In RTU Panel we are having several Analogue & Digital
Inputs /Outputs. We are recently facing some problems over
Analog inputs , which are not updating properly (But
Digital Input are updating normally) Can any one tell me
from where the problem is creating , we have checked PLC
CPU card, Analog Input card & we reconfigured ,But still
the issue is there.
Issue :
1. Sometimes Analog values are updating & sometimes not.
2. Analog values are not updating normally , showing some
wrong Values
3. Total dead (0 value)
Analog values are Level & flow measurement from the field
instruments.
(But in field the instruments are working normally &
Displaying the values normally in local display unit)
This problem we are facing in our Water Plant.
If any one experienced this same problem or having any
ideas related to our issue PLS send your valuable
Answers/Replies...
Answers were Sorted based on User's Feedback
Answer / dhaval jethva
Hi There........
As you have mention the problem,i can say that there is
definitely problem in two things (1) Scaling of that input
(2) Signal wire Coming from field instrument to your RTU
terminal.
If you dont find any problem above then do following Task
(3) if there is problem in only one channel of analog
terminal of RTU then By trial n error of by shuffling the
input you can verify where is the exact problem.
Please tel which i/p you are using Like is it 4 t0 20ma or
0 to 10 V from isolator of directly.
Regards
Dhaval Jethva
Is This Answer Correct ? | 2 Yes | 0 No |
Answer / rakesh kumar n
Reasons for this problem
-->In I/P there will be a problem in microprocessor,because
we use microprocessor for converting it into mA.
-->Check with another I/P,if you find the same problem,then
definitely cable Fault(loose contact in JC)
-->Check the loop test between the Junction box and Field
Instrument if it is correct, then check Junction box to
Control room is correct.
Thank you
Rakesh Kumar N
Is This Answer Correct ? | 2 Yes | 0 No |
Answer / manunath
hi....
there may be chance of two problem
1.problem with scaling of signal or
2.check the system earth ie AI module earthing...some
time it will create problem..
thank u
Is This Answer Correct ? | 1 Yes | 0 No |
Answer / guest
analog values are normally between the limits.... if we are
changing the inputs...depends on that the output is vary...but
it is there in between the limits
Is This Answer Correct ? | 0 Yes | 0 No |
Answer / mudassir
please check the cables scaling upto the RTU we face same
problem here in that i made only remove the cables clen them
and reconnect them then it works normal but in one that i
shuffle the AIS
Is This Answer Correct ? | 0 Yes | 0 No |
Answer / mudassir
hiiiiii this is because of scaling of input cables in the MR
side or your analog chanel are hang if you remove the
connection and connect it again then it shows normal den its
your analog card has a problem.
Is This Answer Correct ? | 0 Yes | 0 No |
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