Answer / carl_ellis

The 2 wire transmitter, DC power supply and the load (some
receiver, an analog input on a
PLC/DCS/Controller/recorder/indicator) are wired in series.
The installer 'gets them in the same path', an electrical
series circuit.

The transmitter uses about 3.5-3.6 mA of current as power to
run its own electronics that excite and/or read the sensor,
interpret the sensor's signal and create a scaled output.

A 2 wire transmitter acts like a variable resistor, or
transistor, in that it regulates its internal resistance so
that the output is scaled 4.0-20.0 mA, proportional to the
process variable it is sensing, with the loop current the
ranging 4-20mA.

The power supply voltage must be high enough to drive 20mA
(21.xmA if upscale failsafe is used/selected) through the
load (the input's resistance, wire resistance, any stray
resistance (terminal block). 24Vdc power supplies are the
most widely used power supplies, but most 2 wire
transmitters can operate with power supplies up to about
32-36 volts DC.

Carl Ellis
Measure First

Why humidity limit is 30 to 55 % for raw material storage?

1 Answers  

---

What is meant by calibration

5 Answers  

---

What is the difference between HMI and Scada?

4 Answers   Schneider,

---

What is the relation between electronics & instrumentation

2 Answers  

---

radial & axial vibration sensor output voltage is ac or dc volt?

8 Answers   Vedanta, Voltech,

---

defination of radial vibration?

0 Answers   EE Limited, MNC,

---

What you mean by multi stage control vavles?

0 Answers  

---

wt is cold junction compensation

1 Answers  

---

Good Evening all.My question is - For a feed water line to an equipment if i need to measure the flow we will use orifice /magnetic/vortex depend on cost/spec.If i need to measure a ''Alarm''signal and ''Interlock'' from one point i think we can use orifice type in one location with 2 different tapping points - one for alarm and one for an interlock to flow valve..If in case i need to have both these signals(Alarm & interlock) from magnetic flow meter,is it possible??will 2 seperate sensors will be located inbuilt r we can program it ??..i thk we can have one transmitter with these 2 signals...need to know any technical issues are there?pls clarify

3 Answers  

---

what is meant by cold junction compensation. where it is used.

1 Answers   SRACO,

---

can anyone tell me about the basic concepts to consider before to start a PLC panel wiring

0 Answers   ABB,

---

HOW CAN I CONNECT ROSEMOUNT 3300 LEVEL TRANSMITTER TO Allen-Bradley SLC500

1 Answers  

---