The instructions contained in this section refer
specifically to the use of aluminum cables with
this inverter. These instructions supplement the
specifications of the manufacturer of the termi-
nal blocks.
Handling aluminum conductors during installation work
The special properties of aluminum must be taken in to conside-
ration when using aluminum:
● Aluminum "flows", i.e. it gives way under pressure.
● A thin non-conductive oxide layer forms within a few minu-
tes on de-insulation, which increases the contact resistance
between the conductor and clamping point.
● The specific conductivity and hence the current carrying
capacity is approximately one third less than that of copper.
ATTENTION
Extreme temperature rise at the clamping
point
If the contact resistance between the aluminum
conductor and clamping point is too high, the
clamping point can become very hot and even
catch fire in extreme cases.
To ensure a safe and reliable contact,
always
perform the following work steps:
► Use a conductor cross-section at least one
number larger due to the lower current-
carrying capacity.
► Keep the installation location as free
as possible from moisture or corrosive
atmospheres.
► Connect the aluminum cables quickly.
► Mechanically clean the stripped end of the
aluminum conductor (using for instance
a knife blade to scrape off the oxide
layer), then immediately dip the aluminum
conductor into acid-fee and alkaline-free (=
neutral) Vaseline and straight away insert it
into the terminal block.
► Tighten the clamping screw in the clamping
body with the maximum permissible
tightening torque.
Instructions regarding selection and utilization of Al-Cu
compression joints
When using aluminum cables with Al-Cu compression joints
(e.g. from Klauke, Elpress or Mecatraction) and heat-shrink
tubing, observe the following instructions.
► Select compression joints suitable for the type of cable that
is used.
► Comply with the installation instructions issued by the ma-
nufacturer of the compression joints.
► Secure the cables with an external strain relief element.
Additional Al-Cu compression joints and heat-shrink sleeving are
required with non-sector-shaped, solid aluminum cables
► Use original tools from the manufacturer of the compression
joints for assembling the aluminum cables.
AC cabling using aluminum cables, compression joints and heat-
shrink sleeving
► The external diameter of the compression joints plus heat-
shrink sleeving must be smaller than the width of a clam-
ping point on the terminal block.
UKH 70 (M88H_122 CF)
UKH 150 (M88H_121 ST)
20,3
31
Width of a clamping point on the terminal block
► Pull the heat-shrink sleeving on so that the aluminum part
of the compression joint is completely covered.
Quick installation guide for solar inverter M88H RPI883M121300 RPI883M122300 EU V1 EN 5017414200_00 2019-11-07
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Special instructions for the use of aluminum cables
