Emerson Daniel 3818, Installation Manual

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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 Cable
resistance Cable Pull-up
resistance Total Maximu
m
frequency Sink Cable
voltage
drop
Length (2
Conductor
s) Capacitan
ce Resistance Resistance Frequency Current (2
Conductor
s)
(x1000ft) Ω nF Ω Ω (Hz) (A) VDC
0.5 16.8 10.00 1000 1016.8 5000 0.024 0.397
1 33.6 20.00 1000 1033.6 1000 0.023 0.780
2 67.2 40.00 1000 1067.2 1000 0.022 1.511
4 134.4 80.00 1000 1134.4 1000 0.021 2.843
0.5 16.8 10.00 500 516.8 5000 0.046 0.780
1 33.6 20.00 500 533.6 5000 0.045 1.511
1.7 57.12 34.00 500 557.12 5000 0.043 2.461
6.5 218.4 130.00 500 718.4 1000 0.033 7.296
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
• Pull-up voltage is 24 VDC
Installation manual Electrical Installation
3-9000-771 May 2019
Installation manual 41