Hello Mr. Biswajit Gupta,

AH Meter = Amp Hour Meter

Years ago I was dragged kicking and screaming into an industrial system which needed three variables to be measured. AC Current (~150 Amps), AC voltage (480 VAC) and Temperature (135-150 Degrees F). You can see a visual example at the following address.
http://members.aol.com/temperatu...xample.gif

There was another problem which was no power cables could be removed or power could not be turned off to hook up the measure devices. Needless to say this killed that project and after a year of tinkering I came up with a solution.

I modified three analog AC clamp on amp meters and one analog AC voltmeter meter so that their meter movement could be converted into a 0-5 VDC signal.

This was done using a simple differential opamp circuit to convert the meter movement voltage (0-50 Mill-Volts) and a 100 gain opamp amplifier to convert 50 Milli Volts into 5 volts (0.050VDC X 100 = 5.0VDC)

The 0-5VDC signal was connected to an analog to digital converter (ADC) which was hooked up to a 89C2051 integrated circuit.

Once the digital equivalent of the current and voltage was known it was a simple matter to calculate Kilowatt power (what the power company charges you for) using the formula Kilowatt Power = Current X Voltage X 1000.

The entire project was later used on many jobs which had to have power calculated without distributing any power cables or turning off any power.

Good luck,

Charles Bannister