Transmission Definition and 709 Threads

What is the meaning of the CESMM3 Ref in BOQ of Transmission & Distribution? In the Bill of Quantities of Some project of Electrical Transmission and Distribution I came across the CESMM3 Ref when I searched in the net I know that it is the " Civil Engineering Standard Method of...

Wireless electricity transmission works by passing alternating current through one coil to which another coil corresponds and thus is coupled. At least this is the way WiTricity explains it. They also say that it's very much like mechanical resonance and that's why it's more efficient over...

Hi guys, i would like to ask how do i increase my rpm using a gearbox (2,3,4 stages i don't mind) Input rpm 10 target output rpm 1500 and after that how can i calculate my torque?

Hello. Below I have a problem I can't quite understand to the full: http://www.israup.net/images/027d25c3acde86a09bcb9e1ed869560a.png http://www.israup.net/images/6757f5c30cbcfe051295b1b1e4614489.png And that is the suggested solution...

This question relates to rate constants of transition events. The transmission coefficient κ reduces the value of the rate constant compared to the transition state theory (TST) value. I understand κ to be defined as the probability that a reaction coordinate q will proceed to product given that...

Homework Statement A factory receives 120kW of power from a power station 20km away via transmission lines. If the resistance in the power lines is 0.5Ω/km, what is the power loss in the lines if the electricity is transmitted at 100kV (Approximate to a simple DC circuit). Homework Equations V...

My textbook had a section where a particle beam was going over a barrier where E > U and then right after that had a part about resonant transmission. It then went on to talk about Tunneling through a barrier when U > E. It didn't give a new resonant transmission equation and i assume the...

Homework Statement (a) Find the capacitance per unit length and find the inductance per unit length of a transmission wire above a infinite conducting plane. I used the image method (b) Show that EM waves can propagate, and find their speed and the characteristic impedance of the line...

Hello all this is my first post so i hope i can give you the relevant data in the correct format, also thank you for any assistance :) I am to find the OD of a hollow shaft when the shafts ID is 0.75 of the OD dimension, the shaft transmits 3MW at 200Rpm. The Shear stress max is 55 MN/m2 and...

Homework Statement Find the general solution for the current I(z,t) associated with the voltage V(z,t).Do this by substituting [1] into [2] and [3], integrate with respect to time, and then take the derivative with respect to z. Homework Equations V(z,t)= f+(t-z/vp) + f-(t+z/vp) [1]...

Homework Statement Attached is the problem. I am a little confused as to how I should be approaching this type of problem. If I Determine the input impedance for the first segment of transmission line and load impedance on the right, is that going to be in parallel with Z_L on the left? I am...

anyone can help me l want to make an electrical project wireless power transmission .can you please provide me some useful link where l can found circuit diagram and list of necessary equipment.

Hello i would like to know what is the different between 300km and 150km in transmission line.. thanks

Homework Statement Hey guys. I have a transmission line with a known characteristic impedance (50 Ω) of length L that is connected to an antenna that has a complex impedance of (50-j25)Ω. I am having extreme difficulty determining the minimum length (expressed in wavelengths) of line such...

Hi, I am having difficulty determining where the electric field comes from when an electromagnetic wave is emitted by an antenna. I know that the charges accelerate between an AC voltage but where does the electric part of the EM wave come from? In a normal wire there is no electric field from...

At the power-line frequency (50Hz), the wavelength of electromagnetic waves in free space is 6,000 km. Similarly, the phase velocity of voltage/current waves is about 4,000 km at this frequency. The question is, why do we bother about the wavelength at all at the power-line frequency, when the...

Hi, I've been coming to physicsoforums for years, I love the community! This might be my first post though. I am wondering what the impedance is of a transmission line with a matched stub on the end. The impedance of the line is 50 Ohms, and the impedance of the stub is 50 Ohms. Is the...

Hey guys, So I'm working on a project currently being built off of a cheap commercial Quad-copter (Syma X1) as it's base platform. Just as a little background I am trying to make it so that it is not controlled by a remote (that is pushing knobs and levers up and down to control it) but by EMG...

