Explore BrainMass

# Power Engineering

### Determine the percentage regulation of the transformer

Please show as much working as possible and comment where possible. An 11 kV to 415 V transformer has a rating of 100 kVA. The winding resistance and leakage reactance when referred to the secondary are 0.0142 Ohm and 0.0569 Ohm respectively. Determine the % regulation of the transformer at: (a) unity power factor (b) 0.

### 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

### Attenuation of received power with change in transmission frequency and distance between the antennas

How much would be the attenuation of the power received, if transmission frequency is tripled or if the distance between transmitting antenna and receiving antenna is tripled? a) 24 dB b) 20 dB c) 10 dB d) 16 dB

### 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.

### Calculate the open-circuit power absorbed from the supply by the transmission line.

Please show as much working as possible and comment where possible. The figure in attachment represents a high-voltage transmission line. With the receiving end on open-circuit, the relationships between the sending end voltage and current and the receiving end voltage are given by the equations in the attachment. Given t

### 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

### Audio Amplifier

Please analyze the attached schematic and include what each component does to the circuit. The circuit is already but how it is all functioning needs to be explained.

### 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?

### A factory's electrical load can be represented as three parallel admittances. To determine current, power factor, value of capacitor etc.

A factory's electrical load can be represented as three parallel admittances (see attachment). The values of the admittances are given in the table in polar form. (a) Determine (i) The current taken from the supply (ii) The overall power factor of the load (iii) The value of the capacitor required in parallel to the l

### 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

### Electrical wiring: Potentials of neutral and earth wires

Why is the neutral wire in housing circuits also at zero potential (in addition to earth wire which is also at zero potential)?

### 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.

### plot the real power delivered to the load

For the circuit attached, plot the real power (watts) delivered to the load as the load is varied as indicated. Please use Matlab and include equations used to plot. Please send source code. A)Plot power vs RL as RL = 800 to 1200 in steps of 20 with XL =1000. B)Plot power vs XL as XL = 800 to 1200 in steps of 20 with RL =

### 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

### Power Factor Improvement

An industrial user has a number of machine tools which are driven by three phase induction motors. during a particular shift, the power factor of the combined load can vary between 0.65(100 KVA load) and 0.81 (20 KVA) load. the user is contemplating using a capacitor bank to maintain the power factor at the point the 11KV supply

### Adjusting Resistance to Achieve Maximum Power Dissipation

Adjusting Resistance to achieve maximum power dissipation. See attached file for full problem description. Please answer number 7.4 only.

### Variation of Voltage Across a Capacitor

See attached file for full problem description. Please answer only question 1.2

### PLC Input and Power Supply

Attached are shown several external components and a 12 volt 8-point common input module for a PLC. The inputs on the input module share a single common terminal (COM). The inputs are bipolar. The sensor has a PNP output. It is powered by Vcc = 12V and its output transistor is ON when the sensor is ON. Wire the components to 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.

### ECL Gate

I would like a circuit diagram of the output stages of an ECL gate. Also stating the logic function

### 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

### Calculate the Complex power of a load

Calculate S, the Complex power of a load (In rectangular form), given the following data: Q = 2000 VAR PF = 0.9 leading See attached file for full problem description.

### Calculate complex power in an inductive circuit

Calculate S, complex power of a load (in rectangular form), given the following data: magnitude of S = 600 VA; Q = 450 VAR (inductive). See attached file for full problem description.