Questions tagged [power-engineering]

Power electrical engineering. Includes industrial electrical engineering (i.e. motors, switchboards), transmission and distribution (poles, wires, transformers, grids) and generation.

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2answers
36 views

Instantaneous and active power in an ideal switch powered by real source and squared wave

This is a somewhat theoretical question, but one that has some impact on power theory. The circuit in the figure is composed of a real DC source (with non-negligible internal resistance) and feeds a ...
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1answer
30 views

Quantify Grid Stiffness

Being the stiffness of the grid its capability of maintaining the voltage constant despite small variations on load. Whereas, a weak grid would be easily affected by load variation and the voltage ...
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20 views

Transmission Line Impedance 3 phase

I have the following question that I can't seem to figure out. The question ask to solve for the impedance of a 3ph transmission line. I've found the De (distance relative distance) and XL using the ...
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1answer
57 views

How can I compute the power flow for a network with transformers (as in the WECC 9 network)?

I'm trying to solve the power flow for the WECC-9 bus reported below: all generators (1,2 and 3) are behind a transformer, which has a Voltage converter ratio (e.g. 18/230) and a reactance(?), which ...
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2answers
84 views

How does the arc extinguisher work in a miniature circuit breaker?

In a miniature circuit breaker, as shown below, the distance between open contacts is much less than the distance between metal bars in the arc extinguisher part (the gap gets progressively longer ...
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27 views

Grid Tie Inverter Anti islanding

I was wondering about anti islanding design. Using grid tie inverters is usually the best choice when not investing in batteries, but suppose you have batteries and want the confort of grid tie AND ...
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0answers
51 views

What will happen if the prime mover driving synchronous machine is accidentally disconnected?

What happens to a synchronous machine connected to an infinite grid, acting as a generator, when its prime mover fails i.e. when mechanical input at the shaft reduces to 0? I'm assuming that the ...
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27 views

Power management switch for Low-Power Application

In my low-power application I have a MCU waiting for an interrupt to wake up. (see picture) There are two sensor ICs (IC1, IC2) which consume very little and wake up the MCU via the interrupts. After ...
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25 views

Why the Photovoltaic(PV) variations may cause shutdown in the main grid

If we assumed that PV generator is connected to the main grid, as the PV depends on solar irradiance it is considered to be a variable source. If the PV source can cause variations that could be ...
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42 views

Can we use the Halbach array configuration in an electromagnet?

I tried asking this question in several forums but didn't find any answers as i expected. It's very hard to find information about halbach array in google, especially in the electromagnetic field. We ...
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5answers
13k views

What is the speed of “electricity”?

In a distribution grid, what is the speed of energy signal Is it strictly the same? And how is synchronisation achieved? Is an electric grid essentially an orchestra where everyone is the chief ...
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3answers
507 views

Producers consumers balance in the grid

In a large distribution grid, it is said that consumers and producers must be in balance; what that means physically, in correct (not simplistic) mathematical formulation, is not clear: perfect ...
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1answer
38 views

Constant current and constant voltage control of inverter

Most of inverters in the grid are based on constant current control where inner current control loop tries to limit the current. Hence acting as a constant current source. I was wondering how control ...
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1answer
31 views

IEEE test system accuracy and transmission line connections

In practice, do transmission lines ever directly connect two electrical generators to each other? Or is it more common for two generators to be connected indirectly through a substation? In the IEEE ...
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1answer
49 views

linear model of a power load at the end of a transmission line

I am working on a controller that will regulate the voltage at the end of a transmission line into a variable load. I am able to ignore the inductive effects of the line at the frequencies of interst, ...
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3answers
60 views

Real Power or Reactive Power in Superconducting Motors?

My circuits class is teaching that in AC power, there are two kinds of loads. One is a resistive load, with absorbs power at all times. The other is a reactive load, which absorbs zero average power. ...
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58 views

How is AC load distributed across on-site generation and the utility?

