Siemens SIROTEC Planning Manual page 39

Single-sided shield connection (special case)
The single-sided shield connection must be applied only for special cases (e.g.
only analog systems without digital technology):
· Single-sided connected line shields effect exclusively electrostatically against
low-frequency capacitive couplings and emissions.
·
At interferences due to external earth potential differences , despite an existing
equipotential bonding line between the components to be connected (e.g.
between the actual value transmitter and the testing circuit assembly), it may
be necessary in individual cases to connect the shield only on oneside with the
housing earth. For the improvement of the shield effect, the open shield side
can be connected in this case capacitively with the housing earth.
Shield connection with single-sided shield connection
·
The shield must be linked at the side at which the electronic reference earth is
connected to the device housing.
·
If both devices are potential-free, attach the shield on the receiver side.
·
If this housing connection exist on both devices, then a double-sided shield
connection is necessary.
Fig. 6-3
© Siemens AG, 2004. All rights reserved
EMC Installation Guideline – Planning Guide (EMV) – 03.2004 Edition
K1
Transmitter
with potential
reference
Potential formation here
One-sided connected shield with transmitter sided potential formation
Shield connection
(large scale)
Potential formation here
Wiring and Shielding
K2
Receiver
potential-
free
6-39