Specifications

Theory of Operation
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31007715 6/2008
The Power Distribution Modules
Functions A PDM distributes field power to a set of Advantys STB I/O modules on the island
bus. The PDM sends field power to the input and output modules in a segment.
Depending on the PDM module you are using, it may distribute sensor power and
actuator power on the same or on separate power lines across the island bus. The
PDM protects the input and output modules with a user-replaceable fuse. It also
provides a protective earth (PE) connection for the island.
Voltage
Groupings
I/O modules with different voltage requirements need to be isolated from each other
in the segment, and the PDMs serve this role. Each voltage group requires its own
PDM
Standard
PDM Power
Distribution
A PDM is placed immediately to the right of the NIM in slot 2 on the island. The
modules in a specific voltage group follow in series to the right of the PDM. The
following illustration shows a standard STB PDT 2100 PDM supporting a cluster of
115 VAC I/O modules:
1 115 VAC sensor power signal to the PDM
2 115 VAC actuator power signal to the PDM
Notice that sensor power (to the input modules) and actuator power (to the output
modules) are brought to the island via separate two-pin connectors on the PDM.
The island layout shown above assumes that all the I/O modules in the segment use
115 VAC for field power. Suppose, however, that your application requires a mix of
24 VDC and 115 VAC modules. A second PDM (this time a standard STB PDT 3100
module) is used for the 24 VDC I/O.
115 V
DAI
PDM
DAI DAI
DAO
DAO DAO
NIM
1
2
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