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# When current and voltage are 90 degrees out of phase what is the power?

Updated: 10/25/2022

Wiki User

14y ago

Power in an electric, AC circuit is the product of Volts, Amps, and the Cosine of the angle that separates them. When the Amps lag behind the Volts by 60 degrees, the product of Volts, Amps, and the Cosine of the angle between them provides half the power that would otherwise be available without the 60 degree angle. At 60 degrees, the cosine is 0.5 and at 90 degrees it is zero. So the product of Volts and Amps whenever they are 90 degrees out of phase will result in zero power.

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Q: When current and voltage are 90 degrees out of phase what is the power?
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### What is the power factor of an resititive load?

Power factor is the cosine of the phase angle between voltage and current. In a resistive load, current is in phase, i.e. with a phase angle of 0 degrees, with respect to voltage. Cosine (0) is 1.

### Phase difference between voltage and current at resonance?

The power factor is a measure of the phase difference. If they are exactly in phase the PF = 1. If they are 180 degrees out of phase PF = 0.

### What is the definition of reactive power?

For Single Phase, P = VI cos (theta) therefore cos(theta) = P/VI here P = Power V = voltage I = current theta = phase angle current to voltage cos(theta) = power factor For Three Phase, P = 3VI cos(theta) where V = phase voltage and I = phase current and theta = phase angle

### What is the active power consumed by pure capacitive reactance?

There is no 'active' power in a purely capacitive load. Active power is the result of the supply voltage multiplied by the in-phase component of the load current. In a purely capacitive load, the load current leads the supply voltage by 90 degrees and, so, there is no in-phase component and, hence, no active power.

### What is meant by in phase and out of phase?

Phase is a term that applies to alternating current or AC. The voltage of the supply goes through a cycle where it increases from zero to a peak value, then runs back to zero and out to a negative peak value, and then back to zero. It does that 50 or 60 times (cycles) each second. When a load is connected, current flows and the current also goes through the cycle of variations, exactly the same number each second. If the current keeps exactly in step with the voltage that is good and the voltage and current are 'in phase', but if the current is out of step it is 'out of phase'. The problem with out-of-phase currents is that there is a short period in each cycle when power flows the wrong way, back into the supply, so the overall power for a given amount of current is less than it should be. Instead of the power being voltage times current, it is voltage times current times a power factor that is less than 1. The power factor is the cosine of the phase difference between the voltage and the current. If the current is 90 degrees (one quarter of a cycle) out of phase, as it would be if the load was a capacitor, the power factor is cos 90 degrees, or zero, so no power flows even though current flows. But that current still produces power loss in the supply wiring, so the electric companies dislike loads with a poor power factor because they have no revenue for that lost power.

Related questions

### What is the power factor of an resititive load?

Power factor is the cosine of the phase angle between voltage and current. In a resistive load, current is in phase, i.e. with a phase angle of 0 degrees, with respect to voltage. Cosine (0) is 1.

### Phase difference between voltage and current at resonance?

The power factor is a measure of the phase difference. If they are exactly in phase the PF = 1. If they are 180 degrees out of phase PF = 0.

### Why do you use a phase advancer to improve the power factor?

Power Factor measures how much the current and voltage waveforms are out of phase. You get most efficient power transfer when the sine waves for voltage and current exactly match. When you multiply peak voltage and current you get the largest power. Depending on the phase relationships, you can bring the voltage and current waveforms into phase when you retard one or advance one against the other. Power Factor ranges from zero when the waveforms are 180 degrees out of phase to one when they are exactly in phase.

### How power is flowing when voltage and phase angle is maintained same?

Assume you are saying that the current and voltage are in phase and you want to know how power is affected. When Voltage and Current are in phase the Power Factor is 1 and you have maximum power being applied. When Voltage and Current are not in phase, Power Factor decreases from 1 toward zero.

### What is the definition of reactive power?

For Single Phase, P = VI cos (theta) therefore cos(theta) = P/VI here P = Power V = voltage I = current theta = phase angle current to voltage cos(theta) = power factor For Three Phase, P = 3VI cos(theta) where V = phase voltage and I = phase current and theta = phase angle

### What is the active power consumed by pure capacitive reactance?

There is no 'active' power in a purely capacitive load. Active power is the result of the supply voltage multiplied by the in-phase component of the load current. In a purely capacitive load, the load current leads the supply voltage by 90 degrees and, so, there is no in-phase component and, hence, no active power.

### Compare the phase relationship between the voltage and current in a purely resistive circuit and an RL circuit?

In a pure resistive circuit the voltage and current are in phase. In an inductive circuit they are fro zero to 180 degrees out of phase. If they are in phase the Power Factor is 1 and 180 degrees the PF is zero. The exact amount of the phase difference depends on the specific circuit.

### What is difference between 0.8 leading and 0.8 lagging power factors?

Power factor measures the phase difference between voltage and current. If they are in phase the Power Factor is one. If the current and voltage are out of phase the power factor is between zero and one. You can describe the PF by saying the current lags the voltage with a PF = .8 or the voltage leads the current with a .8 PF.

### What determines power?

Power = Current * Voltage * Power FactorAbove expression can further be explore as :1. For DC CircuitsPower = Current * Voltage2. For Single Phase AC CircuitPower = Current * Voltage * Power Factor3. For Three Phase AC CircuitPower = Line Current * Line Voltage * Power Factor

### What factors determine power?

Power = Current * Voltage * Power FactorAbove expression can further be explore as :1. For DC CircuitsPower = Current * Voltage2. For Single Phase AC CircuitPower = Current * Voltage * Power Factor3. For Three Phase AC CircuitPower = Line Current * Line Voltage * Power Factor

### What is the active power consumed by pure inductive reactance?

The active power of an inductor is zero. As we know, the active power is the result of product of supply voltage and in-phase component of load current. But the load current in pure inductive load lags supply voltage by 90 degrees. So there is no component of load current that is in-phase with the supply voltage. Therefore, the active power in inductive reactance is zero.

### How do you get 347V?

347V can be obtained from a three-phase power system, where the phase-to-phase voltage is 347V. This typically involves connecting three alternating current power lines that are 120 degrees out of phase with each other to create a three-phase circuit, which results in a higher voltage output than a single-phase system.