terminal board and grounding are
listed in the Table (Page 155) under case A.
6.7.7 Minimum air clearances
After proper installation, verify that the minimum air clearances between non-insulated parts
are maintained. Be aware of any protruding wire ends.
Table 6-4 Minimum air clearance dependent on rms value of the alternating voltage U
rms
Rms value of the alternating voltage V
rms
Minimum air clearance
≤ 500 V 8 mm
≤ 630 V 10 mm
≤ 800 V 12 mm
≤ 1000 V 14 mm
≤ 1250 V 18 mm
Values apply at an installation altitude of up to 2000 m.
When determining the required minimum air clearance, the voltage value in the table may be increased
by a factor of 1.1, so that the rated input voltage range is taken into account during general use.
Electrical connection
6.7 Conductor connection
1MB5 SH 400/450
Operating Instructions, 05/2019, A5E45959221A
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