I am simulating an unshielded twisted wire pair of a communication network, Controller Area Network. Bus Speeds taken into consideration are 250/500/1000/2000 kbps. Depending on the physical dimensions of the wire and insulation dielectric constant, I have computed the R,L,C,G parameters...

Here are some figures from this article. Wiki: Electric Power Transmission Unless I made a mistake, that would be approximately 100W to 200W loss per foot. That's some 6 to 13 times as much as the percentage loss in the example above, but it doesn't tell me what is the line length or energy...

1. The Problem Statement An electron of effective mass m* = 0.2me and energy E = 0.1 eV hits a barrier of height 0.4 eV and width t = 5 nm. What is the probability of transmission through the barrier? Use the simplest estimate which is an exponential function. Homework Equations I think...

If you are a fresh graduate of BSc Electrical Engineering and you are asked to choose either Transmission & Distribution Department or Power Generation Department, which one will you choose? And why? Please your inputs will help me decide, so help me out. Airer

Hello, I want to build transmitters and receivers and I wonder if there is a tool kit which contains components building these circuits such as VCO, crystal oscillators, low value capacitors and inductors etc etc with various transistors. Also is there a transmitter that I can buy which allows...

Homework Statement A steady stream of 5 eV electrons impinges on a square well of depth 10 eV. The width of the well is 7.65 * 10^-11 m. What fraction of electrons are transmitted?Homework Equations The following equation for the transmission coefficient, T, is given: T = [1 + \frac{V_0 ^2...

WHat is the permissible maximum transmission ratio of a Spur gear pair? I read somewhere that it is 1:5. What wil happen if this is exceeded?

Hi, According to what I understood, when a terminal is connected to a line, it causes electrons to flow in one direction. And so for a single phase transmission line in parallel if connected to supply, then in one side electrons will be flowing in one direction and the same electrons will be...

For some reason I find it hard to comprehend that at the natural base level of existence (whatever that means), that the information-scape (all the stuff that is happening throughout space) is totally fragmented from each other, except of course for the "slow" transmission of information to...

two-port network transmission parameters?? Homework Statement Homework Equations t[A B]=[t11 t12] [C D]=[t21 t22] The Attempt at a Solution so, first thing i did was find the equivalent capacitance/inductance. C(eq)=-j0.5 and L(eq)=j0.5. using these values as I was confused by parametric...

This is not a homework, this is concerning reflection and transmission of electromagnetic wave ( plane wave) at a flat planar boundary between two media. But the work in question is pure vector calculus. I ultimately want to proof if ##\vec E_I=\hat y E_I## then ## \vec E_R## and ##\vec E_T##...

Problem Description: A hiker is reading a compass under an overhead transmission line that is 5.1m above the ground and carries a current of 807A in a horizontal direction from North to South. Assume the Earth's field is of the order 0.5*10^-4T. A) Determine the magnitude of the field produced...

These are questions for electrical engineers involved in electrical power transmission by overhead line and knowledgeable about current practices. - What catenary sag is normal, under normal conditions of weather and transmitted current? [obviously the answer will depend on the distance...

I am starting my 3rd year in September and I've decided to start thinking about research topics early. I'm quite interested in piezoelectricity along with it's discovered and perhaps undiscovered applications. This is my first idea; I have watched a lot of nature programs and I have seen that...

I am reading Griffiths p387. It is my understanding that \tilde E(\vec r,t)=\hat r E_0 e^{j(\omega t-kr)} Where ##\vec r =\hat x x+\hat y y+ \hat z z## is the positional vector from the origin to the observation point ( x,y,z). \Rightarrow\;\tilde E(\vec r,t)=\hat r E_0...

Suppose TEM wave in +z normal to a boundary on xy plane at z=0. We know E & H are tangential to the boundary. Let ##\vec E_i=\hat x E##, be the incident wave towards the boundary therefore incident H is ##\vec H_i =\hat z\times \hat x \frac {E_i}{η}=\hat y H##. I have a few questions...

