Grounding Your Installation
For grounding purposes, your PLC housing(s) should be mounted on a suitably
finished metal mounting plate capable of supporting its weight along with the other
modules in the installation. An aluminum mounting plate with a chromate finish
such as IRIDITE, ALODINE or OAKITE No.36 would provide a low frequency (AC)
safety ground path and a low impedance shield path for EMI/RFI.
If a metal mounting plate (the preferred method) is not feasible, all PLC housings
within each drop should be interconnected by a flat braided ground strap with a
minimum width of 1 inch. The ground strap should be short and installed without
loops and bends. Use stainless steel hardware including a flat washer to secure
the braid strap to the housing.
Regardless of the housing-to-housing method of ground interconnection, the en-
tire installation should be grounded by a 1” wide (min) flat, braided cable installed
between the the primary housing ground connection point and a suitable factory
ground. This ground strap should also be short and installed without loops and
bends. The bulkhead and rack mounting illustrations show the housing’s recom-
mended grounding point.
Power Supply Function (AC and DC)
The PLC’s come with a built-in power supply.
The 381 El385El480E/485E/485K
Controllers run on 97 through 276 VAC (47 to 63 Hertz) and 24Vdc. As shown on
Figure 9, Once connected, AC power is then switched ON/OFF with a front panel
rocker switch.
The PLC will also operate continuously on 24Vdc as its an alternate or exclusive
source. Figure 9 shows a primary power input connector for a customer supplied
24Vdc source. Once connected, DC power is then switched ON/OFF with a front
panel rocker switch.
26
System Planning
GM+3984-EDK
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