Question

- illalhich type of analoque instrument operates I on the motor principle ? What is the different between this analoque instrument and motor related to application ? 1 i) Illustrate the principle of operation of this andloque intrument with diagram.

Answer 1

i Pormancnt Magnet Moving Coil instrument oportes on the motor principle ad In a motor, the rotation is unlimited, ie it has - to run at very high rpm like 1000rpm, 1500 rpmete and it has to bear the mechanical load, whereas in pm me instrument (analogue instrument) notation is limited , whenever corrent passes through coil, the pointer will move only upto a certain point mation of PMMC meten Principle of Operation 4 pm - meter f Pirot and jewelled bearing - spring - Aluminium frame. 9 whenever corrent passes through coil, as magnetic field is present already, By Lorentas principle current carrying conductor placed in magnetic field experiences ; 6% face , hence painter starts moving from zeroposition so This face is known as deffecting Tanque (Td) to stop the pointer at requined value, control Sgannel arquero dizer needed, it is provided by spring (TC)

[ Hightening process Foxe f = BIL sink Bis magnetic field, I is current, Light of conductor , & is angle between B&I here x=90° , f = BIL for Ntwins F = NBIL - Td = fxd ENBILD =NBAI Td a I Nis no of twins of copper coil , Ais area of Copper under steady stade To It Tc = Td Te = k co kco. =NBAI. 0 = NBA I kc a ois deflection of pointen , keis spring constant csscanned with CamScanner