Challenging Engineering Problems with Detailed Answers

(20 pts). The voltage across the terminals of a 1500000 pF (pF = picofarads = 1.0E-12 -15,000/ farads) capacitor is: v=30e sin 30,000 t V for t20. Find the current across the capacitor for t0.
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4. (20 pts). For the following circuit, calculate the value of Zn (Thvenin impedance). 2.5 F 4 mH Z 40 0
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x(t) 10 5 1 2 t 1) Compute Laplace transform for the above signal. 2) By using a suitable Laplace transform properties, evaluate the laplace transform if the signal is shifted to the right by 10sec.
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A sinusoid carrier signal c(t) is defined as: c(t) = 5 cos(10,000ft) A message signal is modulating the above carrier in AM system, expressed as: m(t) = 2 cos(104nt) a) Find Modulation Index "u". b) Find the B.W of the Base Band signal. c) Find the B.W of the Band Pass signal. d) What is the FL FH and Fc for the band pass signal.
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d) Sketch the construction an op-amp circuit with an input resistance of 10 KOhm which performs the following calculation: Vout= -1000 Vin dt
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Let the following LTI system This system is jw r(t) H(jw) = 27% w y(t) 1) A high pass filter 2) A low pass filter 3) A band pass filter 4) A stop pass filter
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(20 pts). For the following circuit, calculate the value of Zh (Thvenin impedance). 2.5 F 4 mH HE Z 40 Q
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Consider the following three Linear Time Invariant (LTI) systems connected as shown in Figure 1 below: x[n] and h [n] h[n] h[n] Figure 1 a. The impulse response of each block is given by: 6 6 + h [n] = 0.48[n] + 8[n - 1] +0.28[n-2], h [n] = 8[n] +0.58[n 1], y[n] h [n] = 0.68[n] + 0.8 8[n 1] -0.2 8[n-2] -0.6 8[n-3] Find the overall system impulse response h,[n]. (10 marks) b. Find the system transfer function H(2), and evaluate H(e) at WT = 0, 2 4 , I. (8 marks) c. Sketch |H(ej) | vs WT for 0 T n. Is it a high-pass, bandpass or a low-pass filter? (4 marks) d. Is the system stable, and why?
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As an engineer for a private contracting company, you are required to test some dry-type transformers to ensure they are functional. The nameplates indicate that all the transformers are 1.2 kVA, 120/480 V single phase dry type. (a) With the aid of a suitable diagram, outline the tests you would conduct to determine the equivalent circuit parameters of the single-phase transformers. (6 marks) (b) The No-Load and Short Circuit tests were conducted on a transformer and the following results were obtained. No Load Test: Input Voltage = 120 V, Input Power = 60 W, Input Current = 0.8 A Short Circuit Test (high voltage side short circuited): Input Voltage = 10 V, Input Power = 30 W, Input Current = 6.0 A Calculate R, X, R and X (6 marks) m eq eq (c) You are expected to predict the transformers' performance under loading conditions for a particular installation. According to the load detail, each transformer will be loaded by 80% of its rated value at 0.8 power factor lag. If the input voltage on the high voltage side is maintained at 480 V, calculate: i) The output voltage on the secondary side (4 marks) ii) The regulation at this load (2 marks) iii) The efficiency at this load
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A single phase transformer steps down from 2000/400V.it has a primary resistance of 0.1792 and a secondary of 0.006892.the reactance are 0.2552 and 0.0102 respectively. Calculate the resistance, reactance and impedance referred to the secondary. Hence find the percentage regulation on full secondary load of 250A at a P.f of 0.8 lagging.
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Exercise 1 - A single-phase distribution transformer with 75kVA, 240V:7970Vand 60 Hz has the following parameters referred to the high voltage side:R1 = 5.93 ; X1 = 43.2 ; R2 = 3.39 ; X2 = 40.6 ; Rc = 244 k; Xm = 114 kCalculate the efficiency and voltage regulation of this transformer when it supplies aload with a power of 75 kVA and a power factor of 0.94.
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DI is a Zener diode with V-0.7V and Vzx-5V, and D is a pn junction diode with V-0.7V. Both are ideal diodes. (1) When V-8V, calculate VDI, IDI, VD, ID2, and It. (2) When V-12V, calculate VDI, IDI, VD2, ID, and I. (Hint: Determine the states of the diodes first in each case.) 3 3 kn I V* VDI V Ipt D D Ipa *V2
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A system with input r(t) and output y(t) is described by y" (t) + y(t) = x(t) This system is 1) Stable 2) Marginally stable 3) Unstable
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Design a BJT (npn) CE amplifier circuit for the following specifications Voltage Gain Av 50, Assume Re is fully bypassed. A Input Resistance Ri 24k R = 8k2 Load resistance Supply voltage Vcc=20V Input internal resistance Rs 0 52. Given transistor parameters B-150, and VBE=0.65V. Find all the transistor bias resistors: R, R, RC, RE. Find the operating points (le and Ver.) Draw the amplifier circuit with all resistor values
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(20 pts). The voltage across the terminals of a 1500000 pF (pF = picofarads = 1.0E-12 farads) capacitor is: v=30 e - 15,000r sin 30,000 t V for t20. Find the current across the capacitor for t0.
