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# Power Engineering

Power engineering is a subfield of electrical engineering that looks at the transmission and distribution of electric power and the electrical devices connected to such systems such as, generators, motors and transformers. Many fields are concerned with the problems of three-phase AC power; the standard for large-scale power transmission and distribution across the modern world.

Electric power is the mathematical product of two quantities: current and voltage. These quantities can vary with respect to time (AC) or they can be kept at a constant level (DC). Most refrigerators, air conditioners, pumps and industrial machinery use AC power; whereas digital equipment uses DC power. AC power has the benefit of being easy to transform between voltages and is able to be generated and utilised by brushless machinery. DC power remains the practical choice in digital systems and can be more economical to transmit over long distances at high voltages.

Power engineering looks at the generation, transmission and distribution of electricity and the design of a range of related devices. These include transformers, electric generators, electric motors and power electronics. Power engineers also work on systems that do not connect to the grid. These systems are called off-grid power systems and may be used in preference to on-grid systems for a variety of reasons.

### Switch Mode Power Supply

Explain how a switch more power supply works. What are its advantages and disadvantages over a linear regulator power supply.

### Relaibility analysis Normal Distribution &Lognormal distribution

1. Five percent of a certain grade of tires wear our before 25,000 miles, and another 5 percent of tires exceed 35,000 miles. Determine the tire reliability at 24,000 miles if wearout is normally distributed. 2. The wearout of a machine part has a lognormal distribution with s=0.5 and t_med=5,630 hours. What is MTTF?

### DC power supply design

Q1. A 9 V power supply delivers 2 A to a resistive load. The a.c. supply is 230 V, 50 Hz and a bridge rectifier is used in conjunction with a 0. 047 farad reservoir capacitor. Estimate: (a) The peak-to-peak ripple voltage. (b) The transformer secondary voltage if the total forward voltage drop in the rectifier is 2 V at 2 A.

### Oscillators including Armstrong Oscillator

See attachment for diagrams. 1. With reference to the block diagram of FIGURE 1, state the two conditions that must be satisfied to give an oscillatory output. FIG. 1 2. With reference to the block diagram of FIGURE 1, determine the required value of G to give an oscillatory output if H = -10 dB. 3. FIGURE 2 shows a p

### Fourier Analysis of Time domain waveform using Excel and THD

Attached are images for questions regarding Fourier Analysis. Q3. Preamble Techniques involving the electronic control of power to a load such as controlled rectification and variable frequency drives are widely used by industry. There can be, however, serious problems with these techniques because of the generation of har

### Power Systems Theory Definitions and Formulas

Hi there, I need some help in these define and state questions Define (a) The fault level of a system or unit in a system (b) base MVA State (c) the equation for percentage impedance or impedance voltage (d) the relationship between X% and Xpu (e) the units of X% and Xpu (f) Xpu in terms of the fault level MVA and th

### Electrical Supply and Distribution Systems

Attached are some examples of the questions I am working through, could you please give fully explained and worked out answers as previous help given and indicate the number of credits that would be sufficient.

### JFET Circuit Amplifier

The attached figure shows an amplifier circuit. - Sketch the small-signal equivalent circuit of the amplifier and use it to estimate the voltage gain. - Attempt to calculate the quiescent value of VOUT. Hint : Apply the appropriate equation: IDS=2xIDSS/Vp^2(VDS[VGS-VP]-VDS^2/2) Or IDS = IDSS(1-VGS

### Single Phase Circuit

A resistor and a capacitor are connected in series across a 150 V a.c supply. When the frequency is 40 Hz the current is 5 A, and when the frequency is 50 Hz the current is 6 A. Find the resistance and capacitance of the resistor and capacitor respectively. If they are now connected in parallel across the 150 V supply, find t

### Power Level for Attenuator

An attenuator has an attenuation of 20 dB over the frequency range 10 MHz to 1.0 GHz. A signal at the input of the attenuator has a frequency of 250 MHz and a power level of - 10 dBW. What is the power level at the output of the attenuator in dBm?

### Two Port Network is used to model the transmission line.

Note: The Solution is handwritten. FIGURE 3(a) represents a 50 Hz, three-phase, high-voltage, transmission line. For one phase, the relationships between the sending end voltage and current and the receiving end voltage are given by the complex ABCD equations: where VS is the sending-end voltage, IS the sending-end current

### Determining the transmit power

The signal to noise ratio at the receiver is required to be at least 17 dB. The average noise power at the receiver is 1 mW. The cable loss between the transmitter and the receiver is 2.5 dB/km and there is 55 km of cable between the transmitter and the receiver. There is a 25 dB amplifier between the transmitter and receiver. D

Error correcting codes are widely used on satellite links that have a low overall CNR in the receiver. A particular link has a clear air overall CNR of 11.0 dB and overall CNR of 6.0 dB when rain is in the downlink path. The receiver implementation margin is 0.5 dB. Modulation on the link is BPSK. The following questions a

### Full-wave rectified signal - MATLAB

Please see attachment for complete question. Consider the full-wave rectified signal y(t) = | sin(PI t) | - Infinity < t < Infinity . (a) As a periodic signal, y(t) does not have finite energy, but it has a finite power Py. Find it. (b) It is always useful to get a quick estimate of the power of a periodic

### Interpreting frequency domain signal spectrum to time domain

A spectrum analyzer is connected to an unknown signal. The spectrum analyzer displays the voltage level of signals in volts vertically and frequency horizontally. The spectrum of the unknown signal creates the following display: A vertical line at a frequency of 50 kHz with a magnitude of 1.80 V A vertical line at a fr

### Power Level of the Attenuator

An attenuator has an attenuation of 20 dB over the frequency range 100r MHz to 1.0 GHz. A signal at the input of the attenuator has a frequency of 450 MHz and a power level of 10 dBW. What is the power level at the output of the attenuator in dBm?

