why we use 4-20 mA for calibration of the instruments.why we cant use 0-20 mA?

5 Answers  

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what is exact time to study dcs and plc cources

1 Answers  

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There are two chlorination tonners both are connected to two pressure swithes and the pressure switch is connected to SOV which operates the valve to changeover the tonner selection i.e if pressure one tonner goes low the other tonner should come in line if it is inautomatic selection design a circuit using relays ?

1 Answers  

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Instrumentation Safe Guarding test. How to determine the interval time of the test. eg:Halfyearly,Every year,Every three years etc.

1 Answers  

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What is the difference between HMI,SCADA and MMI,not abbrevation?

7 Answers   HCL,

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in a power plant main steam flow is volumetric or mass flow? is it required compensation?

1 Answers   Wartsila,

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what will the sending unit in the fuel gauge utilizes?

1 Answers  

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I have a problem with a valve (air to close). When it is fully closed and try to open 1% it doesn't responce till 3% open suddenly more than 3% then back to 3%. I tried to tune positioner then removed it, the problem still exist. Any idea

3 Answers  

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What is close loop ?

1 Answers   College School Exams Tests, GMR,

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I have energy meter for educational project having 0.5s class but my friend need 0.2s class meter , which one is good for that purpose and what is the actual difference of that two classes , need very easy example also.??

1 Answers   BBS,

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what is upstream and downstream in liquid flow?

6 Answers   Thermax,

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plc trouble shootings?

3 Answers  

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