Answer / janes

4-20mA Active : 2 wire device. same pair of wire is used
for the Power supply and Output 4-20 mA Signal.
4-20mA Pasive : 4 wire Device. Device having external power
supply -110 Vac / 230 Vac / 24 Vdc and generate the 4-20mA.

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0 Answers   Eskom,

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We do have a problem in the company that is one PT connected to PlC which is mean 1 out of 1 in PLC system we do have the PAHH is 55 mbar and PALL 8 mbar with a timer of 15 sec for the PAHH the problem started when PAHH goes more than the set point which is 55 it reached up to 71 but due to timer doesn't trip . We force it and we checked everything nothing there . We replaced the transmitter problem still there the reading goes more than the 55 bar the range for transmitte is 0- 60 mbar . So we did loop check , aculaizing valve , wiring all are okay . What the possible causes for this ???

2 Answers   National Petrochemical Company,

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2 Answers   Jindal,

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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...

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why r using 250 resistances

6 Answers   Sabic, Samsung,

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why we are using 4-20ma why cant we use 4-40ma

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4 Answers   HCL, Hindustan Zinc,

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