### AC Circit analysis and max power transfer

1. If the output impedance of a certain driving circuit is 50 Ohm - j10 Ohm, what value of load impedance will result in the maximum power to the load? 2. In a first order RC high-pass filter, XC = 500 ohms and R = 2.2 kohms. What is the output voltage (Vout) when the input voltage (Vin) = 10 V.

### Transformer Winding Regulation

A 415V to 11 kV transformer has a rating of 200 kVA. The winding resistance and leakage reactance when referred to the primary are 0.014 and 0.057 ohms respectively. (a) Determine the % regulation of the transformer at 0.8 power factor lagging. (b) In designing a particular 415V to 11 kV, 200 kVA transformer, the primary w

### Frequency modulation

1. What type of signal is represented by the code 15A3? 2. Briefly explain the difference between phase and frequency modulation. 3. A 15 mV sinusoid with input frequency 450 Hz is applied to an FM generator with k = 1000 Hz/20 mV. Find the positive frequency deviation. 4. An FM signal is given by e = 40 sin (2Æ'Ã? ~106t

### Power Factor Phasor Diagrams

The phase schematic diagram in the attachment, shows an 11 kV, 50 Hz, 3-phase, short line feeding a load. By constructing the phasor diagram (use a scale of 1 mm = 2 A) for the load current with V_R as reference, determine the capacitive current and * calculate the capacitive reactance/ph such that the load power factor is in

### Solutions of posed Qs on ADC, Sampling and Transmission

An audio signal has frequencies between 100 Hz and 12 kHz. It is sampled and converted to a digital bit stream using an 8 bit A/D converter. The digital signal is sent to a receiver that converts the signal back to its original analog form. a. Calculate the lowest sampling frequency that can be used in practice. b.

### Find the power dissipated.

A signal generator outputs a sine wave signal with a frequency of 1000 Hz and an rms voltage of 20.0 V. The output of the spectrum analyzer is connected to a 200 ohm resistor. a. What is the power dissipated in the 200 ohm resistor in watts, in dBW, and in dBm? b. An amplifier with a gain of 15 dB over the frequency ra

### RMS current, Power dissipated, Resonant frequency

A circuit consists of a sine wave signal generator and a reactive component (L or C). The output of the generator is a sine wave with a peak amplitude of 8.8 volts at a frequency of 10.0 kHz. a. The generator is connected to an inductor with L = 10.0 mH. What is the rms current flowing in the inductor? b. The generator

### Spectrum Analyzer: Signal Waveforms

A spectrum analyzer is connected to an unknown signal. The spectrum analyzer displays the power level of signals in dBm vertically and frequency horizontally. The spectrum of the unknown signal creates the following display: A vertical line at -6 dBm at 0 Hz (DC), A vertical line at a frequency of 10 kHz with a power level

### Analysing an RF splitter and power levels

A splitter is a device that has a single input and several outputs. It is used to send a signal to several different locations. For example, your apartment or house might have cable TV that delivers a wideband signal via a coaxial cable. A splitter can be used to send the same signal to different rooms so that individual TV se

### Determining the Output Power Level of the Attenuator

An attenuator has an attenuation of 10 dB over the frequency range 10 MHz to 1.0 GHz. A signal at the input of the attenuator has a frequency of 257 MHz and a power level of 10 dBW. What is the power level at the output of the attenuator in dBm?

### Determining the Radius of a Model Earth From Scale Data

The analog to digital converter (ADC) used in a telephone system outputs 8 bit words. The digital words are transmitted as a serial stream to form a PCM voice signal. The analog voice signal voltage always lies between -1.0 V and + 1.0 V. a. Assuming that ADC is linear, what is the step size between quantization levels? b.

### RMS power, RMS voltage, Impedance, Inductive reactance

Please show relevant steps taken to arrive at final answer. 1. The voltage across a load is v(t) = 260 sin (377t + 10 °) and the current through the load is i = 100 sin (377t + 10°). What is the RMS power? 2. The voltage across a load is v(t) = 260 sin (377t + 10 °). What is the RMS voltage? 3. The voltage across a

### A T-attenuator is required to be inserted between an amplifier and a transmission line.

A T-attenuator is required to be inserted between an amplifier and a transmission line. The power level to the line is required to be restricted to -3 dB. The gain of the amplifier is fixed at 24 dB and its maximum input signal is at a level of -10 dB. Sketch a block diagram of the arrangement and calculate suitable values of