A.C power consumption by circuit

[nitin.maurya1]

how to calculate total power consumed by a circuit driven by an A.C source?

 

[Raza]

The easier way is put a clamp meter on the main line (Phase) and measure the current consumption when you want to know of the time consumption. The after Ohm's Law multiply this reading with the supply voltage, you wattage (consumption of that time) will be available. Or you see the power consumption labels of all the equipment which you want to use at the same time and sum up.
Any further query, if needed, welcomed.

 

[nitin.maurya1]

this means we have to take account of phase difference between current and voltage for A.C power measurment?

 

[chuckey]

Yes, the real power (heating effect) is measured power V X A X Cos phi, where phi is the angle between the voltage and the current. The angle on resistive loads = 0 degrees, Cos phi = 1 therefore real power is V X A. On purely capacitive or inductive loads, phi is 90 degrees, Cos phi = 0, therefore real power = V X A X 0 = 0 !!!!
Frank

 

[KerimF]

Hi,

Calculating it is rather easy if we know the voltage and current waves; amplitude versus time. We just calculate the integral of v(t)*i(t)*dt during one cycle then divide the result by the cycle time.

Measuring it is not as simple. One method is to use an analogue multiplier IC after scaling the voltage and current properly, or by searching for an IC made for this job , unless one likes building a digital meter using an MCU with ADC.

Kerim