Mastering Three-Phase Circuits: Practice Problems and Solutions
School
University of North Dakota**We aren't endorsed by this school
Course
EECS 313
Subject
Electrical Engineering
Date
Dec 12, 2024
Pages
8
Uploaded by ChancellorFlower15430
EE313 Practice Problems ------------------------------------------------------------------------------------------------ --------------------------------------------------------------------------------------------------
a) Determine the phase sequence of the set of voltages van= 200 cos (ωt + 10 °), vbn= 200 cos (ωt - 230 °), vcn= 200 cos (ωt - 110 °). b) Given that Vbn=110∠30° V, find Van andVcn, assuming a positive sequence. c) A balanced three-phase Δ-connected load is fed from a balanced three-phase circuit. The reference for the b-phase line current is toward the load. The value of the current in the b-phase is 12 ∠65°A. If the phase sequence is negative, what is the value of IAB. -------------------------------------------------------------------------------------------------- The magnitude of the phase voltage of an ideal balanced three-phase Y-connected source is 125 V. The source is connected to a balanced Y-connected load by a distribution line that has an impedance of 0.1 + j0.8 Ω/ϕ.The load impedance is 19.9 + j14.2 Ω/ϕ.The phase sequence of the source is acb. Use the a-phase voltage of the source as the reference. Draw the single-phase equivalent for the a-phase. Specify the magnitude and phase angle of the following quantities: a.The three-line currents, b.The three-line voltages at the source, c.The three phase voltages at the load, and d.The three-line voltages at the load. -------------------------------------------------------------------------------------------------- A balanced, three-phase circuit is characterized as follows: • Y- Δ connected;• Source voltage in the b-phase is 150∠135° V; • Source phase sequence is acb; • Line impedance is 2 + j3Ω/ϕ; • Load impedance is 129 + j 171 Ω/ϕ. a) Draw the single-phase equivalent for the a-phase. b) Calculate three line currents. c) Calculate the line voltages at the load. d) Calculate the phase currents at the load. e) Calculate the line voltages at the source.
------------------------------------------------------------------------------------------------------------------------------- Two magnetically coupled coils have self-inductances of 60 mH and 9.6 mH, respectively. The mutual inductance between the coils is 22.8 mH. a) What is the coefficient of coupling? b)For these two coils, what is the largest value that M can have? c)Assume that the physical structure of these coupled coils is such that P1 = P2. What is the turns ratio N1/N2if N1is the number of turns on the 60 mH coil? -------------------------------------------------------------------------------------------------- For the three coupled coils in Fig. 1, calculate the total inductance. Fig. 1 -------------------------------------------------------------------------------------------------- Determine the phasor currents I1and I2in the circuit of Fig. 2. Fig. 2 -------------------------------------------------------------------------------------------------- Two coils are mutually coupled, with L1= 25 mH, L2= 60 mH, and k = 0.5. Calculate the maximum possible equivalent inductance if: (a) the two coils are connected in series (b) the coils are connected in parallel. -------------------------------------------------------------------------------
For the circuit in Fig. 3, find Vo. Fig. 3 ------------------------------------------------------------------------------------------------------------ Two magnetically coupled coils have self-inductances of 60 mH and 9.6 mH, respectively. The mutual inductance between the coils is 22.8 mH. a) What is the coefficient of coupling? b) For these two coils, what is the largest value that M can have? c) Assume that the physical structure of these coupled coils is such that P1=P2. What is the turns ratio if is the number of turns on the 60 mH coil? Find the voltages and currents in the ideal transformer circuit of figure shown below. ---------------------------------------------------------------------------------------------------------- Identify the symmetry in the given waveform and find the Fourier series. + ALL HOMEWORK PROBLEMS