Principle And Types Of Analog And Digital Voltmeters

 Basically an electrical indicating instrument is divided into two types. They are

i) Analog instruments

ii)      Digital Instruments.

·         Analog instruments are nothing but its output is the deflection of pointer, which is proportional to its input.

·         Digital Instruments are its output is in decimal form.

·         Analog ammeters and voltmeters are classed together as there are no fundamental differences in their operating principles.

·         The action of all ammeters and voltmeters, with the exception of electrostatic type of instruments, depends upon a deflecting torque produced by an electric current.

·         In an ammeter this torque is produced by a current to be measured or by a definite fraction of it.

·         In a voltmeter this torque is produced by a current which is proportional to the voltage to be measured.

·         Thus all analog voltmeters and ammeters are essentially current measuring devices.

The essential requirements of a measuring instrument are

 (i)      That its introduction into the circuit, where measurements are to be made, does not alter the circuit conditions ;

 (ii)   The power consumed by them for their operation is small.