Chapter 5 Flashcards
What is the equation for sinusoidal voltage? Define all terms
Vmcos(Wt+@)
Vm = peak voltage, W(omega) = angular frequency, @(theeta) = phase angle
What is the equation for W(omega)?
W = 2pi/ T
If you are given a sinusoidal voltage in terms of sin, what must you do? How?
Change it in terms of cos
sin(z) = cos(z-90)
RMS) What is the equation for the average power?
V^2rms/ R
What is the equation for Vrms?
Vm/ sqt2
How do you calculate the phase angle?
360 x f x /\t
If a sinusoidal voltage is given by Vcos(Wt + @), what is the corresponding phasor?
V/_@
For a pure inductance does current lag or lead voltage? By how much?
Current lags the voltage by 90
What is KVL in phasor form?
The sum of the phasor voltages equals zero for any closed path
What is KCL in phasor form?
The sum of the phasor currents entering a node must equal the sum of the phasor currents leaving the node
What is the equation for power for a pure resistance load?
p(t) = VmIm.cos^2.(Wt)
What is the equation for power for a pure inductance load?
p(t) = VmIm/ 2.sin(2Wt)
What is the equation for power for a pure capacitance load?
p(t) = -VmIm/2.sin(2Wt)
For a pure resistance load, what phase are V and I in?
In phase
For a pure resistance load, is power positive or negative? What does this mean?
Power is positive
Energy flows from the source to the load
For a pure inductance load, what phase are V and I in?
I lags V by 90
For a pure inductance load, is power positive or negative? What does this mean?
Power is both positive and negative
When power is positive, energy is delivered to the inductance source
When power is negative, inductance returns energy to the source
For a pure capacitance load, what phase are V and I in?
I leads V by 90
For a pure capacitance load, is power positive or negative? What does this mean
Power is both positive and negative
When power is positive, energy is delivered to the capacitance source
When power is negative, capacitance returns energy to the source
If the reactive power is positive, what direction does it flow?
Source to load
If the reactive power is negative, what direction does it flow?
Load to source
What load has a positive reactive power?
Inductance
What load has a negative reactive power?
Capacitance
What is the equation for power for a general load?
P = VrmsIrms.cos(@) @ = theeta
What is the equation for power factor
PF = cos(@) @ = theeta
What is the power angle?
@v -@i
@ = theeta
What is the equation for reactive power?
Q = VrmsIrms.sin(@) Q = reactive power, @ = theeta
What is the unit for reactive power?
VAR, volt ampere reactive
What is the equation for apparent power?
AP = VrmsIrms
What is the unit for apparent power?
VA
What is the equation for complex power?
S - 1/2. VI
S = complex power, V = phasor voltage, I = phasor current
