What is the effect of power factor on wattmeter reading?

What is the effect of power factor on wattmeter reading?

If the PF < 1.0, the load is partially reactive. The current is not i phase with the voltage. The kVA will be greater than the kW. So for a given current (and given kVA), with a lower PF, the watts shown on a wattmeter will be lower.

Is power factor of the load affected the wattmeter readings justify?

If the PF is 1.0, the load is pure resistive. The current is in phase with the voltage, and there is no reactive component. So for a given current (and given kVA), with a lower PF, the watts shown on a wattmeter will be lower.

How does a wattmeter measure power?

A wattmeter does a complex job, measuring the power flowing through an electrical circuit. It simultaneously measures the voltage and current values and multiplies them to give power in watts. The three main types are electrodynamic, electronic and digital.

When power factor is 1 What does the two wattmeter reads?

If the power factor of the load is unity i.e., cos φ = 1. We get φ = 0°. The power measured by the wattmeter-1 is, W1 = VL IL cos(30 – 0) = √3/2 VL I.

What will be variation in wattmeter reading if the power factor of the load is zero?

Thus we see that, when power factor of load is 0.5 lagging then power is only measured by first wattmeter and reading of second wattmeter is ZERO. Case3: When power factor of load is zero. Thus we see that, when power factor of load is zero then one wattmeter reads +ive while second wattmeter reads –ive.

Does a wattmeter measure true power?

Digital. A modern digital wattmeter samples the voltage and current thousands of times a second. For each sample, the voltage is multiplied by the current at the same instant; the average over at least one cycle is the real power. The real power divided by the apparent volt-amperes (VA) is the power factor.

How does 2 wattmeter method measure power factor?

One wattmeter measures voltage between the R and T phases, a second wattmeter measures voltage between the S and T phases and a third wattmeter measures voltage between the R and S phases. The phase currents are measured by each wattmeter. The two-wattmeter method is still used to calculate total power. Pt = P1 + P2.

How does a wattmeter work from the power factor?

This kind of wattmeter does not directly work from the power factor. It averages the instantaneous voltage times current. The force on the needle is proportional to the voltage times the current, which is the instantaneous power. A spring causes the needle to deflect linearly with applied force.

How is the power factor of a circuit calculated?

Power factor = Wattmeter reading / (Voltmeter reading x ammeter reading). This method involves mathematical calculations. Sometimes it is required to measure the power factor of the circuit instantaneously when the power factor of the load is varying continuously.

What happens when one of the wattmeter reads zero Watts?

In the case where a wattmeter reads zero watts, because the meter reads real power, you know that the power in the system is purely reactive. Thus, the phase angle of the system must be 90 degrees. Taking the cosine of 90 yields a power factor of zero.

What is the working principle of a power factor meter?

The basic working principle of power factor meter is similar to that of dynamometer type wattmeter i.e. when the field produced by moving system tries to come in line with the field produced by the fixed coil, deflecting torque is exerted on the moving system which deflects the pointer attached to it (the moving system).