I’m trying to understand the physics behind AC load distribution when distributed on-site generation is installed and the load is also connected to the grid. In the diagram below, I have a building ...
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0answers
28 views

How is voltage induced in Yd transformer without neutral connection sinusoidal?

Thia is regarding bank of 3 single-phase transformers having star connected primary with isolated neutral and delta connected secondary. I know that for bank of 3 single phase transformer core flux ...
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1answer
37 views

Controlling multiple floating power supplies from a single point

I have assembled a power supply from five HP dps-750rb common slot power supplies. All five units are in series. I have the first grounded electrically and have the other four units modified and ...
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2answers
44 views

AD8318 Maximum Input Voltage

let's consider AD8318, a chip which contains a logarithmic amplifier, often used for power measurements. I have read its datasheet and there is a thing that I do not understand: no maximum input RF ...
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24 views

Peak Current in a transmission line

Let's consider a transmission line (which drives a generic load ZL) connected to an AC voltage source. If we know that the peak voltage of the source is equal to Vp, how can we evaluate the peak ...
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25 views

Impact of Interconnection of One Energy Generating Plant At Another Generator Plant's Generator Bus Bar(PV Bus Bar)

As the scheme attached below, we're interconnecting 5.5 MW of generated power of upstream project(Around 2 km Away from the Interconnecting Switchyard) to the Generator Bus Bar(PV Bus Bar) on 11 kV ...
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2answers
191 views

What does “reconductor” or “reconductoring” refer to?

This is a term that I seem to remember hearing in reference to electric transmission. I'm pretty sure it has something to do with upgrading a set of transmission lines to carry more current, but I'm ...
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28 views

Isolation voltage of a flyback transformer

How to calculate the isolation voltage of a planar flyback transformer? Or if there are any standards about it? I am designing a planar flyback transformer that need an isolation voltage of 1000V, ...
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48 views

Power Distribution Blocks for DC voltage?

So, I'm pretending to use a somewhat uncommon component for my generator system. With an alternator, I will generate 24 V DC and a maximum of 100 A. My question is, can I use a power distribution ...
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2answers
124 views

Physical Limits on HVDC Voltage [closed]

Higher Voltage minimizes I^2*R losses in power lines - we have power lines up to 1 megavolt, and presumably going any higher in terms of voltage doesn't save you too much power. But say we do ...
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95 views

Explain three phase motor running reverse and forward direction [closed]

Determine three phase motor running reverse and forward direction stops just one bushbotton
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56 views

Power Distribution for multiple 5V consumers

I'm a newby in the field of Electrical Engineering (only basic knowledge from school). Nevertheless, I need to power up to 10 Raspberry Pis (5V, 2A) with Dupont Connectors and AWG24 cables over GPIO ...
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5answers
3k views

Why/when is AC-DC-AC conversion superior to direct AC-AC conversion?

I am currently studying wind power and the power electronics used for it. In wind power a generator is driven by wind, thus the resulting power is of widely varying frequency and amplitude. The power ...
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1answer
179 views

What are these parallel connected lines meant for?

During my walk today, I noticed these small parallel connected lines. What purpose do they serve?
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23 views

How the directional element in the distance relay blocks the reverse power flow?

Following is the figure for directional element of distance relay. The trip region is also in the second quadrant. How it will restrain from operating if the fault impedance is as indicated by F (in ...
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25 views

Surge Impedance loading

I am working on my Power system exercise-related to surge impendence loading. I understood that surge impedance loading of a transmission line is the MW loading(unity power factor)of a transmission ...
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2answers
153 views

Stacking M.O.T. to create an E-E core

I just came across this site looking for answers on some questions I have concerning microwave oven transformers (M.O.T.). I am currently going into my third year as an E.E. student and I am trying to ...
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1answer
141 views

What is the purpose of these PTs?

