Principle And Types Of Analog And Digital Voltmeters
Ø Basically an electrical indicating instrument is divided into two types. They are
i) Analog instruments
ii) Digital Instruments.
Ø Analog instruments are nothing but its output is the deflection of pointer, which is proportional to its input.
Ø Digital Instruments are its output is in decimal form.
Ø Analog ammeters and voltmeters are classed together as there are no fundamental differences in their operating principles.
Ø 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.
Ø In an ammeter this torque is produced by a current to be measured or by a definite fraction of it.
Ø In a voltmeter this torque is produced by a current which is proportional to the voltage to be measured.
Ø 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.
