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4.1.3
Parallel connection (option)
Only single point load cells with an aligned output (nominal (rated) sensitivity and output
resistance) are suitable for parallel connection. Many of HBM's single point load cell
types are available with this option.
4.1.4
EMC protection
Electrical and magnetic fields often induce interference voltages in the measuring circuit.
To ensure reliable measurement, however, the transducer must be able to transmit signal
differences of a few μV to the analysis unit without interference.
Planning the shielding design
Due to the numerous application options and differing local constraints, we can only
provide you with general information on correct connection. The shielding design suitable
for your application must be planned locally by an appropriate specialist.
HBM load cells with shielded, round cables are EMC-tested in accordance with the
EU Directive and bear the CE mark. Voltage surges as per EN 61000-4-5 can give rise to
deviations from the load cell's specified accuracy. These surges in plants are caused by
lightning strikes or switching operations in power circuits, for example, and disappear
again when interference is no longer active. This is particularly evident with cables over
30 m long or if the equipment is used outdoors. Customers should take additional pre
cautions in these cases.
Please note:
S
Connect the connecting cable shield all over the surface of the shielding electronics
housing. When using several load cells, connect the shields all over the surface of the
junction box (combination of transducer signals, e.g. type VKK2 from HBM). From
there, connect the measurement cable for the electronics over the surface of the
junction box and the shielding electronics housing.
S
The shield of the connecting cable must not be used for discharging potential
differences within the system. You must therefore lay sufficiently dimensioned
potential equalization lines to compensate for possible potential differences.
S
Use shielded low-capacitance measurement cables only (HBM cables fulfill these
conditions).
S
Do not route measurement cables parallel to electric cables, especially power lines
and control circuits. If this is not possible, protect the measurement cable, for
example with steel conduits.
S
Avoid stray fields from transformers, motors and contact switches.
4.2
SP4Mi IO-Link
Please ensure that the inline amplifier and load cell are on the same electric potential, to
prevent any compensating currents via the cable shield.
The module has a short-circuit proof design but is not protected against overvoltages.
SP4M, SP4Mi
ELECTRICAL CONNECTION
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