Answer / tang

Because we want to know the "life zero".
Life zero is a condition where there's a signal when the process is at 0%. For an example if we use 0mA instead of 4mA, we might don't know either the process is really 0% or the measuring unit is faulty(that will also indicate 0mA).

Answer / venkadesh

because the transistor operating region range is 4-20 ma,these in between range is transmitter working in safe level

What is electronics?

6 Answers   ITC Infotech,

---

what is meant by control valve sizing?

3 Answers  

---

What skill/s does the Instrument Technician has?

6 Answers  

---

I have a steam flow DP transmitter that has output swinging. Steam valve is in manual.I have good steam pressure. The impulse lines have steam tracing on them. The steam tracing has a hole in it that is blowing raw steam on the high side impulse line only. Could this be causing the swinging?

1 Answers   Honeywell,

---

What is the relationship between GAIN and PROPORTIONAL BAND.

1 Answers   Kharafi National, Sabic,

---

what is the difference between(Flame proof/Explosion proof)& Fire proof instruments.Both are same or different & if different in which way because the transmitter which have approved ATEX flame proof enclouser but it use PTPE O ring & PTFE Head Gasket,so its (fire safe/fire proof)????????

4 Answers  

---

what is the function of a zener diode ?

2 Answers   Honeywell,

---

What are the interlocks we have to check during the start up of LP/HP compressor?

0 Answers   Hamsco,

---

1. How many output signals do wew have in process control? 2. Could you write down the names of the pre-commissioning and commissioning stage test instruments and explain them (more than 5 items)? 3. What is the first step to commission a transmitter on service? 4. What is RTD? 5. Find the output value in MA of a temperature transmitter (RTD Type) at 120degree celius? 6. What is the O/P signal of a pneumatic transmitter? 7. What is the O/P signal of an elctronic transmitter? 8. What is the close loop and open loon?

4 Answers  

---

any questions on motor and energy conversions machines?

0 Answers   ABB,

---

In split range control, we will control 2 outputs with time interval. Eg :(with 4-20 ma signal, for 4-12 ma we are operating one control instrument like valve & for 12-20ma we are operating other control instrumet (other valve). If we get a signal of 15ma to first instrument (Valve 1), what will happened to the first valve, and if we get signal above 20 ma to 2 valve what will happened ?

3 Answers  

---

If boiler drum level transmitter is not working properly what you will do for resolving the problem in plant running condition?

2 Answers  

---