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A wattmeter reads the true power of a load, regardless of its power factor.

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How do you calculate power factor if line voltage and line current are measured from motor terminal?

Power factor is the ratio of true versus apparent power. For example, a power factor of 1 means that one watt of measured power is one watt of real power, while a power factor of 0.5 means that one watt of measured power is two watts of real power.To measure power factor, measure voltage, current, and the phase angle of current related to voltage. Phase angle is between 0 and 360 degrees, 360 degrees being one line cycle.A power factor of 1 means that the phase angle is 0 degrees.A power factor of 0.707, assuming that voltage and current are measured on the same scale, means that the phase angle is 45 degrees. It would be +45 degrees for a capacitive load and -45 degrees for an inductive load. You can use trigonometry, sines and cosines, to figure this out, or you can use the pythagorean theorem to figure this out - its just a right triangle where the angle is the phase angle.By the way, a power factor of -1 means the load is actually a generator, and a power factor of 0 means the load is a pure capacitive or inductive load with a phase angle of +90 or -90 degrees.Power factor is a concern because watt-meters measure apparent power. If the power factor is too low, it will seem that the energy used to lower than reality. The problem is, even in the worst case of + or - 90 degrees, energy is still required to move the current back and forth in the circuit, and that energy must come from the power supply. That's why we talk volts-amps (VA), volts-amps-reactive (VAR), and watts (W) in AC circuits, and none of them are the same thing.


Why ac motor has low power factor?

because of high resistance in the load.


Why a rotor of an alternator at rated power dissipates more heat at a low power factor load than at a high power factor load?

at lower power factor current drawn by load is high and at higher pf the current drawn is less...


What are the adverse effects of poor power factor?

Low power factor means higher than necessary load currents. These require unnecessary expenditure on the amount of copper in supply equipment such as cables, transformers, and switchgear. Higher than necessary load currents also mean greater voltage drops and poorer voltage regulation.


How does low power factor effects conductor size?

A load with a low power factor draws more load current than necessary, so the supply conductors need to have a greater cross-sectional area than would otherwise be necessary.

Related Questions

What is your opinion whether a low power factor can damage 20 watt led lights installed in a hotel?

The load (in this case, your led lighting) determines its own power factor. While you can improve the power factor (move it towards unity) at the terminals, you are not actually changing the power factor of the load.


When you applied 230 volt and current of choke is .43 amp then according to power formula the value is 99.82 watt while on tube light it is marked as 40 watt how it can be possible?

In an AC system the power is often less than the volts times the amps. The full formula is watts = volts times amps times power-factor. Some bulbs have a power-factor as low as 0.5.


Why you use low power factor wattmeter on primary and unity power factor on secondary side of transformer?

There is no such thing as a 'low power-factor' wattmeter. A wattmeter always reads true power, regardless of the load's power factor.


Can a laptop with a 65 watt power adapter be powered up with a 300 watt dc to ac inverter with 140 watt continuous operation with low voltage and overload protection?

Yes, theoretically you can power up a laptop with a 65 watt power adapter using a 300 watt DC to AC inverter, as the laptop will only draw the power it needs (65 watts). However, it's important to ensure that the inverter has low voltage and overload protection to prevent any damage to the laptop or the inverter itself during operation.


Does low load in transformer lead to low power factor?

Power factor is determined by the nature (resistive, inductive, capacitive) of a load, not whether it is a low load or a high load.


Why transformer power factor taken unity?

It isn't! A transformer operating at no load has a very low power factor.


What mean power factor 0.26 lead?

When looking at power factor, it is the ratio of watts (true power) to VA. The power factor is how we measure power systems. A person with a low power factor like .26 will have a higher electricity bill.


What is the maximum distance reached using IR transmission?

Between 2 standard IR devices it is 1 meter. Between 2 low power IR devices it is 0.3 meter Between a standard and a low power IR device it is 0.2 meter


How do you decide the pachage size of resistor with same value of resistance?

The package size roughly equates to wattage- the amount of power a resistor can safety dissipate without damage. Use your basic ohms law to figure out how much power will be dissipated by the resistor, and use the next largest size. A good safety factor is 2, so if you calculate the power is 1/4 watt, use a 1/2 watt resistor. One other factor is duty cycle. A component with a low duty cycle would need less of a safety factor, or perhaps could be sized according to the AVERAGE power in the resistor.


Can you run a 500 watt amplifier at low volume on a 140 watt ac converter?

Yes, you can run a 500 watt amplifier at low volume on a 140 watt AC converter. The power consumption of the amplifier will depend on the volume level it is set to. As long as the amplifier is not drawing more power than what the converter can supply, you should be able to use them together safely. Keep an eye on the power indicator on the converter to ensure it's not being overloaded.


What is the main reason for Low Power Factor?

inductive/lagging load


How do you calculate power factor if line voltage and line current are measured from motor terminal?

Power factor is the ratio of true versus apparent power. For example, a power factor of 1 means that one watt of measured power is one watt of real power, while a power factor of 0.5 means that one watt of measured power is two watts of real power.To measure power factor, measure voltage, current, and the phase angle of current related to voltage. Phase angle is between 0 and 360 degrees, 360 degrees being one line cycle.A power factor of 1 means that the phase angle is 0 degrees.A power factor of 0.707, assuming that voltage and current are measured on the same scale, means that the phase angle is 45 degrees. It would be +45 degrees for a capacitive load and -45 degrees for an inductive load. You can use trigonometry, sines and cosines, to figure this out, or you can use the pythagorean theorem to figure this out - its just a right triangle where the angle is the phase angle.By the way, a power factor of -1 means the load is actually a generator, and a power factor of 0 means the load is a pure capacitive or inductive load with a phase angle of +90 or -90 degrees.Power factor is a concern because watt-meters measure apparent power. If the power factor is too low, it will seem that the energy used to lower than reality. The problem is, even in the worst case of + or - 90 degrees, energy is still required to move the current back and forth in the circuit, and that energy must come from the power supply. That's why we talk volts-amps (VA), volts-amps-reactive (VAR), and watts (W) in AC circuits, and none of them are the same thing.