What is the purpose of these PTs installed on the two coupled busbars? And we have whole panels in the HV room for these PTs. Kindly explain. (Photo attached)
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1answer
54 views

Can the power transfer ranges of wireless charging devices be extended to across a room? [closed]

Wireless charging devices charge devices by creating a magnetic field that induces an electric field in the device (like transformers), but its strength is inversely proportional to distance squared. ...
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3answers
236 views

Different colors for Power Transmission Towers

I have observed that some areas have some power transmission towers painted in Red and white colors. But, more often, transmission towers are unpainted. An illustration of what I mean by this, enter ...
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4answers
487 views

Is there a minimum amount of electricity that can be fed back into the grid? [closed]

This is not fully related to electrical engineering, but I have been reading lately about Feed-in-Tariffs and solar energy production and I cannot find any information on the amount of energy that can ...
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2answers
42 views

Transistors' Scattering Parameters

I have some doubts about the Scattering Matrix of a transistor seen as a 3 port devices. Precisely, I read (for instance here) that we do not have 9 independent S parameters since there is this ...
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4answers
110 views

Volume risk in an electricity market

I have been reading lately about electricity markets and I have stumbled upon the term "volume risk". Volume risk is often used to denote the phenomenon whereby electricity market participants ...
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0answers
38 views

How to model P, V variations in PV buses in a load flow problem?

I'm trying to use the DC power flow results as a base, and modify it to approximate AC power flow results more accurately. So far, I have been able to do that in a few simple test cases from Matpower, ...
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1answer
80 views

signal propagates in bending transmission line (unequal length between signal path and return path)

Suppose I have a square wave signal generated from a signal generator and its outputs are connected to the two terminals of a paired PCB traces (left side of the picture below). The other end of the ...
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2answers
101 views

What causes power losses in transmission lines?

From my understanding there are two causes for power losses in transmission lines: Losses due to resistance: \$ R = \frac{\rho l}{A} \$, where \$\rho\$ is the resistivity, \$A=\pi r^2\$ and \$ l \$ ...
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1answer
75 views

What will be Resistance for maximum Power transfer from network A to network B?

simulate this circuit – Schematic created using CircuitLab Can we apply Maximum Power transfer theorem if we are given two networks both with voltage sources. In solution it was said that for ...
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1answer
85 views

Does using HVDC for distance transmission make theft of electricity easier to detect?

In particular, if you were going to try to steal power from HDVC transmission lines you'd need one cable attached to current going in 1 direction and the other attached to current flowing in the ...
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1answer
116 views

can someone help with this question with capacitors

Please I need help solving this one, the book is Thomas Floyd 3rd edition Electric circuit fundamentals. The final answer is supposed to be \$ \text{0.0052 } \mu F\$ The ac source frequency \$f=...
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2answers
82 views

Harmonics in power system [closed]

I have seen in some text books that power converters produce harmonics in power systems. How do power converters inject harmonics in a power system?
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1answer
201 views

Instantaneous power

A sinusoidal voltage source v =10V sin(ωt) is connected across a 1k resistor. Make a sketch of p(t), the instantaneous power supplied by the source. Determine the average power supplied by the ...
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0answers
33 views

What does 'Rectifier Loading Effect and Loading Factor' mean

I came across the terms 'Rectifier Loading Effect' and 'Rectifier Loading Factor' when reading IEEE Std 421.5-2005 Recommended Model for Power Stability Studies, mentioned in those ACxA models. What ...
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53 views

How to have Wye-connected Potential Transformers(PTs) and Neutral Ground Resistor short circuit detection at my ground fault protection relay?

Detecting if the Neutral Ground Resistor (NGR) is shorted is something that must be checked at the Ground Fault Protecting Relay. The typical way to do this is to inject a DC component and to measure ...
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2answers
230 views

What is the direction of negative reactive power

In a R+1/(jwC) load (AC)voltage lags current with θ degrees. Reactive power Q is negative because sin(θ) is negative. My question is how can a capacitive load deliver power to the source wich is ...