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Installation manual
00825-0100-3812
3
Electrical Installation
3.1
Cable length TTL mode
The maximum cable length is 2000 feet when the "TTL" mode is selected.
3.2
Cable length Open Collector mode
For the "open collector" mode, the maximum cable length depends on the cable
parameters, pull-up resistance used, the maximum frequency to output, and
frequency input parameters being driven. The following table provides estimated
cable lengths for different pull-up resistor values and different Max Frequency
settings in the meter using the following cable parameters. The table also
provides an estimated cable voltage drop which indicates how much voltage will
be across the cabling and effectively indicates to what voltage level the frequency
input can be pulled down to by the frequency output.
If the voltage drop is higher than the voltage required for the frequency input to
see a low state, then the configuration will most likely not work for your system.
Performance of frequency outputs will vary from this table with setup and
frequency input being driven.
Table 3-1: Configurations for open collector frequency outputs
Cable
Length (2
(x1000
ft)
0.5
1
2
4
0.5
1
1.7
6.5
The 22 AWG wire characteristics are as follows:
•
Capacitance = 20 pF/ft or 20 nF/1000 ft (between two wires)
•
Resistance = 0.0168 Ohms/ft or 16.8 Ohms/1000 ft
Installation manual
Cable
Cable
resistance
Capacitance Resistan
Conductors)
Ω
nF
16.8
10.00
33.6
20.00
67.2
40.00
134.4
80.00
16.8
10.00
33.6
20.00
57.12
34.00
218.4
130.00
Pull-up
Total
Maximu
resistan
m
ce
frequen
cy
Resista
Frequen
ce
nce
cy
Ω
Ω
(Hz)
1000
1016.8
5000
1000
1033.6
1000
1000
1067.2
1000
1000
1134.4
1000
500
516.8
5000
500
533.6
5000
500
557.12
5000
500
718.4
1000
Electrical Installation
January 2023
Sink
Cable
voltage
drop
Current (2
Conductors)
(A)
VDC
0.024
0.397
0.023
0.780
0.022
1.511
0.021
2.843
0.046
0.780
0.045
1.511
0.043
2.461
0.033
7.296
43
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