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10) PROTECTION AGAINST ELECTRICAL NOISE
10.1
The signal outputs from the load cells are always low and they may be seriously spoilt by
the external electrical disturbances.
The main cares to be taken are the following:
10
.2
For the connection cell-signal conditioner always use cable with braiding shield 100%.
The cell and the cable have to be set up far from electric motors, power switches, etc. The
cables have to run into separated raceways.
10
.3
The braiding shield is insulated from the cell body and it has to be grounded at the
electronics side only.
When the screen is insufficient, the cable can be put in a tube of normal iron (paramagnetic,
with low percentage of carbon) (= good electromagnetic screen) with an external insulating
sheath to avoid to pick up the stray currents of the metal structures connected.
10
.4
When mating connectors are needed along the cable, the shield has to go through a pin and
not through the metal shell of the connector and the connector has to be insulated and
covered by plastic tape.
10
.5
Avoid to use earth nets of industrial plants, always rich of electrical disturbances, but use
separated ground taps.
The ground tap has to be at the centre of all the ground leads of the instrumentation only.
Never connect the ground in series but each directly connected to the ground tap as a sun (=
ground tap) with separated planets (= the instruments).
10
.6
Follow all the local laws imposed for electrical connections and for the earth connections.
10
.7
To satisfy to the EMC normative it is imposed to connect the body of the transducer and the
shield of the cables to a good earth, without disturbances, as for the CE mark.
Содержание 500QD Series
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