Question

Circuits

Q.2 (20 marks) A 2XY-hp, 6 XY-V, 0.85-PF-leading A-connected synchronous motor has an armature resistance of 0.2 Q and a synchronous reactance of 3.7 Q. Its efficiency at full load is 92%. The field current flowing under these conditions is 3.5 A. (where XY are the last two digits of your student ID).

a)What is the input power to the motor at the rated conditions? (2 marks)

b)What are the line and phase currents of the motor at rated conditions and pf? (2 marks)

c) What is the reactive power consumed by or supplied by the motor at rated conditions?(2 marks)

d)What is the internal voltage Ea of this motor at rated conditions? (2 marks)

e)What the converted power and induced torque at rated conditions? (2 marks)

f)If Ea is decreased by 10 percent, how much reactive power will be consumed by or supplied by the motor? (2 marks)

g)How much field current would be required to make the motor operate at 0.85 PF leading? (current magnitude might not necessarily remain the same). (2 marks)

h)If the load on the motor is decreased by 20% of the rated power while the motor operates at unity power factor, what will be the new torque angle? (3 marks)

If the field current was increased by 10 percent, what would the new value of the armature current be? What would the new power factor be? How much reactive power is being consumed or supplied by the motor? (3 marks)

Verified

### Question 52583

Circuits

Problem 3 For the following circuit, use nodal analysis to write the FOUR equations in standard form. DO NOT SOLVE. You must identify any quasi-supernodes, supernodes, auxiliary equations, and remove dependent variables. Your final equations may only have V₁, V2, V3 and/or V4 as unknowns. Put your final equations in standard form in the box provided.

### Question 52582

Circuits

Problem 2 For the following circuit, write the FOUR mesh equations in standard form. DO NOT SOLVE. You must identify any super meshes, auxiliary equations, and re-move all dependent variables. Your equations may only have 11,12,13 and/or 14 as unknowns. Put your final equations in standard form in the box provided.

### Question 52581

Circuits

Problem 1.1 Determine Reg in Ohms at the (a,b) terminals for the following circuit. Round your answer to the nearest single digit decimal place (tenths).
Problem 1.2 Determine the voltage V, in Volts for the following circuit. Round your answer to the nearest single digit decimal place (tenths).
Problem 1.3 Determine the current I, in Amps for the following circuit. Round your answer to the nearest single digit decimal place (tenths).
Problem 1.4 Determine the power, P3n, delivered to the 302 resistor in Watts for the following circuit.Round your answer to the nearest single digit decimal place (tenths).

### Question 45529

Circuits

11) From your answer in (10), does the 4V 'DC' or steady state voltage impact the value of the displacement current, Ic.

### Question 45528

Circuits

\text { 10) Assuming } I_{C}=C \frac{d V_{C}}{d t} \text {, find the displacement current for } V_{C}=e^{-\omega t}+4 V \text { and } V_{C}=
sin(wt) + 4 V.

### Question 45527

Circuits

9) Based on your answer in (7), can you apply an arbitrarily large field or voltage across a dielectric? What is the name for this limitation and what is its value for Air and Glass (SiO2)?

### Question 45526

Circuits

8) Remembering quantum tunneling from Chapter 3, what is happening to the probability of a tunneling event as the "thickness" of the barrier representing the dielectric decreases?

### Question 45525

Circuits

7) What happens to the relative "thickness", or distance an electron must travel in a straight line across the dielectric, as you increase the voltage?

### Question 45524

Circuits

6) Redraw the diagram in (5) with a small positive voltage on the right-hand side (no voltage or OVon the left-hand side).

### Question 45523

Circuits

5) Draw the energy band diagram of a capacitor made of two aluminum plates with a glass dielectric. The capacitor should have zero applied voltage.