This preview shows page 1 - 3 out of 13 pages. View full document 1 SENSORS & TRANSDUCERS UNIT-1 : INTRODUCTION 1 FUNCTIONAL ELEMENTS OF AN INSTRUMENT Most of the measurement systems contain three main functional elements. A first order instrument has a time constant of 2 s. For sinusoidal input to the instrument, find. the frequency at which the amplitude of the output signal is 0.8 times the amplitude of the The symbol may be ac- companied by a tag number. 4.2 Functional identification 4.2.1 The functional identification of an instrument or its functional equivalent consists of letters from Table 1 and includes one first-letter (designating the measured or initiating variable) and one or more succeeding-letters (identifying the functions performed). In the next section an overview of instruments will be given. Further information can be obtained in the instruments and instrumentation section of this encyclopedia. 2.1. Instruments Instruments are devices that monitor and measure physical variables. The physical parameters under investigation are known as measurands. The primary elements of FUNCTIONAL ELEMENTS OF AN INSTRUMENT: Most of the measurement systems contain three main functional elements. They are: i) Primary sensing element . ii) Variable conversion element & iii) Data presentation element. Primary sensing element: The quantity under measurement makes its first contact with the primary sensing element of a measurement Draw the block diagram showing the basic functional elements of instrument and explain the functions of each. 2. Explain how an instrument is calibrated. 3. Explain on the static and dynamic characteristics of a measurement system. 4. Write briefly on instrument standards. 5. Explain in detail the different types of errors in measuring Instruments • It is desirable to describe both the operation and performance of measuring instruments and associated equipment in a generalized way without recourse to specific physical hardware. • Here we focus on the operation which can be described in terms of the functional elements of an instrument or instrument system. INSTRUMENTS A systematic organization and analysis are more important for measurement systems. The whole operation system can be described in terms of functional elements. The functional elements of generalized measurement system. Most of the measurement system consists of following functional elements. 1. Primary sensing element 2. 2 Instrument elements and mechanisms 6 3 Instrument displays, panels and layouts 19 4 Pitot-static instruments and systems 50 S Primary flight instruments (attitude indication) 116 and the many functional and constructional changes, cut as in the evolutionary processes of most technological fields, complexities arise more often than not in 11. Instrument Drift • It is defined as the variation of output for a given input caused due to change in sensitivity of the instrument due to certain interfering inputs like temperature changes, component instabilities, etc. • P rime so u c eso as hmi alt ng d changing mechanical stresses. • Dri f ti sa c om pl ex hnme rw ic b v d ec 1. Indicating Function: Different kinds of methods for supplying information concerning the variable quantity under measurement. 2 Recording Function: Stores or write the value of a quantity under measurement. 3. Controlling Function: In this case, the information is used by the inst