Question { Adhunik, 7728 }

in transmiters(rose mount) how to check output 4-20ma ? and
input 24v? i need exact explanation?

Answer

In rosemount transmitter, open the back side cover which
contains termination.
To check input Power:
switch on the multimeter and select the DC voltage
measurement and connect the positive(red) lead to positive(+
indication in the transmitter) and negative (Black) lead in
the negative terminal(-). then the reading shows 24V DC.

To Check 4-20ma output:

Switch on the multimeter and change the red lead to MA
section and remove one wire from the transmitter and connect
as series. it will show how much reading.

Question { DEWA, 11603 }

What are the automatic controller MODES?

Answer

In automatic controller there are two modes available to control the process. One is called Automatic mode, it will control the process automatically by comparing the feedback input with the set point. The another method called Manual mode, in this mode the operater check the measured input from the field and give the command manually for the final control element.

Question { ABB, 13945 }

what is coriolis principle for mass flowmeter?

Answer

If there is no flow then no coriolis effect, if there is a flow then it will make coriolis effect. In coriolis flow meter, consists of two parellel flow tubes connected with a drive coil and two magnetic pick ups on either side of the tubes. During no flow condition, the drive coil makes a small vibratio in the tubes one another. Due to this vibration the magnetic pickoff coil will generate a voltage equilant to a sine wave. In this condition sine wave created by both the inlet and outlet magnetic pick up is same.
During in flow condition, then there is a twisting in the flow tube. In the inlet side the flow opposes the vibration and in the outlet side the flow adds the vibration and makes twistinh in the flow tube. Due to this twisting the pickoff coil makes different sine wave output. By measuring the phase shift with reference time will be calculated as t in micro seconds. Multiply t with the calibration factor, we will get the mass flow in grams/sec.

Question { 4502 }

with the help of suitable diagrams different types of control
valves

Answer

Double acting
Single acting
Fail to Open
Fail to Close

Question { 5673 }

how to measure flow with dp

Answer

By using orifice plate we can measure the differential pressure between the upstream and downstream. This diffferential pressure is proportional to the sqaure of the flow.ie Q2 = DP
(or) Q= sq. root of DP. So by using square root extractor we can get the volumetric flow.

Question { Petrofac, 7262 }

what is Dry Leg calibration and where is it used

Answer

Dry leg calibration is nothing but the calibration of a DP tx in an closed tank.In a closed tank , the LP side is connected with the top of the tank and HP side is connected with the bottom of the tank to measure the height of the liquid column present in the tank.

Phigh = Pgas + S.H
Plow = Pgas
DP = Phigh - Plow = S>H

Question { Alkyl Amines, 10105 }

How to connect PLC to DCS ?

Answer

In DCS system , their is an option called third party interface.this third party interface is mostly in serial communication method. so by using the third party interface card, we can connect the PLC using serial communication method.

Question { 5445 }

Explain the thermocouple and RTD?

Answer

RTD: Resistance Temperature Detector,
Principle: Every metal has its own different characteristics. wen a metal undergoes heat then its electrical or mechanical characteristics will change proportionally.
In case of RTD, wen it undergoes heat then its electrical characteristcs will change proportionally.By measuring the resistance,we can find out actual temperature.

Thermocouple: thermocouple is working on the principle of Seeback effect. two dissimillar metals are combined together and forms two junctions(Hot and Cold). wen applying a heat on the one junction there is an output as milli volt. by measuring the milli volt, we can calculate the temperature with known reference temperature(cold Junction).

Question { 5534 }

GIVE BRIEF DESCRIPTION ABOUT "DCS"

Answer

DCS is nothing but, Distributed control system. Nowadays most of the manufacturing or production plants are running with dcs.There is a central controller located in a system panel and the cotrol activities are distributed to each and every controller depend up on the process.
Due to the distribution of control, we can control the process efficiently.
Also we can connect third party interfaces like PLC and SCADA through serial communication links.
The DCS is introduced in mid 1970's by Honeywell and Yokagawa.