Connection Of Sensors - Siemens S5-155U System Manual

9.3.8

Connection of Sensors

Connection of current or
voltage sensors
Equipotential bonding
Sensor,
Isolated
+
U E
-
Figure 9-6 Measuring Circuit with Equipotential Bonding Conductor for the 460 Analog Input Module
System Manual
C79000-B8576-C109-03
Observe the following information when connecting the sensors.
With isolated sensors, it is possible for the measuring circuit to
develop a potential with respect to ground which exceeds the
permissible potential difference U
individual modules). To prevent this, you must connect the negative
potential of the sensor to the reference potential of the module
(0 V bus).
Example:
Temperature measurement on a busbar with insulated thermocouples
In the worst case, the measuring circuit can develop an excessively
high potential on account of a static charge or contact resistances. This
must be prevented with an equipotential bonding conductor.
The permissible potential difference (U
0 V bus must not be exceeded.
Depending on the system or type of sensor, the potential difference
must be kept in the permissible region with equipotential bonding.
Analog Input Module
M +
MUX
Range
M -
Card for
4 Inputs
Equipotential Bonding Conductor
The 460 Analog Input Module
(see maximum values of the
CM
) between the inputs and the
CM
A
#
D
0 V Bus
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