Answer / faiyaz ahmad

As we all know, each and every thing has some resistance.Like wise,the resistance of the conductor increases with the length of the conductor.
2 wire- The RTD element's resistance will be calculated between 2 wires.i.e; positive & negative.In this measurement, the RTD output also includes the resistance of the 2 wires which we use to connect from RTD element to temperature transmitter.
3 wire- The RTD element's resistance will be calculated between one positive and two negative terminals.In this measurement, the RTD element's third wire is used to compensate the lead resistance of one neagative wire as both the wires get shorted and resistance of the two negative wires is approxiamately 0 ohms.But still the resistance of the positive wire will get added in the output which is almost negligible.
4 wire- This 4 wire measurement is used where we need almost
100% accuracy.The RTD element's resistance will be calculated between two positive and two negative wires.In this measurement,two positive wires will get shorted and two
negative wires will get shorted making the lead resistance of both the wires eliminated approxiamately.

Answer / raj7.eie

I dont think there is a thing called 3-wire.
2Wire means it has one supply line and one signal line.
4Wire has 2 supply line and 2 signal line.

what is the reset offset and control system in instrumentation

0 Answers   ABB,

---

Why ac supply load cell is used? Can we use the dc supply load cell?

0 Answers  

---

why bevelling is done in an orifice ?

4 Answers   ABB,

---

Please explain for RS 485 & RS 232 communication

1 Answers   Honeywell,

---

relation between flow and differential pressure.

7 Answers   ABB,

---

Explain Difference between Bech set and operating range of control valve

3 Answers  

---

Why thermo wells are used?

1 Answers  

---

wat are the interview questions asked in air india for post service engineer

1 Answers   AirIndia, Shree Renuka Sugars,

---

A pressure transmitter with a range of 0-100 bar.The accuracy of the instrument is 1% of upper range value? The pressure indicating transmitter is showing the system pressure is 50 bar. b. When you include the error, what is the minimum possible pressure in our fuel gas system? i. 49.5 bar ii. 49 bar iii. 1 bar iv. 0.5 bar We want to change the filter cartridge. We must depressure the fuel gas system. c. After we depressure the system in preparation for maintenance, the transmitter displays a pressure of +0.1 bar. At this time, what is the possible range of pressures in our fuel system? i. +0.099 to +0.101 bar ii. 0 to +0.2 bar iii. -0.1 to +0.3 bar iv. -0.9 to +1.1 bar

3 Answers  

---

why we use -ve voltage in vibration monitoring system.generally we use 4 to 20 mA as output of instrument then why we use voltage in vibration

2 Answers  

---

Explain the combusion chamber

0 Answers   IFFCO,

---

can we use a control valve without positioner

19 Answers  

---