AVL F-FEM-DAC User Manual

Grounding and Shielding
F-FEM-DAC
F-FEM-DACF-FEM-DAC
F-FEM-DAC
Operating Manual
17
3.3 Grounding and Shielding
3.3.1 Grounding
For grounding, the following must be considered:
n Prevent dangerous contact voltage at electrically conductive
parts;
n Parasitic currents must be led back to their source of origin via the
shortest route possible.
This requires low grounding resistance and compliance with the high
frequency rules regarding installation, wire types and contacting.
The F-FEM-DAC is electrically isolated from the 24 V DC supply. All
analog outputs are electrically isolated from each other and from the
system. The ground wires of the individual outputs can be connected to
the ground of the measuring system (please see pin assignments X5 –
X8). For safety purposes, the case is connected to the ground via a PE
and via the DIN rail (to avoid radio frequency interferences). The PE is
carried in the power supply cable.
If several F-FEM clusters are connected with each other in a network,
every cluster should be grounded with low inductance to the ground of
its local signal source.
If an IEEE1394 interface is used, ground wires must be used between
the individual F-FEM clusters as well as between the first cluster and
the host system (PUMA, PC). Potential equalization is ensured by the
PEs, which are carried in the supply lines. The ground wires minimize
the effects of the ground loop between the different ground potentials
of the network (please refer to Fig. 9 "Grounding when using standard
cabling" on page 19).
To avoid ground loops completely, a fiber optic link can be used to
connect the clusters or to connect PUMA and the first cluster (please
refer to Fig. 10 "Grounding when using a fiber optic link" on page 20).
In this case, a compensatory current over the ground wires and over
the supply wire shielding is possible.
If the ground of the engine in the test cell and of the host system have
to be separated (e.g. due to too great a distance or ground loops), the
F-FEM cluster which is assigned to the engine in the test cell should
have its own 24 V power supply. Then the shielding of the power
supply lines of the F-FEM cluster must be connected via a capacitor to
the same PE to which the 24 V power supply is connected. The ground
wire must then be clamped to the 0 V output of the 24 V power supply
(please see Fig. 11 "Grounding when using a fiber optic link and split
grounds" on page 21).

AVL F-FEM-DAC Specifications

General

Brand	AVL
Model	F-FEM-DAC
Category	Measuring Instruments
Language	English