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Power Engineering

Power Factor Correction

Please show as much working as possible and comment where possible. Two single-phase loads are connected in parallel across a 415 V, 50 Hz supply. One load is rated 130 kW at a power factor of 0.75 and the other is 74 kW at a power factor of 0.6. Determine the capacitor value required to be placed in parallel with the combin

Received power of half-wave dipole antennas

Assume that two antennas are half-wave dipoles and each has a directive gain of 3dB. If the transmitted power is 1W and the two antennas are separated by a distance of 10 km, what is the received power? Assume that the antennas are aligned so that the directive gain numbers are correct and that the frequency used is 100 MHz.

Public Address system howling, Resolution of ADC, Power delivered to the heating system, Power in the load of thyristor circuit, Hydraulic press controlled by a solenoid-operated control valve

Please refer to the attachment for mentioned figures. 2. FIGURE 5 shows a public address (P.A.) system. (a) Represent the P.A. system as an `information system' block diagram. (b) It is found that if the microphone is brought into the proximity of the loudspeaker, the system will `howl'. Carefully explain, making reference

Determining Length of Spark: Example Question

The energy (power) in Watts in an electrical circuit is described by P = VI, where V is volts and I is current. A typical hair dryer consumes 1500 Watts of energy. Household voltage is about 110 volts. If the hair dryer represents 1.5 Henerys of inductance and the plug breaks contact in one millisecond, how long is the spark?

Voltage, Instantaneous Power, Laplace Transforms, Damping

There may be a few characters missing in the questions below but this is what should be used to come up with answers. 1) Determine the Laplace transform of f(t) = +5e^-4t + 12sin 3t. 2) If the voltage across a 2 F capacitor is initially zero, what is the instantaneous power if the current is A? 3) The charge in a certai

Power Factor

Please see the attached file for details. My question is, as seen from the the source Vs, would the impedance need to be completely resistive, including line resistances, so that we we could say Z=R+j0 to get a power factor of unity or 1?

Find the maximum power transfer and resistors in attenuator pads.

1. Find (a) RL for maximum power transfer, and (b) the maximum power transferred to the load 2. Design a pi-section symmetrical attenuator pad to provide a voltage attenuation of 12dB with a characteristic impedance of 600 ohms. 3. Using the Delta-Star transformation, obtain the equivalent T -section symmetrical attenuator

Zener Diode and Series Resistance

In the zener diode circuit calculate the value of the current through the zener diode if the power supply is rated 24 volts at 500 milli amperes. The load voltage is 12 volts and draws a current of 300 milli amperes. Also calculate the value of the series resistance R.

Basic electricity - 3 phase installation powered

Consider the following: A 3 phase installation powered by 400V 50Hz is composed of 6 machines. (Please see the attached table) Find: a) Total apparent power b) Total absorbed current (line current) c) Installation power factor d) The power of the capacitors that should be installed to have a power factor of 0.95 e) Tot

current and average power delivered to the load

A load has a 20 ohm resistor and a 4 henry inductor connected in series. It is connected to a power source with v(t)= 100cos50t, connected in series to the load. What is the impedance, the current, and the average power delivered to the load using the phasor transform method.

Power factor in AC circuit

A single phase electric motor has an output power of 10 kW and an efficiency of 90% at full load. The motor is fed from a 240 V supply via a cable that has a resistance of 10 milli ohms per metre length. If the terminal voltage to the motor must not fall below 90% of the supply voltage, calculate the maximum return length of the

Problem Feeder - Transformer

A single-phase load is supplied through a 35 kV feeder whose impedance is 115 + j380 Ohms and a 35 kV, 2400 V transformer whose equivalent impedance is 0.26 + j1.21 Ohms referred to its low voltage side. The load is 180 kW at 0.87 leading power factor and 2320 V. (a) Compute the voltage at high-voltage terminals of the

maximize this power dissipated by load

See attached file for full problem description. Given the adjacent circuit, with voltage source Vin and source resistance R1, what is the power dissipated across R2? (Remember, P=I^2*R = IV) In terms of R1, what is the value of R2 that will maximize this power (show all work)?

Maximum Power and Value of R: Example Problems

See diagram in attache file. The figure to the left is a voltage source, which has a internal resistance Ri. The figure to the right is a resistor ( R ) (outside the source) 1. What is the maximum power that can be delivered to the load R? 2. What value of R achieves that?

Power Factor Correction

Three parallel impedances in rectangular form as follows: 8.66+j5 ohm , 25+j0 ohm , 3.54+j2.54. A 240 volt 50 Hz supply Calculate overall power factor of the three loads.

Complex Power of a Load

Calculate S, the complex power of a load (in rectangular form), given the following data: Vrms = 220 V, P = 1kW, magnitude of Z = 40 ohm (inductive). a. S = 2000 - j150.3 VA b. S = 1000 + j681.2 VA c. S = 2000 - j681.2 VA d. S = 1000 - j150.3 VA

AM Wave and Power

Consider the message signal: m(t) = 20 cos (2*pi*t) volts and the carrier wave: c(t) = 50 cost(100*pi*t) volts a. Sketch (to scale) the resulting AM wave for 75% of the modulation b. Find the power developed across a load of 100 ohms due to this AM wave.

Power Factor: Solving for Circuits

Determine C so that the plant power factor of Figure P7.25 (see attached file) is corrected to 1 (or the power factor angle to zero) so that Is is minimized and in phase with Vo. vs(t) = 450cos(wt) V w = 377 rad/s Z = 7 < 0.175 &#937;

Maximum Power Theorem

A) Find the Thevenin's circuit for the circuit shown in Fig. 5.1 (see attachment) similar to the circuit shown in Fig. 5.2 (see attachment). b) Calculate the output voltage for different load resistors and the corresponding power and enter these values in Table 1. c) Plot a graph of load resistance vs power using Matlab (

Shunt resistance effect in a voltage divider

What is the effect of the DMM input resistance on the measured results? Derive the voltage gain of the divider with a DMM resistance of Rm, which is also called shunt resistance (See Figure 2.3-attached file).

Capacitance

Prior to t=0, a 100- uF capacitance is uncharged. Starting at t=0, the voltage across the capacitor is increased linearly with time to 100V in 2s. Then, the voltage remains constant at 100V. Sketch the voltage, current, power, and stored energy to scale versus time. Please show equations for the sketches.

Circuit Elements - Power Dissipated

Given the circuit shown in the attachment find: values and power dissipated. (Please see attachment for complete question and diagram. Thanks)

Rankine Cycle - Net Power, Thermal Efficiency and Heat Transfer

Water is the working fluid in a vapor power cycle with reheat, superheat and reheat. Superheated steam enters the first turbine stage at 8 MPa, 480 C and expands to 0.7 MPa. It then is reheated to 480 C before entering the second turbine stage, where it expands to the condenser pressure of 8 KPa. The mass flow rate of steam e

Complex Power and Impedance

Question: An electrical load operates at 240 volts rms. The load absorbs an average power of 8 kW at a lagging power factor of 0.8. a) Calculate the complex power of the load. b) Calculate the impedance of the load. Please view attachment for multiple choice options.

Dissipations of Power in Lightbulbs

An incandescent lightbulb rated at 100 W will dissipate 100 W as heat and light when connected across a 110-V ideal voltage source. If three of these bulbs are connected in series across the same source, determine the power each bulb will dissipate.