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For a n-JFET CS amplifier circuit with the following values: VDD 18V, RL -20 ks2, R = 60 ks2, R = 80 k2, Rp 12k2, Rss = 1 k2, Rs = 10052 (source internal resistance). Assume Ipss=20mA and V - 4.0 V. Assume Rss is fully bypassed. Given the equation for A, as following: a. Find the operating points Ip, Vos and VDs b. Find the ac voltage gain A,: [ The equation is: [A] = gm Ra (RD|R)/(Rs+RG)] c. The input Resistance Ri d. Draw the ac equivalent circuit using a JFET ac model
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A single-phase half-wave converter in Figure 10.1a is operated from a 120-V, 60-Hz supply. If the load resistive load is R = 10 and the delay angle is a = ficiency, (b) the form factor, (c) the ripple factor, (d) the transformer utilization factor, and T/3, determine (a) the ef- (e) the peak inverse voltage (PIV) of thyristor T,
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The water utility requested a supply from the electric utility to one of their newly built pump houses. The pumps require a 400V three phase and 230V single phase supply. The load detail submitted indicates a total load demand of 180 kVA. As a distribution engineer employed with the electric utility, you are asked to consult with the customer before the supply is connected and energized. i) With the aid of a suitable, labelled circuit diagram, explain how the different voltage levels are obtained from the 12kV distribution lines. (7 marks) ii) State the typical current limit for this application, calculate the corresponding KVA limit for the utility supply mentioned in part i) and inform the customer of the repercussions if this limit is exceeded. (7 marks) iii) What option would the utility provide the customer for metering based on the demand given in the load detail? (3 marks) iv) What metering considerations must be made if this load demand increases by 100% in the future?
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The water utility requested a supply from the electric utility to one of their newly built pump houses. The pumps require a 400V three phase and 230V single phase supply. The load detail submitted indicates a total load demand of 180 kVA. As a distribution engineer employed with the electric utility, you are asked to consult with the customer before the supply is connected and energized. i) With the aid of a suitable, labelled circuit diagram, explain how the different voltage levels are obtained from the 12kV distribution lines. (7 marks) ii) State the typical current limit for this application, calculate the corresponding kVA limit for the utility supply mentioned in part i) and inform the customer of the (7 marks) repercussions if this limit is exceeded. iii) What option would the utility provide the customer for metering based on the demand given in the load detail? (3 marks) iv) What metering considerations must be made if this load demand increases by 100% (2 marks) in the future?
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Choose one answer. An LTI system's transfer function is represented by H(s) = . If unit step signal is applied at the input of this system, corresponding output will be S 1) Sinc function 2) Cosine function 3) Unit impulse 4) Unit ramp function
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2. Use PSpice to find the Thevenin equivalent of the circuit shown below as seen from terminals abl 109 -j4 40/45 V (1)8/0 A 5 4
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As an engineer for a private contracting company, you are required to test some dry-type transformers to ensure they are functional. The nameplates indicate that all the transformers are 1.2 kVA, 120/480 V single phase dry type. (a) With the aid of a suitable diagram, outline the tests you would conduct to determine the equivalent circuit parameters of the single-phase transformers. (6 marks) (b) The No-Load and Short Circuit tests were conducted on a transformer and the following results were obtained. No Load Test: Input Voltage = 120 V, Input Power = 60 W, Input Current = 0.8 A Short Circuit Test (high voltage side short circuited): Input Voltage = 10 V, Input Power = 30 W, Input Current = 6.0 A Calculate R, X, R and X (6 marks) eq eq (c) You are expected to predict the transformers' performance under loading conditions for a particular installation. According to the load detail, each transformer will be loaded by 80% of its rated value at 0.8 power factor lag. If the input voltage on the high voltage side is maintained at 480 V, calculate: i) The output voltage on the secondary side (4 marks) ii) The regulation at this load (2 marks) (4 marks) iii) The efficiency at this load (d) The company electrician wants to utilize three of these single-phase dry type transformers for a three-phase commercial installation. Sketch how these transformers would be connected to achieve a delta-wye three phase transformer.
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When the phase voltage of a three-phase propagation diode rectifier as shown in [Figure 3-17] is a sine wave with a phase voltage of 220 [V], 60 [Hz], and the load resistance is 20 [Yo], find the following: (a) Average value of output voltage (b) Average value of output current (c) Effective value of the output current (d) Power consumed by the load (e) Power factor 0 0 DE PUB 11 10/ Ut I 1 T A DoDo : D&DI DD Vo 0 ATV3 (Figure 3-17] Three-phase radio diode rectifier Ven Ube D a D (a) a circuit diagram 1 1 i D H b Do Uca 1 ! i 2 D5 D Ven Ub 1 1 ! H H ! H + H + 1 1 1 1 1 1 1 I DD3 D&D, D,D5 D5D6 D6D Ube Uca Ucb (b) Waveforms 1 1 + : SR DD 1 -
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To ensure the yield of the integrated circuit, a strong design is made for PVT fluctuations. Explain how to verify the change in MOSFET characteristics according to the process change
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