3 Electrical installation
Topics covered in this chapter:
•
Cable length TTL mode
•
Cable length Open Collector mode
•
Grounding meter electronics housing
•
Conduit seals
•
Wiring and I/O
•
Security seal installation
3.1 Cable length TTL mode
The maximum cable length is 2000 feet when the Digital Output “TTL” mode is selected.
3.2 Cable length Open Collector mode
For the Digital Output “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.
Configurations for open collector frequency outputsTable 3-1:
Cable
Cable re-
sistance Cable
Pull-up
resist-
ance Total
Maxi-
mum fre-
quency Sink
Cable
voltage
drop
Length (2 Con-
ductors)
Capaci-
tance
Resistance Resistance Frequency Current (2 Con-
ductors)
(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
Electrical installation
Installation manual 45
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