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In electrical engineering, when calculating complex power (S = VI*), we use the complex conjugate of the phasor current (I*) because it ensures that the power calculation reflects the correct direction of power flow. The complex conjugate accounts for the phase difference between voltage and current, allowing us to separate real (active) power and reactive power components. This convention aligns with the mathematical properties of complex numbers, ensuring that the resulting power values are consistent with physical interpretations in AC circuits.
What else can I help you with?
Why you take the conjugate of current in complex power?
In order to calculate the complex power of a circuit, the conjugate of current is used. The Vrms of the circuit is multiplied by the complex conjugate of the total circuit current.
Why do you use the conjugate of current to calculate power?
Because the angle of the power phasor is the difference between the one of voltaje and the one of current. As they are multiplied,instead of being added they are substracted
Why current increases with decrease in power factor?
It's easier to answer you question the other way around, that is "Why does the load current fall with an increase in power factor?"Before power-factor improvement, the load current is the phasor (or vector) sum of the load's resistive (IR) and inductive currents (IL).Power-factor improvement is achieved by adding a capacitor in parallel to the load so, after power-factor improvement, the load current becomes the phasor sum of the resistive current (IR), inductive current (IL), and the capacitive current (IC).Since the inductive current and capacitive current are displaced from each other by 180 degrees (i.e. are in antiphase), the the phasor sum of IR + IL +IC will be smaller than the phasor sum of just IR and IL.Hence, the supply current reduces as the power factor improves.
What is a phasor diagram and why you draw it?
Theoretically, it can be drawn at any angle. Normally, however. it is drawn along the real, positive, axis (i.e. facing East). For series circuits, the reference phasor is the current and, for parallel circuits, the reference phasor is the voltage. For transformers, it is the flux.
How do you draw phasor diagram of maxwell bridge?
For Series Circuits (example for R-L circuit)Because current is common throughout a series circuit, current is taken as the phasor of reference for series AC circuits. So, we start by drawing a current phasor at 0o. Since the voltage across a purely resistive component (VR) is in phase with the current, we next draw VR in phase with the reference phasor. Since the voltage across a purely inductive component (VL) leads the current by 90o, we draw VL at 90o. We vectorially add phasors VR and VL to give V, the supply voltage. The angle between V and the reference phasor, I, is the phase angle. To create an impedance diagram, divide each voltage by the reference. To create a power diagram, multiply each voltage by the reference.For Parallel Circuits (example for R-L circuit)Because voltage is common across each branch of a parallel circuit, voltage is taken as the phasor of reference for parallel AC circuits. So, we start by drawing a voltage phasor at 0o. Since the current through a purely resistive branch (IR) is in phase with the voltage, we next draw IR in phase with the reference phasor. Since the current through a purely inductive branch (IL) lags the current by 90o, we draw IL at -90o. We vectorially add phasors IR and IL to give I, the load current. The angle between I and the reference phasor, V, is the phase angle. To create an admittance diagram, divide each current by the reference. To create a power diagram, multiply each current by the reference.
Why is power factor is cos of angle between voltage and current?
Power factor is the ratio of true power to apparent power -if you refer to the so-called 'power triangle', these correspond to the adjacent and hypotenuse of a right-angled triangle. The cosine of the angle between them is the ratio of hypotenuse (apparent power) to adjacent (true power). As the power triangle is derived from the voltage/current phasor diagram, this is exactly the same angle as that between load current and supply voltage.
What is the input signal of key phasor?
The input signal of a key phasor is typically a periodic waveform, such as a sinusoidal signal, used to establish a reference for measuring and analyzing the phase relationship between different signals in power systems. It serves as a synchronization point for phasor measurement units (PMUs) to accurately capture the magnitude and phase of electrical quantities like voltage and current. This reference signal is crucial for applications in monitoring, control, and protection of electrical grids.
Cross-power spectrum of two fourier transform images?
It's (I1./I2*)/(|I1./I2*|), where I2* is the complex conjugate of the Fourier transformed Image 2
What is complex power?
Complex power is a measure of power in an alternating current (AC) circuit that combines both real power and reactive power. It is represented as a complex number, typically denoted by ( S = P + jQ ), where ( P ) is the real power (measured in watts) that performs useful work, and ( Q ) is the reactive power (measured in volt-amperes reactive, or VAR) that oscillates between the source and the load but does no net work. The magnitude of complex power indicates the total power in the system, while the angle provides information about the phase difference between voltage and current.
Sketch and explain the no load phasor diagram of a transfomer?
a.) Io = no load current consists of 5% of the full-load primary current. b.) Iom = magnetising current/component responsible for setting up the magnetising flux in the core. c.) Iol = Ic = power loss component responsible for supplying the core losses and the windings losses.
Is the phasor a time-domain or frequency-domain quantiy?
It is a frequency-domain quantity. In Basic Engineering Circuit Analysis by Irwin, the time domain is written as A*cos(wt+/-THETA) and the frequency domain is written as A*phasor(+/-THETA).A series of phasor measurements, taken at regular intervals over time, can sometimes be useful when studying systems subject to variations in frequency. The electric power system is one example. The power grid nominally operates at 50Hz (or 60Hz), but the actual frequency is constantly changing around this nominal operating point. In this application, each individual phasor measurement represents a frequency domain quantity but a time series of phasor measurements is analyzed using time-domain techniques. (http://en.wikipedia.org/wiki/Synchrophasor)
What is the difference between phase angle and phase difference?
Although we use the term 'Phase angle' it's also an angle referred to another phasor (voltage or current).For example,conventionally when expressing power factor, we use 'voltage' as the reference. So the 'phase angle' of a particular phasor is the phase difference between our reference (voltage) & the phasor.As the gist, both mean the same except that 'phase angle' is the direction of the phasor w.r.t. positive x direction (reference)..AnswerBy definition, phase angle is the angle by which a load current leads or lags a supply voltage.Phase difference is the angle between any two electical quantities -for example, the angle two phase voltages of a three-phase system.
