HBK Z6M, Mounting Instructions, Page: 15 / 56

13
Z6/M
CONNECTION
Electrical and magnetic fields often induce interference voltages in the measurement
circuit. Therefore:
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use shielded, low‐capacitance measurement cables only (HBK cables fulfill both con­
ditions)
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do not route the measurement cables parallel to power lines and control circuits. If
this is not possible, protect the measurement cable with steel conduit for example
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avoid stray fields from transformers, motors and contact switches
8.1 Connecting several weighing modules in parallel
Load cells can be wired in parallel by joining the load cell cable core ends of the same
color. In this case the HBK range offers terminal boxes of the
VKK... series. The output
signal is then the average of the individual output signals.
CAUTION
Overloading of an individual load cell cannot then be detected from the output signal.
8.2 Connection using four‐wire circuitry
In the event of connections to amplifiers using four‐wire circuitry, the cores bl (blue) and
gn (green) should be connected together, as should bk (black) and gr (gray). The follow­
ing deviations occur in the case of cable of original length (3 m): Sensitivity -0.2 % and
temperature coefficient -0.01 %/10 K.
8.3 Cable extensions
Extension cables must be shielded and of low capacitance. We recommend the use of
HBK cables, which satisfy these requirements.
With cable extensions it is important to ensure that a good connection is provided, with
minimum contact resistance and good insulation.
When using six‐wire circuitry, the effects of resistance changes in the extension cable are
compensated. If you extend the cable using four‐wire circuitry, the sensitivity deviation
can be rectified by adjusting the amplifier. However, temperature effects are only be
compensated when operating with six‐wire circuitry.
Route the load‐cell connection cable so that any condensed water or dampness forming
on the cable can drip off. It must not be able to reach the load cell. In addition ensure that
no dampness can penetrate the open ends of the cable.