Indicators & Recorders

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INDICATORS & RECORDERS


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Agenda

1. INDICATORS

2. RECORDERS


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PRINCIPLE OF OPERATIONOPERATES ON THE BASIC PRINCIPLE OF INTERACTION OF MAGNETICFIELDS OF THE PERMANENT MAGNET AND THE CURRENT CARRYINGCONDUCTOR.

.

A movable coil in a magnetic field (no current). A movable coil in a magnetic field (current).

INDICATORS


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INDICATORS

THE COIL OF WIRE IS WOUND ON ANALUMINUM FRAME, OR BOBBIN, ANDTHE BOBBIN IS SUPPORTED BYJEWELED BEARINGS WHICH ALLOW ITTO MOVE FREELY.

HAIRSPRINGS ATTACHED TO EACHEND OF THE COIL ENABLE THE COIL TORETURN TO ITS INITIAL POSITIONWHEN THERE IS NO CURRENTIT ALSO RESISTS MOVEMENT OF THECOIL WHEN THERE IS CURRENT

THROUGH THE COIL WHEN THEATTRACTION BETWEEN THE MAGNETICFIELDS (FROM THE PERMANENTMAGNET AND THE COIL) IS EXACTLYEQUAL TO THE FORCE OF THEHAIRSPRINGS, THE COIL WILL STOP

MOVING TOWARD THE MAGNET


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PERMANENT MAGNET MOVING COIL INDICATOR

INDICATORS


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RECORDERS

TO RECORD AND PRESERVE MEASUREMENT OFPROCESS VARIABLES TIME WISE.

PROCESS PARAMETER BEHAVIOUR CAN BE SEENINSTANTLY/STUDIED LATER ON WHENEVERREQUIRED.

DEPENDING ON THE KIND OF RECORDINGTECHNIQUES RECORDERS MAY EITHER BEANALOG OR DIGITAL.

ANALOG RECORDERS ARE FURTHER CLASSIFIEDINTO GRAPHICAL RECORDERS, OSCILLOGRAPHICRECORDERS AND MAGNETIC TAPE RECORDERS.

ANALOG RECORDERS MAY ALSO BE SINGLE POINTOR MULTIPOINT RECORDERS.


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RECORDERSGRAPHICAL RECORDERS =STRIP CHART RECORDERS

A chart recorder is an electromechanical device that records anelectrical or mechanical input trend onto a piece of paper (the chart).

Chart recorders may record several inputs using different color pensand may record onto strip charts or circular charts.

Chart recorders may be entirely mechanical with clockworkmechanisms or electro-mechanical with an electrical clockworkmechanism for driving the chart (with mechanical or pressure inputs) orentirely electronic with no mechanical components at all (a virtual chartrecorder).

They are built in three primary formats.1) Strip chart recorders have a long strip of paper that is ejectedout the side of the recorder2) Circular chart recorders have a rotating disc of paper3) Roll chart recorders are similar to strip chart recorders except

that the recorded data is stored on a round roll, and the unit is usuallyfully enclosed.


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CHART RECORDER TYPES

STRIP RECORDER CIRCULAR CHART RECORDER

RECORDERS
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PRINCIPLE OF OPERATION

RHEOSTAT BATTERY

CHOPPER

AMPLIFIER

BI DIRECTIONALMOTOR

MECHANICAL LINKAGE

SELF BALANCING WHEATSTONE BRIDGE

RECORDERS


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GRAPHICAL RECORDERS: X-Y RECORDERS-While strip chart recorders record variables w.r.t time X-Y recorders gives a graphic record of the relationshipbetween two variables.

-This is done by having one self balancing potentiometercontrol the position of pen while the other controls theposition of the rolls.

-In another variation while the paper remains constant

one potentiometer moves the pen in X direction while theother in Y direction.

RECORDERS


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OSCILLOGRAPHIC RECORDERS:--The recorder consists of a number of galvanometer

elements mounted in a single magnet block.

-When current passes through galvanometer coils it

deflects under the influence of the magnetic field of thepermanent magnet.

-The U.V. light falling on the mirror attached to the coils isdeflected and projected on the u.v. light sensitive paper.

- The paper is driven past the moving light source andthus a trace of variation of current w.r.t is obtained.

RECORDERS


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MAGNETIC TAPE RECORDERS:--This device contains a recording head which reproduces

the electrical signal as a magnetic pattern on the amagnetisable medium known as the magnetic tape.

-The main advantage of magnetic tape recorders is thatthe recorded data can be reproduced.

RECORDERS


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PAPERLESS RECORDERSAccepts a variety of electrical i/ps viz. mA DC ,

V DC, mV, rtd i/p , pulse i/p, binary signals etc.

Provision for visible as well as audible alarms.

Options for digital, trend(horizontal/vertical/circular) as well as bargraphs(horizontal/vertical) displays are available.

Options for alarm summary, message summary,

memory summary available.Provision for both internal and external data

storage..

Can be incorporated in the existing LAN.


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PAPERLESS RECORDERS contd.


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INDICATORS AND RECORDERS

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Indicators & Recorders