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Reference Manual
00809-0100-4860, Rev BC
Section 2: Installation
January 2013
Installation
Figure 2-10. Power Supply Load Limitations
Note
R
loop(max)
in the equation above refers to the total loop load resistance. Technically, the total
loop load resistance is the sum of the loop load resistor, signal wiring resistance, and if
applicable, any intrinsic safety barriers. In a typical installation, the loop load resistor will largely
determine the total loop resistance. In some installations, depending on signal wire gauge and
signal wire length, and/or any IS barriers, the additional resistance may need to be accounted
for.
To minimize noise pickup on the 4-20 mA signal and any digital communications signal:
Twisted pair wiring is recommended.
Shielded signal wire is preferred.
For high EMI/RFI environments, shielded signal wire is required.
To ensure proper operation, wiring should be:
24 AWG or larger.
Less than 5000 ft. (1500 m) in length.
Gage Number A.W.G.
Ohms per 1,000 ft (305 m) at 68 °F (20 °C)
Equivalent
14 2.525
16 4.016
18 6.385
20 10.15
22 16.14
24 25.67