Answer / carl_ellis

The minimum required loop voltage depends on the voltage needed to drive 20ma (or 21.5mA if fail-safe high is used) through the total loop resistance.

Even if the power supply voltage sags/drops slightly, it is still possible that the loop will function properly, because it depends on the actual loop resistances and the lift-off voltage required by the transmitter

If there is not sufficient loop voltage, it will become apparent when the transmitter fails to go above a certain milliamp output, because there is insufficient voltage to drive more current through the loop's total resistance.

In some cases of low loop voltage, a field transmitter will cycle on and off, re-initializing each time it fails to push sufficient current because it is voltage-starved.

If the loop wiring is sized properly, then a voltage drop is likely due to
- a bad connection in junction box
- in some cases a ground loop from damaged wire insulation
- adding too many additional loads - more transmitters than the power supply is rated for
- failing power supply
- adding another device in series in the loop, like an indicator, recorder, or I/O module input that pushes the total loop resistance too high. Carl Ellis
Measure First

Answer / vinay

distance betwn. control rm. and transmitter may be larger or much as much recmmnd. 



Sol:-

   Use the amplifier or isolator in btwn them (rm. to tx.)

why we are using orfice plate? then difference between orfice 7 nozzle plate?

1 Answers   Flour Tech Engineers (P) Ltd,

---

How does SmartPlant Instrumentation interface with physical design (3D modeling)?

0 Answers  

---

how to calibrate level transmitter

2 Answers   Reliance,

---

What is the use of GMV in turbine?

0 Answers   Hamsco, Maruti Suzuki,

---

you must show the examples application and give at least 4 types of transducer/sensors that can minimize the failure during the manufacturing of the resistors.

0 Answers   DEWA,

---

---

What is instrumentation measurement?

0 Answers  

---

What are the cable come out from the paddle type flow sensor.and how is further connections

1 Answers  

---

Boiler flame scanner advantage?

0 Answers   Fluke, Petrochemicals, Tata Chemicals,

---

what is the difference between sinking and sourcing inputs and also what are there applications?

2 Answers  

---

can you provide me full detail about instrumentation in ONGC??

0 Answers   BRML, ONGC,

---

what is the difference between 2 wire and 3 wire RTD- application wise,cost effectivity?

2 Answers  

---

if differential pressure created by orifice falls below vapour pressure of liquid flowing through it what will happen

1 Answers   BARC,

---