# Questions tagged [real-power]

Power dissipated by a load is referred to as true power. True power is symbolized by the letter P and is measured in the unit of Watts (W). The formula for Real power is I²*R or V²/R.

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### Calculating Real Power Dissipation in a Series RC Circuit

Given circuit: simulate this circuit – Schematic created using CircuitLab Question: What is the real power dissipated in the resistor of the given circuit? My Solution: Note: I am calculating ...
1 vote
137 views

### Reactive power calculation: what did I do wrong?

I calculated the question and I did not get the same answer as in the book. Could someone please explain why my method is not correct? Question: My solution: Book solution: The problem is from the ...
82 views

### What is the real and apparent power of these steel cutters?

The US market model of this steel cutter is 120 VAC, 13.0 Amp. The NZ market model is 230 VAC, 1,100 W. I am trying to wrap my head around whether 1,100 W is the real power and so whether the apparent ...
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960 views

### How does negative (or export) kVAR and kW affect maximum demand charges?

I am trying to calculate enegy costs using data from an energy meter that provides me with halfhourly data points for the following 4 channels: Import kW Export kW Import kVAr Export kVAr and in ...
228 views

### Short circuit analysis

Im given the next distribution line with a generator and a load The generator is set at $23\,kV$ the line impedance is $9.5\Omega +j19.055\Omega$ and the aparent power is $1.5MW+j2MVars$ in the ...
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1 vote
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### What does mean if there is P+ and Q-?

If in a circuit there is real power positive and reactive power negative, what does mean in terms of power flow? I undestand that the real power is produced in the generator/source and goes to the ...
• 495
1 vote
648 views

### Angle difference of source/load for real power flow

simulate this circuit – Schematic created using CircuitLab Suppose Vs = |Vs| (angle 0) and Vload = |Vload|exp(jθ). 'Because Vs has an angle of 0, θ must be negative in order for real power (P) ...
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### Is reactive power periodic in nature? What is the exact difference between active power, average power, and real power?

Consider an RC circuit which is supplied by a sine source $$v(t)=V_m\cdot \sin(\omega t)$$ The current through the circuit will be i(t)=I_m\cdot \sin(\omega t+\phi) \\ \phi=\arctan \left(\dfrac{1}{\...
6k views

### Do circuit breakers trip on Apparent or True Power?

The thermal and magnetic protection for AC circuit breakers take into account both the timing and the magnitude of the AC current passing through. Does a standard circuit breaker trip on the current ...
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### What is the significance of UPS output power factor?

A UPS's output rating is shown as 2000VA/1800W. I understand that the power factor here is 0.9, but the device or load I will connect to the UPS might have pf<0.9 or pf=1 (for light bulb.) From my ...
1 vote
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### What are the exact meanings of reactive and apparent powers? Do we say they are supplied or consumed?

(The following doubt is from the topic of Sinusoidal Steady-State Analysis of electrical circuits) I understand the meaning of real power - it is the average power consumed (or delivered) by an ...
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### Where am I wrong about my calculation of power loss?

The power loss of circuit is $16kW$ when the power factor, PF, is 0.6 lag. Now if I improve the PF from $0.6$ lag to $0.8$ lag, what is the power loss now? The solution provide me the formula ...
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756 views

### Is there a mathematical proof that reactive power regulates voltage?

So after studying the power triangle and trying to conceptualize real power and reactive power, I seem to have come across a contradiction, at least in my own head. Most explanations disregard ...
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### Reactive vs Real Power in DC-DC Converters

I don't understand which form of power, reactive or real, should be dominant in a maximally efficient DC-DC boost converter. As the circuit charges the inductor, the current and voltage will be out ...
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282 views

### Tool for measuring Real and Reactive Power [closed]

I am currently doing a project where I need the Real power (P) and Reactive power(Q) measurement for a Refrigerator. I understand that if I can measure AC Voltage(V) and AC Current(A) for the ...
516 views

### What is Real Power (AC circuit)?

I've beenstudying Real(True), Active and Apparent power in AC circuit. I have understood all the concepts including phasor diagram, lagged sinusoidal waveform,the relationship between those three ...
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### Calculating the real and reactive power of a transmission line

I have a single machine connected to an infinite bus with the following parameters: Sending end power = 3.75MW RL=5.18 ohms XL=130 ohms VS (Generator bus)=161kV VR (Infinite bus)=161kV Sending end ...
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414 views

### What is the power factor of a classical power supply?

What is the power factor of a classical power supply ? I mean a transformer, rectifier and filter capacitor. Is it constant ?
1 vote
403 views

### Complex power, real power

Given: $U_q = 220 V, f = 50 Hz, R_i=10 \Omega, R_a=40 \Omega, L_a=95.5 mH$ I'm asked to determine the real power transformed in $Z_a$. Here I break down the formulas that I use: \\$Z_{total}=Z_{...
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216 views

### Using Reactive vs Real Power to Manage Distribution System Voltages

This is my first post. The introduction of photovoltaics (PV) on the electrical distribution system creates changes to real power, resulting in voltage fluctuations. Those voltage fluctuations can ...
777 views

### Why do these equations prove that power factor is constant for all circuits in case of sine wave?

I know that I'm missing something but I don't know what I'm missing. Power factor is the ratio between real power and apparent power. So, I will get the equations of real power and apparent power ...
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1 vote
2k views

### calculating the average power using the oscilloscope

I am trying to measure the real power of an inductor, and in the manual it is said that I have to connect a resistor with low resistance to the inductor and then see the voltage difference between the ...
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### How to derive apparent power formula for three phase AC system?

I know that the total power output of a three phase system is √3 EI cosØ Where E and I are the line voltage and line current. Now my question is how can one derive the apparent power equation i.e.. √...
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