Topic:-Classification of Instrument (1) Baldha Sandip (001) (2) Bapodariya Namrata(002) (3)Borda Jaydeep(003) (4)Bhuvir Kuranal(004) (5)Barda Akash(005) Guided By:-Vinod sir

Classification of Instrument Absolute and Secondary Instrument, Analog and digital Instrument, Deflection and Null type instrument,

Absolute instrument:- These instrument read the quantity under measurement indirectly i.e. in terms deflection, degrees and meter constant. The actual value under measurement can be calculated by using the formula=deflection multiple by constant meter. Ex. of these instrument:- (1)Tangent galvanometer (2)Cureent balance meter

Secondary Instrument:- These instrument read the quantity under measurement directly i.e. the meter commonly used that as ammeter,voltmeter,watt meter and energy meter. Types:- (1)Depending upon the principle of operation, (2)Depending upon permissible percentage error, (3)Depending upon application,

Depending upon the principle of operation:- Depending on effect of electric current for producing the deflecting torque in the meter classified:- 1)Magnetic meter 2)Induction meter 3)Hot wire meter 4)Electrostatic meter Depending upon permissible percentage error:- types:-(a) standard meter, (b) Substandard meter, (c) First grade instrument, (d) Second grade instrument, Standard meter:-these are the most accurate meter which are used for calibration of meter, the permissible error in these meter is 0.2% and less than 0,2%.

Substandard meter:-the permissible error is of order of 0. 2% to0 Substandard meter:-the permissible error is of order of 0.2% to0.5% of full scale deflection. First grade instrument:-the percentage permissible error in these meter is the order of 1 %to 5% of the full scale deflection.thse meter are used for testing in lab. Second grade instrument:-there permissible error is 2% to3% and used the panel board.

Depending upon application:- types, (a) Indicating instrument. (b) Recording instrument, (c) Integrating instrument, Indicating instrument:-these instrument gives the intentions value of quantity under measurement, e.g. ammeter,voltmeter,wattmeter… Recording instrument:- these meter gives continues record of the quantity under measurement over a certain period of time. these meter a graphical representation of the quantity under measurement with the help of a pen and paper. e.g. recoding types of ammeter,voltmter used in generating station and distribution substation.

Integration Instrument:- these meter gives summation of the quantity under measurement 0ver a certain period of time. the reading is achieved with the help of counting or registering mechanism. the reading of these meter is in terms of digits for energy meter.

Null type Instrument:-

In the null type of instrument the method of comparison between the measurement and the standard result in to obtaining a null or zero indicating which determine the magnitude of the measured. A null condition or zero condition is sometimes depended upon various parameter of the measurement. E.g. a d.c potentiometer the galvanometer which is use as null detector will shown non zero reading if the sliding contact on find a potential drop&unkone vtg dropped

Deflection type instrument

In deflecting type of instrument the torque moves the pointer moving on a calibrated scale. magnitude of deflating torque directly proportional to the quantity under measurement. It produced by using various effect of electric current such as magnetic effect, heating effect, chemical effect etc. The another torque knows as controlling torque exactly opposite to deflecting torque whose magnitude is directly proportional to the deflection of pointer.

When quantity (voltage & current) is applied to the measuring instrument defalcating torque is produced When Tc = Td the pointer becomes stationary and shows the steady reading. Example of instrument is PMMC , Dynamometer , Moving iron etc.ammeter and voltmeter

Analog instrument The signal which continuously vary and take infinite values for a given range are called as analog signal. The instrument that involves the use of analog signal is called as an analog instrument. In analog system the function continually varies. E.g. deflection type instrument like PMMC ammeter,voltmeter,Null deflection instrument like DC potentiometer ,Whetstone meter bridge etc.

Digital Instrument:- The signal which vary in discrete steps and take a finite different values in the given range are called digital signal. The instrument that use of digital signal is called as digital instrument. E.g. of digital instrument are logic analyzer, Microprocessor based instrument, computer, Digital counter etc.

Thank you…….