NOTICE
Ground loop
The cable screen is connected to the load cell housing.
Make sure to use the PR 6021/08 or PR 6021/68S cable junction box (see
Chapter
11.2.4
), whose special technology prevents a ground loop.
6.2.1
Load cell cable
The load cell cables are inseparably connected to the load cells in the factory and their
individual resistance and temperature efect are equalized with the load cells.
Therefore, never shorten the cables, rather simply roll up the extra length and secure it.
The special sheathing material and the integrated strain relief with Kevlar thread ensure
extremely long service life even under diicult operating conditions.
However, despite the robust nature of the materials used, the cable should be protected
from excessive chemical and mechanical stresses. Preventing water from penetrating the
end of the cable is also important "life insurance" for the system.
6.3 Cable junction boxes
Special cable junction boxes are recommended for use (see Chapter
11.2.4
). They have
extremely high-quality screw terminals with high contact security and long-term stability
along with a special conduit as well as integrated elements for lightning protection.
The circuit board with its milled grooves provides extraordinarily high insulation
impedance, even in moist environments.
The special valve with a GoreTech semi-permeable membrane ensures permanent
pressure compensation during luctuating temperatures and weather conditions, and
efectively prevents water from penetrating.
NOTICE
Defective cable junction box due to penetration of water.
Special valve must not be removed.
6.3.1
Lightning protection
The load cell PR 6221 is equipped with a special SG that provides especially high
insulation values and extremely high dielectric strength.
The shielding was adapted to the cable junction boxes PR 6021/08 and PR 6021/68S and
ofers extremely high dielectric strength.
The cable junction boxes have lightning protection elements, each optimized to the
respective application. The accompanying conduit and switch are the result of extensive
tests at various high-voltage laboratories and universities and provide the optimal
lightning protection with a minimum retroactive efect on the measurement results.
The tests prove conclusively that the entire system must be considered as a whole,
including the load cell, junction box and the conduit and shielding to the device.
Insulation of only one element (load cell, junction box or device) leads to insuicient
protection or even to worse protection of the system as a whole.
6 Connection
Weighbridge Load Cell PR 6221
EN-23
Minebea Intec