Reference Manual V1.19 Software Versions 4.xx
003R-682-119 Page 17
3.11. Connecting Shields
To obtain full EMC or for RFI immunity, cable shields MUST be connected to the earth lug on
the rear of the instrument.
Figure 14 illustrates an example of possible connections. Also shown are the connecting
cables restrained using cable ties fastened around the cable strain relief anchors.
Figure 14: Cable Shield Connection
3.11.1. Cable Shield Connection and Earthing
• Care should be taken when connecting shields to maximise EMC or RFI immunity and
minimise earth loops and cross-talk (interference) between instruments.
• For full EMC or for RFI immunity, termination of the cable shields at the earth lug is very
important. The earth lug of the instrument must be separately connected to ground
potential via a reliable link.
• The instrument should only be connected to earth via a single reliable link to avoid earth
loops.
• Where each instrument is separately earthed, interconnecting cable shields should be
connected at one end only. This also applies to communications cable shields in Ring
Networks, refer to Short Ring Network and Long Ring Network connections under ‘RS-
232 Serial’ pages 12 and 13.
• Caution: Some load cells connect the cable shield directly to the load cell (and therefore
the scale base). Connection of the load cell cable shield in this situation may be site
specific.
3.12. Regulatory Sealing Requirements
To comply with regulatory sealing requirements for each instrument, (i.e. to ensure instruments are
not accidentally or deliberately tampered with), it is important that proper sealing procedures be
adhered to. Refer to Appendix - Trade Sealing page 63 for more information.
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