Answer / sam

There are only three ways to wire any instrument in the
field. We called them two, three or four wire systems.
Loop powered is the most common and widely used everywhere
to connect the field instruments to PLC's or DCS.

2 wire = 1 wire Pos 24VDC (4 - 20mA signal)(loop Powered)
1 wire 0V

3 wire = 1 wire Pos 24VDC (Instrument supply V)
1 wire 0V (Common for supply and signal)
1 wire Pos 24VDC (4 - 20mA signal)

4 wire = 1 wire Pos 24VDC (Instrument supply V)
1 wire 0V (for supply)
1 wire Pos 24VDC (4 - 20mA signal)
1 wire 0V (for signal)

Also in 4 wire system:

4 wire = 1 wire Live 110VAC (Instrument supply V)
1 wire Neutral 0V (for supply)
1 wire Pos 24VDC (4 - 20mA signal)
1 wire 0V (for signal)

Good Luck

Why 4-20mA SIGNAL IS PREFERRED OVEA A 0-10v signal?

5 Answers  

---

Can we place a Control Panel in Hazardous area Group IIC ? If 'yes' then is there any approval required? If 'yes' then there is any specific IP rating or any standard required? If 'Yes' What is MOC of control panel?

2 Answers  

---

flow transmitter range is 0 -500 mmwcc but the transmitter shows 12 ma for o mmwc instead of 4 ma ...how to solve this problem when we apply 375 mmwc it shows 16 ma

3 Answers  

---

Dead weight tester & comparator for calibration , which is more accurate , what is the application.

1 Answers   Bapco Bahrain Petroleum Company,

---

Boiler flame scanner advantage?

0 Answers   Fluke, Petrochemicals, Tata Chemicals,

---

What is hook's law

4 Answers  

---

HI friends.I am Surya a BTech in Electronics and Instrumentation Engineering.I am going to appear Relince Industries Ltd all India writen test very soon. so plz help me by sendind the probable questions about my subject.My mail ID is surya.barik@gmail.com.

0 Answers   Reliance,

---

In Boiler Drum Level- Level control valve how can it tuning (PID)?

2 Answers  

---

What is surge in compressors? How to detect and control it?

1 Answers   DEWA,

---

what is span value and zero ? and how set ?

0 Answers  

---

What do you do as a Engineering person EPC for Sizing&Selecting Control Valve?

1 Answers  

---

Why went

9 Answers  

---