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High CMRR Instrumentation Amplifier (Schematic and Layout) design for biomedical applications

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Instrumentation amplifiers are intended to be used whenever acquisition of a useful signal is difficult. IA’s must have extremely high input impedances because source impedances may be high and/or unbalanced. bias and offset currents are low and relatively stable so that the source impedance need not be constant. Balanced differential inputs are provided so that the signal source may be referenced to any reasonable level independent of the IA output load reference. Common mode rejection, a measure of input balance, is very high so that noise pickup and ground drops, characteristic of remote sensor applications, are minimized.Care is taken to provide high, well characterized stability of critical parameters under varying conditions, such as changing temperatures and supply voltages. Finally, all components that are critical to the performance of the IA are internal to the device. The precision of an IA is provided at the expense of flexibility. By committing to the one specific task of
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Measurement of the 3phase power by the two watt meter method.

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Aim:- Measurement of the 3phase power by the two watt meter method.
Apparatus:-
Ammeter (0-5A)- 1no.
Voltmeter (0-600v) –1no
Rheostat (100-5A)-1no
Resister -100K-3nos.
Circuit Diagram-
Theory:-
Here two wattmeter are connected to measure power in 3 phase circuit. Let V1,V2,V3
be rms values of phase voltage and i1,i2,i3 be rms values of line current
Phase voltage=V1=V2=V3=V
Line voltage=V13=V23=V12=Ö3V
Power factor=cos f
Reading of P1 wattmeter =V1Ö3i1cos(30-f)
= Ö3Vphiphcos(30-f)
Reading of P2 wattmeter= V2Ö3i2cos(30+f)
= Ö3Vphiphcos(30+f)
Sum of two wattmeter readings=P=P1+P2
= Ö3Vphiph[cos( 30-f)+cos(30+f)]
=3Vicosf
Observation Table:-
Sr no Voltage Current Power 3 phase watt
Procedure:-
1) Make the arrangement as per the circuit diagram.
2) Adjust supply voltage to 100v take the reading when the wattmeter is connected
between the R and Y phase.
3) Repeat previous for the different reading of the voltage.
4) Also note the corresponding current.
5) Now connect wattmeter between R and B phase .
6) Repeat the previous procedure which will give by the total power consumed by
the load.
Result:- Hence it is found that the calculated power and the measured power by the two
wattmeter method.
Viva Questions:-
1)What do you mean by the 3phase wattmeter?
2)Explain the short how the wattmeter is connected in the circuit to measure
the power delivered to the Load?

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