2-14 Series 90-30 PLC Installation and Hardware Manual – August 2002 GFK-0356Q
2
Module Shield Grounding
In general, the aluminum PLC baseplate is used for module shield grounding. On some Series
90-30 modules, shield connections to the user terminal connector on the module are routed to the
baseplate through the module’s backplane connector. Other modules, such as CPUs 351, 352, 363,
364, and 374 require a separate shield ground. These are discussed in the next several sections.
Shield Grounding Information for CPUs with External Port Connections
CPUs with external port connections, the 351, 352, 363, 364, and 374 must have a separate shield
ground connection to provide shielding for these ports. Because the design of the ground
connection for the CPU351 and 352 is different from that of the CPU363, 364, and 374, each
grounding method is discussed in a separate section.
CPU351 and 352 Shield Grounding
The CPU 351 or 352 module must be connected to frame ground at the slot where it is installed.
Two methods are provided for making this ground connection. Each CPU comes with an EMC
Grounding Kit (44A737591-G01) that contains a ground wire, grounding bracket, and screws.
1. The connection from the CPU to frame ground can be made using the ground wire (part
number 44A735970-001R01) that comes with the module in the EMC Grounding Kit. This
wire has a stab-on connector on one end for connection to a mating terminal on the bottom of
the CPU, and a ring terminal on the other end for connection to a grounded enclosure. Where
the ring terminal contacts a painted enclosure panel, either a star lock washer can be installed
between the terminal and the panel to cut through the paint, or the paint can be scraped away
down to clean, bare metal to ensure a good contact. Note: The star lock washer method is
suitable for a shield ground, but not suitable for a safety ground.
MOUNT ON
GROUNDED
ENCLOSURE
USE 1 #6
MACHINE SCREW
STAB-ON
CONNECTO
44A735970-001R01
REMOVE PAINT UNDE
RING TERMINAL OR INSTALL
STAR LOCK WASHER BETWEEN
TERMINAL AND PANEL
CPU351 or 352
BOTTOM OF
CPU MODULE
#6 TAPPED HOLE
Figure 2-12. CPU 351 or 352 - Attaching Shield Ground Wire
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