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WorksheetsPhasor Diagram and Phase Shift Example
Total questions: 22
Worksheet time: 19mins
Fill in the blank: Power in VARs in lagging phase angle is associated with ______ load.
lagging
leading
resistive
capacitive
Using the formula P = E_LL * I * √3 * cos θ, calculate the power if E_LL = 400V, I = 10A, and θ = 30 degrees.
2000 W
3464 W
4000 W
6000 W
What type of transformer connection is shown in the diagram?
Delta on the low side
Delta on the high side
Wye on the high side
Wye on the low side
Fill in the blank: A phase shift of ___ degrees, current on the delta (high side, Ia) side leads current on the wye (low side, IA) side of the transformer.
30
15
45
60
What is the phase angle relationship across a delta-wye transformer bank?
0 degrees
30 degrees
60 degrees
90 degrees
What is the formula for calculating power (W) using current (I) and voltage (V)?
P = I × V
P = V / I
P = I / V
P=V×I2
In a DC series circuit, how is the total resistance (R_T) calculated?
By summing up all the individual resistances
By multiplying all the individual resistances
By taking the reciprocal of the sum of the reciprocals of all individual resistances
By subtracting the smallest resistance from the largest resistance
What is the formula for inductive reactance (X_L)?
The formula for inductive reactance (X_L) is X_L = 2πfL, where f is the frequency in hertz and L is the inductance in henries.
The formula for inductive reactance (X_L) is X_L = f/L, where f is the frequency in hertz and L is the inductance in henries.
The formula for inductive reactance (X_L) is X_L = L/2πf, where f is the frequency in hertz and L is the inductance in henries.
The formula for inductive reactance (X_L) is X_L = 1/2πfL, where f is the frequency in hertz and L is the inductance in henries.
Which of the following is the correct formula for capacitive reactance (X_C)?
X_C = 2πfC
X_C = 1/2πfC
X_C = 2πfL
X_C = 1/2πfL
In a DC parallel circuit, how is the total voltage (V_T) related to the individual voltages (V_1, V_2, V_3)?
The total voltage (V_T) in a DC parallel circuit is equal to the individual voltages (V_1, V_2, V_3), meaning V_T = V_1 = V_2 = V_3.
The total voltage (V_T) is the sum of the individual voltages, meaning V_T = V_1 + V_2 + V_3.
The total voltage (V_T) is the average of the individual voltages, meaning V_T = (V_1 + V_2 + V_3) / 3.
The total voltage (V_T) is zero if any of the individual voltages is zero.
What is the phase relationship between current and voltage in a resistive load?
In an inductive load, how does the current relate to the voltage?
In a capacitive load, the current ______ the voltage by 90 degrees.
leads
lags
is in phase with
is opposite to
What happens to the current in a combination of resistive and inductive load?
Refer to the typical balanced 3 phase current waveform and equivalent phasor diagram shown in fig. 2. What is the phase relationship between the currents using the phasor diagram (fig. 2b)?
C1 leads C2 by 120 degrees and C1 leads C3 by 240 degrees.
C1 leads C2 by 90 degrees and C1 leads C3 by 180 degrees.
C1 leads C2 by 60 degrees and C1 leads C3 by 120 degrees.
Explain how phasors can be added or subtracted. Use the example of finding the voltage Vab as described in the text.
Phasors can be added or subtracted by converting them to rectangular form, performing the addition or subtraction, and then converting back to polar form.
Phasors can be added or subtracted by simply adding or subtracting their magnitudes and angles directly.
Phasors can be added or subtracted by using the cross product of the vectors.
Phasors can be added or subtracted by using the dot product of the vectors.
What does Figure 3 show in terms of phasor relationships?
Figure 3 shows the magnitude of phasors.
Figure 3 shows the phase angle between phasors.
Figure 3 shows the addition of phasors.
Figure 3 shows the subtraction of phasors.
What is a phasor defined as?
A complex number representing a sinusoidal function
A type of laser used in physics experiments
A unit of electrical resistance
A mathematical tool used in calculus
The purpose of phasor diagrams is to:
represent sinusoidal functions as rotating vectors
solve linear equations
depict chemical reactions
illustrate historical events
Consider the voltage and current sine waves shown in fig. 1. What is difficult to determine from these waves?
The phase difference between the waves
The amplitude of the waves
The frequency of the waves
The type of the waves
What does the length of an arrow represent in phasor diagrams?
The length of an arrow in phasor diagrams represents the magnitude of the quantity being depicted, such as voltage or current.
The length of an arrow in phasor diagrams represents the phase angle of the quantity being depicted.
The length of an arrow in phasor diagrams represents the frequency of the quantity being depicted.
The length of an arrow in phasor diagrams represents the direction of the quantity being depicted.
Which of the following is a rule for phasor diagrams?
Use closed arrow heads for voltage phasors
Use open arrow heads for current phasors
Only sinusoidal waveforms allowed
Frequency of arrows can vary
