Emc Protection - HBM RTN Mounting Instructions

5.5

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 less than 1 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
EU directives 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 deviations can be up to 0.05 %, based on the
full scale value. These surges in plants are caused by lightning strikes or
switching operations in power circuits. This is particularly evident with cables
over 30 m long or if the equipment is used outdoors. Customers should take
additional precautions in these cases.
Please note:
S Connect the whole surface of the connection cable shield to the shielding
housing of the electronics. If using several load cells, connect the shields to
the whole surface of the junction box (grouping of transducer signals, e.g.
type VKK2 from HBM). From there, connect the measurement cable for the
electronics to the whole surface of the junction box and the whole surface of
the shielding electronics housing.
S The connecting cable shield 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.
Important
Potential equalization is specified for applications in potentially explosive
atmospheres.
RTN
A01153_03_Y00_01 HBM: public
Electrical connection
15