Instruction Manual

DVC6000 SIS
September 2013
2-30
Table 2-1. Cable Characteristics
Cable Type
Capacitance
(1)
pF/ft
Capacitance
(1)
pF/m
Resistance
(2)
Ohms/ft
Resistance
(2)
Ohms/m
BS5308/1, 0.5 sq mm 61.0 200 0.022 0.074
BS5308/1, 1.0 sq mm 61.0 200 0.012 0.037
BS5308/1, 1.5 sq mm 61.0 200 0.008 0.025
BS5308/2, 0.5 sq mm 121.9 400 0.022 0.074
BS5308/2, 0.75 sq mm 121.9 400 0.016 0.053
BS5308/2, 1.5 sq mm 121.9 400 0.008 0.025
BELDEN 8303, 22 awg 63.0 206.7 0.030 0.098
BELDEN 8441, 22 awg 83.2 273 0.030 0.098
BELDEN 8767, 22 awg 76.8 252 0.030 0.098
BELDEN 8777, 22 awg 54.9 180 0.030 0.098
BELDEN 9501, 24 awg 50.0 164 0.048 0.157
BELDEN 9680, 24 awg 27.5 90.2 0.048 0.157
BELDEN 9729, 24 awg 22.1 72.5 0.048 0.157
BELDEN 9773, 18 awg 54.9 180 0.012 0.042
BELDEN 9829, 24 awg 27.1 88.9 0.048 0.157
BELDEN 9873, 20 awg 54.9 180 0.020 0.069
1. The capacitance values represent capacitance from one conductor to all other conductors and shield. This is the appropriate value to use in the cable length calculations.
2. The resistance values include both wires of the twisted pair.
CIRCUIT
UNDER
TEST
VOLTMETER
MILLIAMMETER
1 KW POTENTIOMETER
A6192-1/IL
Figure 2-25. Voltage Test Schematic
The following example shows how to calculate the
cable length for a Foxboro I/A control system (1988)
with a C
master
of 50, 000 pF and a Belden 9501 cable
with characteristic capacitance of 50pF/ft.
Length(ft) = [160,000 − 50,000pF]  [50pF/ft]
Length = 2200 ft.
The HART communication cable length is limited by
the cable characteristic capacitance. To increase
cable length, select a wire with lower capacitance per
foot. Contact your Emerson Process Management
sales office for specific information relating to your
control system.
2