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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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1answer
42 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
57 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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1answer
289 views

dq0 Transformation Interpretation

What is the physical interpretation of dq0 axis transformation in electrical machines and power systems? How does this transformation helps? Thanks
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0answers
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
15 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
5k views

What is this object found on transmission lines?

What are the components, circled in red in the figure, on this transmission line ?
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2answers
41 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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1answer
35 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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0answers
19 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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0answers
24 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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3answers
49k views

Why does a delta/wye transformer make 30 degrees phase shift ?

I'v heard that a delta/delta or Wye/Wye transformers do not make any phase shift. In delta/wye or wye/delta transformers, There is a 30 degrees phase shift between the primary and secondary coils. So, ...
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1answer
247 views

The critical clearing time (CCT) of a fault in DIgSILENT

How can I determine the critical clearing time (CCT) of a fault in DIgSILENT? How can I use DPL to determine the critical clearing time (CCT) of a fault in DIgSILENT?
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4answers
435 views

Power System Faults Problem

A sustained three-phase fault occurs in the power system shown in the figure (See Link). The current and voltage phasors during the fault (on a common reference), after the natural transients have ...
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2answers
88 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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1answer
157 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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0answers
27 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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1answer
125 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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3answers
146 views

Off grid LED solar lighting without batteries

I have 2 COB LEDs (12-14V DC, 50W, I think with 3,75 A in data sheet). I need to run them with a solar panel, it should only run when there is sunlight no batteries needed. Using a 270W panel (open ...
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0answers
44 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
114 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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2answers
69 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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0answers
49 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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6answers
1k views

Why am I getting shocked from “hot” line and touching “ground” (Earth)

So I live in an EU country and don't have Earth grounding for my house. Still I am getting shocked when touching "hot" line (220VAC) and standing on "ground" (Earth). How is this possible? From my ...
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0answers
20 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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0answers
13 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
83 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
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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2answers
140 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
477 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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1answer
108 views

Shorten the mini Christmas light strand

I need to shorten a 100 light strand of mini lights to just 18 lights. Based on the wiring, I believe the strand is engineered as two 50 light strands in parallel. The strand is rated for 120 V and ...
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2answers
37 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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1answer
1k views

Factors that limit maximum power transfer through transmission lines?

I have read that the maximum power transfer is limited by (1) Thermal Limit, (2) Voltage Regulation and (3) Transmission angle (Stability). Thermal limit is self-explanatory. Is voltage regulation ...
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4answers
101 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
27 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
33 views

Low voltage grid frequency with renewable feed-in

If a low voltage grid's consumption equals to that grids renewable energy production, does it mean the transformator basically does nothing, like an open circuit? Are grid-tied inverters (smart) ...
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1answer
76 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
94 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
81 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
78 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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8answers
9k views

Why do utility companies supply at a frequency of either 50/60 Hz?

It just struck me that Utility Companies world-wide supply domestic users at either 50/60Hz. It could have been selected to be 10 Hz, or 100 Hz ... whatever Was 50/60 chosen at random? Is there some ...
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1answer
234 views

How to predict the output of a solar panel depending upon weather conditions for real time hardware simulation?

I want to build a system for smart grid which can optimize the grid power, load and battery charging to reduce my costs for grid power. For the optimization problem, I must know the current date to ...
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1answer
141 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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4answers
16k views

How big current I can commutate using D-sub connectors?

The question Did someone knows what are the current capabilities of the standard D-sub (aka Cannon) connector. I want to use it for power source connection together with the signal. I need pretty ...
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0answers
31 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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0answers
51 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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8answers
12k views

Can a bird, previously at earth potential, get electrocuted by landing on a powerline at high-enough voltage due to the initial “equalization charge”?

At the voltage levels of typical overhead transmission lines in the US, a bird can land on one and be just fine (as long as it doesn't do something like spread its wings and touch a tree or something ...
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2answers
166 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 ...