Electrical engineering labs modernization

The Need for Modernization of

Electrical &Electronics Engineering Laboratories

BY JABEZ WINSTON.C(11EE16)

3rd year EEE

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Areas where the laboratories should change…. Measuring Connecting Power supply Miscellaneous

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MeasuringWhy do engineering college labs use old MC and MI instruments? Why not

digital meters?

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My counter argument:First of all , you cannot be remain outdated.Second thing is you measure only voltage/current/power with those instruments and hence there is no scope of learning lot from them .Just for the sake of academic purpose , one or two experiments can be done using such instruments.We are in age where things are shrinking.Hence there is no point in having bulky instruments anymore.

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Disadvantages of Using Analog instruments:Less accuracyPoor resolutionCan be easily damaged if mishandledHigh costLarge sizeInternal impedance is low in case of voltmeter. For example , a (0-30V) MC voltmeter’s internal resistance is only 30kΩ which increases the chance of loading effect.

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Advantages of using digital instruments

Highly accurateHigh resolutionLow costAuto-ranging feature in some multimetersSmaller sizeHigh internal impedance(commonly 1MΩ,occasionally 10M Ω and sometimes even 40MΩ)

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Problems with analog instrumentsDemonstration of Loading Effect

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Problems continued…

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Autorange multimetersCapable of measuring frequency,capacitance,AC current,etc.,

Pocket size DMM

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Clamp meter capable of measuring current upto 1000 A

Manual ranging multimeter

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ConnectingThe way we connect measuring

equipments,auxillary equipments,device or machine should change.

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The problem of many instruments!!2 voltmeters,6 ammeters!!

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Typical Machines Lab Table

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Connection designA voltmeter( preferably digital) can be permanently connected across R and Y(Both supply and machine)R and N(Both supply and machine)A1 and A2(+) and (-)

A ammeter can be connected with (+),R,A1,F1 terminals

The obvious reason is that it is frequently required to measure armature voltage , field current , line voltage , phase voltage , supply voltage

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This would be better…

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Simplified circuit

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Advantage of this connection design

Time is savedMore complicated experiments can be carried outMonotonous connecting work is minimized and hence learning is enhanced

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Power supplyWhy not use 100V or 120V AC and 100V DC

for experimental purposes?

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Need for lower voltagesLower voltages are saferThe supply voltage in USA is 120V 60HzThe power supply is Japan is 100V(50Hz is Eastern Japan and 60Hz in Western Japan)If phase voltage is 115V,then line voltage is just 200V If supply voltages are lower,you can experiment more with less riskIf supply voltages are higher,the only less experimenting is possible

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Miscellaneous(My crazy ideas.Not to be taken seriously)

How about working with smaller motors and generators like thisRated voltage: 115VRated current:2.5 APower: ½ HP…..We could save the scarce power like this!!!Starting and stopping the motor would be easy.

How about using power electronic devices to control voltage, current instead of old 3 point starter , autotransformer , rotor resistance starter??? jω©2013

Thank you!!!

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