Question about Watt meter reading

[neoaspilet11]

wattmeter reading

Hello Guys,

From the Definition of AC power

P = VIcos (theta)

where theta is the phase angle between the voltage and Current,

If this phase angle is 90degrees or 270 degrees, will the meter reading be zero?

because cos(90) = 0

Thanks,
jack

 

[ptmsl]

Re: Watt meter Reading

Yes the power that is measured by the wattmeter of our houses does not measure the reactive component of the power consumed so if the load is purely reactive (capacitive or inductive) it will not be measured. In industrial applications however there is a penalty for reactive currents and we use power factor correction devices.

 

[bjeservice]

Watt meter Reading

yes the watt-hour reading is zero becuase for reactive loads there is no power dissipated ,as the power absorbed for one half cycle reloaded for the other half cycle.