I am working with an application where we have a magnet in close proximity to an antenna in the 20 - 25 GHz range. If there IS and affect of the magnet to the antenna's transmission, does the "near field" calculation apply (λ/2xpi)? If the antenna is out of the near field, is there no affect...

Electric Grid Question -- Elevated Transmission Lines Hi, Our teacher gave to us an homework which is if we carry transmission lines at 20000 m (20km) high from Earth face, what is this application's benefits and harms? Can anyone help me? Already thanks for your replies...

In the Midwest (Iowa, etc.), we get plenty of storms, mostly Winter, and power lines go down frequently. Someone is about to build a new high-power transmission line across my County (and too near my property!), and I can't figure out why it is not mandatory in the 21st Century that all...

Lets say we have a tunelling problem in the picture, where ##W_p## is a finite potential step: If particle is comming from the left a general solutions to the Schrödinger equations for sepparate intervals I, II and II are: \begin{align} \text{I:}& & \psi_1 &= \overbrace{A e^{i\mathcal L...

Hi, In very simple terms am I correct in thinking that bluetooth uses FHSS during signal transmission which involves changing of the carrier frequency at set intervals, essentially allowing the signal to change channels within the 2.4GHz band? Thanks

As I understand, electrons cannot be on the exact same level as another one in the universe. If we could move one electron in one placed and somehow monitor another ones reaction - would it be possible to instantly transmit data anywhere in the universe?

Hi -- I am trying to calculate the signal distance for a 2kw FM radio station broadcasting with a 157' antenna over average terrain. The FCC calculator requires field strength, and I don't have a clue what that would be. Can I roughly calculate broadcast distance using the known variables...

Lets say we have a potential step with regions 1 with zero potential ##W_p\!=\!0## (this is a free particle) and region 2 with potential ##W_p##. Wave functions in this case are: \begin{align} \psi_1&=Ae^{i\mathcal L x} + B e^{-i\mathcal L x} & \mathcal L &\equiv \sqrt{\frac{2mW}{\hbar^2}}\\...

Homework Statement You have been asked to develop a cross-country DC electrical transmission line to deliver 300MW of power to a town 200km away. This design is to only have a 2% loss (98% efficiency). If the line voltage is 600kV, what is the minimum diameter that the aluminum wire can be...

Does a DC transmission line for a given amount of power, do better at higher voltage? I know power is the product of the Voltage and current. The logic given to me by one of my peers was that I2R losses are less if the current is low. And so for a given power, it would imply V to be higher...

Hi when using the WKB approx, is there a general method to find these Refelction and Transmission coefficients, I have tried looking in books and on the net and I can't find a 'general' formula, they tend tjust to be quoted. I know that |T|^{2}+|R|^{2}=1 . And generally that T=...

So couple questions. My assumption is that a radio antenna gets bombarded with all frequencies at the same time. So there has to be a discriminating circuit with a radio to act as a frequency filter. Well could I do this naively with a low pass filter and a high pass filter together? In...

I use transfer matrix method. I try to plot the phase Φ(ω) versus frequency ω graph in the vicinity of a band gap. The transmission coefficient t(ω) is t(ω) = |t(ω)|*exp(i*Φ(ω)) from which I get the transmission phase Φ(ω) = atan(t_imaginary(ω)/t_real(ω)). Since I assume that -pi/2 ≦ Φ ≦...

Homework Statement A pulley 150 mm diameter is driven directly by an electric motor at 250 revs min-1. A V-belt is used to transmit power from this pulley to a second pulley 400 mm diameter against a load of 200 Nm. The distance between the centre of the pulleys is 600 mm, the included...

In transmission lines the the voltage is stepped up to a specified level thereby reducing current to ensure its transmission with minimal power loss. But we know that P=V*I so by increasing the voltage won't Powerloss gets increased?

Transmission line equation is of the form- Φ(x, t) = F(x − ct) + G(x + ct) where F(x-ct) is the forward traveling wave and G(x+ct) is the reverse traveling wave 'x' is the distance from the origin. Now my question is where does the origin lie? Usually in Transmission lines we assume...