JAN-2016
1. What is meant by measurement?
Measurement is an act or the result of comparison between the quantity and a
Pre-defined standard.
2. Mention the basic requirements of measurement.
· The standard used for comparison purpose must be accurately defined and should
be commonly accepted.
· The apparatus used and the method adopted must be provable.
3. What are the 2 methods for measurement?
· Direct method and
· Indirect method.
4. Explain the function of measurement system.
The measurement system consists of a transducer element which
converts the
quantity to be measured in an analogous form. The analogous signal is then processed by
some intermediate means and is then fed to the end device which presents the results of
the measurement.
5. Define Instrument.
Instrument is defined as a device for determining the value or magnitude of a
quantity or variable.
6. List the types of instruments.
· The 3 types of instruments are
· Mechanical Instruments
· Electrical Instruments and
· Electronic Instruments.
7. Classify instruments based on their functions.
Indicating instruments
Integrating instruments
Recording instruments
.
8. Give the applications of measurement systems.
· The instruments and measurement systems are sued for
· Monitoring of processes and operations.
· Control of processes and operations.
· Experimental engineering analysis.
9. Why calibration of instrument is important?
The calibration of all instruments is important since it affords the opportunity to
check the instrument against a known standard and subsequently to errors in accuracy.
· A primary standard
· A secondary standard with a higher accuracy than the instrument to be calibrated or
An instrument of known accuracy.
11. Define Calibration.
It is the process by which comparing the instrument with a standard to correct
the accuracy.
12. Name the different essential torques in indicating instruments.
Deflecting torque
Controlling torque
Damping torque
13. Name the types of instruments used for making voltmeter and ammeter.
PMMC type
Moving iron type
Dynamometer type
Hot wire type
Electrostatic type
Induction type.
14. State the advantages of PMMC instruments
Uniform scale.
No hysteresis loss
Very accurate
High efficiency.
15. State the disadvantages of PMMC instruments
Cannot be used for ac m/s
Some errors are caused by temperature variations.
16. State the applications of PMMC instruments
m/s of dc voltage and current
used in dc galvanometer.
17. How the range of instrument can be extended in PMMC instruments.
In ammeter by connecting a shunt resister
In voltmeter by connecting a series resister.
18. State the advantages of Dynamo-meter type instruments
Can be used for both dc and ac m/s.
Free from hysteresis and eddy current errors.
19. State the advantages of Moving iron type instruments
Less expensive
Can be used for both dc and ac
Reasonably accurate.
20. State the advantages of Hot wire type instruments
Can be used for both dc and ac
Unaffected by stray magnetic fields
Readings are independent of frequency and waveform.
TIPS OF THE MONTH
09.03.15 - 10.04.15
The PMG (Permanent Magnet Generator) is the only input Excitation to Automatic Voltage Regulator.
09.02.15 - 08.03.15
In cement industries, the rotary kiln temperatures are being monitored by wireless transmitters , which gives good results by freeing from the sensor cabling in hot zones.
10.01.15-09.02.15
Controlling a DCS logical or operational process from main server to a remote host located few thousand kilometer away is possible and known as remote patch access.
10.12.14 - 09.01.15
Radio Frequency type level transmitter can measure better level in a fast filling bulk material hopper/tank irrespective of the velocity of falling bulk material.
16.11.14 - 01.12.14
Control valves are also know as final controlling element.
TIPS OF THE WEEK
09.11.14 - 15.11.14
If you do select square root extraction in transmitter side for a non-linear flow then you must select linear in your DCS logic system.
03.11.14-09.11.14
While Erecting the orifice above the pipe line add the head pressure correction(P=hpg) to get the nominal flow.
26.10.14-02.11.14
The minimum distance for a digital control cable and analog control cable on two separate tray kept one above another, should be 50 mm, to block interference irrespective of its shielding.
18.10.14-25.10.14
Do you know each and every process of instrumentation system are categorized as zero , first and second order system.
11.10.14-17.10.14
In case of radio frequency type level detection , in non contact medium , its frequency gets effected by high voltages sources (nearby welding etc)
04.10.14-10.10.14
The communication of various smart sensors , controller , field instruments are known as ground bound telemetry.
25.09.14-03.10.14
While measuring vol flow by portable ultrasonic sensor , the sensor position must be exactly or nearer to advice sensor position shown by the controller after putting pipe -outer dia,thickness ,type of material and vel of sound in water in controller input parameter block.
18.09.14-24.09.14
Pressure gauge cum switch can be used as a tripping medium for critical equipment.
10.09.14-17.09.14
For installation of eccentric type orifice plate in gas pipe line , the bore hole always lies in bottom position.
03.09.14 - 09.09.14
In an open tank/drum, the gap between the tank/drum base & insertion pipe inside the tank should be minimum 100mm,which connects the higher side of the transmitter for tapping.
27.08.14 - 02.08.14
Instrument airline tapping for various network of critical pneumatic operated unit shall be taken from upper side from main air bus line.This will not allow the moisture(if any) in airline to carry-over to the concerned equipment.
