Pre-Test 1 - Spring 2006

1. A load is absorbing a complex power of S = 15 + j18 VA. The voltage across the load is VL = 1000° (rms).

Answer the following questions.

  1. What is the impedance of the load, ZL?
  2. What is the power factor?
  3. Is the power factor leading or lagging?
  4. What is the current through the load. IL?
  5. What is the average power?
  6. What is the apparent power?
  7. What is the reactive power?
  8. Is the load absorbing or delivering magnetizing vars?
  9. Which of the following is an appropriate model for the load?



  10. What is the peak value of the voltage VL?
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2. Convert the balanced D-D connected 3-phase circuit shown to a balanced Y-Y connected 3-phase circuit.
Find the following:
  1. VAB
  2. VCA
  3. IbB
  4. Ica
  5. Find the total power absorbed by the load.
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3. Write a set of mesh equations which, if solved, would yield values for the mesh currents. You DO NOT have to simplify or solve the equations, but your final set of equations should contain ONLY the mesh current variables shown on the diagram.
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4. Determine the Thevenin equivalent for the circuit shown. Be sure to indicate terminals A and B on your final diagram.
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5. Write a set of nodal equations which, if solved, would yield values for the node voltages. You DO NOT have to simplify or solve the equations, but your final set of equations should contain ONLY the node voltage variables shown on the diagram.
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