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INSTRUMENTATION

5TH

SEM BE ELECTRICAL ENGGGUNIT-1

Generalized Instrumentation System

PRESENTED BY:

Saurabh K Singh

Nagar Yuwak Shikshan SansthasRAJIV GANDHICOLLEGE OF ENGINEERING & RESEARCH

Department of Electrical Engineering

Academic Session: 2012-13

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CONTENTS:

Definition Active and Passive transducers

Digital and Analog mode of operation

Static and dynamic characteristic and performance

of instruments Statistical treatment of measurement errors

Error distribution

Probability tables

Combination of errors

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DEFINITIONOFINSTRUMENTATION

In order to guarantee the objectivity of a measurement,we must use artifacts (tools or instruments). The task ofthese instruments is to convert the state or phenomenoninto a different state or phenomenon that cannot bemisinterpreted by an observe. The field of designing

measurement instruments and systems is calledinstrumentation.

Instrumentation systems must guarantee the requireddescriptiveness, the selectivity, and the objectivity of the

measurement.

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ACTIVEAND PASSIVETRANSDUCERS: Problem:

What is a transducer and what are the differences between an active and

passive transducer?

Solution:A transducer is a device that converts input energy into output energy.Typically the output energy is differing in kind but related to the input.

Active transducers generate electric current or voltage directly in response to

environmental stimulation. Examples of active transducers are thermocouplesand piezoelectric accelerometers. Thermocouples produce a voltage relatedto a temperature of two metals and if the two junctions are at differenttemperatures, electricity is generated.

Passive transducers produce a change in some passive electrical quantity,such as capacitance, resistance, or inductance, as a result of stimulation.These usually require additional electrical energy for excitation. A simpleexample of a passive transducer is a device containing a length of wire and amoving contact touching the wire. The position of the contact determines theeffective length of the wire, varying the resistance of the length of wire. Otherexamples of passive transducers are strain gauges, resistance temperaturedetectors (RTDs), and thermistors.

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DIGITALAND ANALOGMODEOFOPERATION:

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STATICANDDYNAMICCHARACTERISTICANDPERFORMANCEOFINSTRUMENTS :

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STATISTICALTREATMENTOFMEASUREMENTERRORS :

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ERRORDISTRIBUTION:

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PROBABILITYTABLES:

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COMBINATIONOFERRORS :