09-05-2012, 01:46 PM
ELECTRICAL AND ELECTRONIC MEASUREMENT WITH TRANSDUCERS
[attachment=21675]
MEASUREMENTS:
• Measurements means determination of anything that exists in some amount.
• Measurement of any quantity is essential in order to control it. For ex, one must be able to measure a variable such as ‘temperature’ or ‘flow’ in order to control it.
• The accuracy of control is dependent on the accuracy of measurement & hence good knowledge of measurement is essential for design of control systems.
• Definition of measurement:
• Measurement is defined as the process of obtaining a quantitative comparison between a predefined standard & an unknown magnitude.
• Requirements of a Measurement system:
(1) The standard used for comparison must be accurately known and commonly accepted.
Significance of Measurement system:
Measurement provides the fundamental basis for research & development as it involves measurement of various quantities pertaining to operation & performance of the device being developed.
Measurement is also a fundamental element of any control process, which requires the measured discrepancy between the actual & desired performances.
To ensure proper performance in operations of modern power stations to monitor temperature, pressure, vibrational amplitudes etc.
To establish the cost of products on the basis of amount of material, power, time & labour, etc.
Fundamental methods of Measurement:
(a) Direct comparison with primary or secondary standard.
(b) Indirect comparison through the use of calibrated system.
Direct comparison
In this method, measurement is made directly by comparing the unknown magnitude with a standard & the result is expressed by a number.
For ex, length measurement using a meter scale.
Here, the comparison is made with human senses which vary from person to person & hence highly undependable.
[attachment=21675]
MEASUREMENTS:
• Measurements means determination of anything that exists in some amount.
• Measurement of any quantity is essential in order to control it. For ex, one must be able to measure a variable such as ‘temperature’ or ‘flow’ in order to control it.
• The accuracy of control is dependent on the accuracy of measurement & hence good knowledge of measurement is essential for design of control systems.
• Definition of measurement:
• Measurement is defined as the process of obtaining a quantitative comparison between a predefined standard & an unknown magnitude.
• Requirements of a Measurement system:
(1) The standard used for comparison must be accurately known and commonly accepted.
Significance of Measurement system:
Measurement provides the fundamental basis for research & development as it involves measurement of various quantities pertaining to operation & performance of the device being developed.
Measurement is also a fundamental element of any control process, which requires the measured discrepancy between the actual & desired performances.
To ensure proper performance in operations of modern power stations to monitor temperature, pressure, vibrational amplitudes etc.
To establish the cost of products on the basis of amount of material, power, time & labour, etc.
Fundamental methods of Measurement:
(a) Direct comparison with primary or secondary standard.
(b) Indirect comparison through the use of calibrated system.
Direct comparison
In this method, measurement is made directly by comparing the unknown magnitude with a standard & the result is expressed by a number.
For ex, length measurement using a meter scale.
Here, the comparison is made with human senses which vary from person to person & hence highly undependable.