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.Management Sciences
Category: Process Control and Instrumentation
For a feed back control system to be stable, the _________________?
A. Roots of the characteristic equation should be real
B. Poles of the closed loop transfer function should lie in the left half of the complex plane
C. Bode plots of the corresponding open loop transfer function should monotonically decrease
D. Poles of the closed loop transfer function should lie in the right half of the complex plane
On-off controllers are normally used for________________?
A. Low loads
B. Temperature changes
C. Flow rate changes
D. None of these
Emf developed by a thermocouple while measuring a temperature of 400°C is 22 mV. The type of thermocouple used is ___________________?
A. Chromel-alumel
B. Iron-constantan
C. Platinum-rhodium
D. Platinum-platinum + rhodium
Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a __________________?
A. Thermocouple
B. Resistance thermometer
C. Mercury in glass thermometer
D. Vapor pressure thermometer
Liquid argon level in a pressurised storage tank (at 3 kg/cm2) is measured by a/an ____________________?
A. Gage glass
B. External float gage
C. Differential pressure gage
D. None of these
Which of the following is an undesirable dynamic characteristic of an instrument ?
A. Reproducibility
B. Dead zone
C. Time lag
D. Static error
Stroboscope is used for the measurement of _________________?
A. Rpm of a flywheel
B. Frequency of light
C. Depression of freezing point
D. Liquid level under pressure
Thermistor, which has high temperature co-efficient of resistivity, is used as the sensing element in resistance thermometer. It is a/an ?
A. Insulator
B. Conductor
C. Solid semi-conductor
D. Liquid semi-conductor
_______________ thermometer cannot measure sub-zero (< 0° C) temperature ?
A. Mercury in glass
B. Bimetallic
C. Vapor pressure
D. Resistance
Normal mercury thermometer can be used to measure a temperature of about 300°C. However, its maximum temperature measurement range can be increased upto about 500°C by__________________?
A. Filling nitrogen under pressure in the stem
B. Increasing the diameter of the tube
C. Using steel tube in place of glass tube
D. Accounting for the tube expansion
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