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Introduction
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12
There are a variety of other status points that may be monitored: open door or window, high
water alarm, high temperature, main power, panic button for man at site, etc.
The RTU analog input range is 0 to 5 V
dc
, and the levels being monitored should be
electrically scaled to fall within this voltage range. Many sensing devices output 0 to 5 V
dc
.
However, some sensor outputs are 4 to 20 mA current loops, or an input may be using a 12-
volt power supply. The diagram below shows how to convert these two power sources into 0
to 5 V
dc
levels for the RTU (4-20 mA Loop would be converted to 1-5 V
dc
). There is a 249
Ω
resistor in the RTU that may be used to convert 4-20 mA to volts.
470 k
Ω
Analog
Input
12 Vdc
Power Supply
330 k
Ω
Analog
Input
249
Ω
4 - 20 mA
Loop
Figure 4. Common Conversion Circuits for 0-5 V
dc
Scaling
Содержание 1708
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Страница 8: ...Contents 025 9209K 8...
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Страница 60: ...Repair 025 9209K 60 MODEL 1700 SERIES ENCLOSURE OUTLINE 024 0057B...
Страница 61: ...Repair 025 9209K 61 MODEL 1700 SERIES ENCLOSURE INSTRUCTIONS 024 0056D Sheet 1 of 2...
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Страница 63: ...Repair 025 9209K 63 MODEL 1708 REMOTE TERMINAL UNIT SILKSCREEN 702 9439F...
Страница 64: ...Repair 025 9209K 64 MODEL 1716 REMOTE TERMINAL UNIT SILKSCREEN 702 9440F...
Страница 72: ...Appendix B 025 9209K 72...
Страница 80: ...Glossary 025 9209K 80...