Tagged Questions

Utility-scale power distribution, i.e. electricity grids, substations, overhead lines.

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0answers
21 views

Convert transformer resistance data from Watts to Ohm

Short version: How can I convert transformer resistance values from Watts to Ohms? Long version: In PSS/E, transformer resistance can be entered as either per unit values (system base or transformer ...
1
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2answers
56 views

What do the terms “cuts” and “jumpers” mean?

specifically, with respect to the electrical grid. Here's an excerpt from something that I'm reading that I don't understand: Switching operations, including applying cuts and jumpers, can be ...
1
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1answer
70 views

How to step-down voltage without a transformer?

Say I am running a line from transformer to a distribution panel that doesn't quite need 240V but less. How do you go about creating the required voltage drop? P.S: I may have phrased the question ...
-1
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2answers
76 views

Electrical measurements of Chicago substation from where can I get it? [closed]

I am doing a project on electrical load prediction using machine learning. Machine learning involves creating models based on past data. For creating these models where can I get data regarding ...
1
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2answers
76 views

Power Conducting Stepper Motor?

I have a question that I'm not really sure how to ask, so here goes: So I know there's such a thing as a power conducting slip ring motor, which I assume allows the passthrough of power through the ...
0
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1answer
66 views

Prevent EPROM powering from IO pin

I consider using a cheap Microchip 3-pin EPROM with single bidirectional data line as ID storage on various daughter boards. Since I don't want to waste daughter board connector pins on a device ...
2
votes
3answers
150 views

Why is the earth a viable return path for power distribution?

I'm having trouble understanding why the earth is a viable fault path for electricity brought into my home. Isn't there really high resistance? I mean, it's dirt? Also, let's say I connect the hot ...
1
vote
1answer
171 views

Why are the ground and neutral bonded in my panel?

I took a look inside my panel today and saw a big green wire connected to the neutral bus bar. Why are these two bonded together? Why not just send the neutral back where it came from? Where does the ...
0
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3answers
169 views

With a transformer center tap, why are the two resulting circuits out of phase by 180*?

I'm trying to understand how the power in my home works, and the part I'm having trouble with specifically is why in the step-down service transformer, the resulting out-of-phase 120V "hot" lines are ...
2
votes
1answer
98 views

Why / how does reactive power help improve voltage quality?

This question is related to my previous question that Olin provided a great answer to. Note that this question is about transmission and distribution systems, not electronics. I believe the claims ...
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1answer
115 views

Bus bar calculation

I am trying to learn bus bar calculations steps . can someone help me how to get started for DC/AC bus bar calculation. how to get started?? what are the parameter need to be considered. 3.when skin ...
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0answers
83 views

Calculating Voltages in phases when a neutral fails

In the above star-connected three phase circuit the neutral is floating. I need to find the voltage across each load and which voltages are higher than 240 (Assuming the Line-to-line voltages are ...
8
votes
2answers
612 views

Why does reactive power affect voltage?

Why does reactive power influence the voltage? Suppose you have a (weak) power system with a large reactive load. If you suddenly disconnect the load, you would experience a peak in the voltage. Is ...
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6answers
2k views

What happens to excess energy fed into the power grid?

The closest question to this is Linear useage of excess power generation. I'm no engineer so I may not be able to phrase this correctly and would appreciate an answer which assumes minimal ...
1
vote
3answers
155 views

Ensuring that the a circuit breaker in a secondary elec. distribution board will go off before a circuit breaker in the main board

I want to create a small portable single-phase secondary electrical distribution board to safely power up some lights in my back yard. The board will be powered from a wall socket, and will contain ...
-2
votes
3answers
107 views

3-phase electricity availability in USA [closed]

I want to ask about availability of 3-phase electricity in USA. I live in Europe, in small town (population: 3000). We have 3-phase electricity available everywhere, even in small villages near my ...
1
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2answers
241 views

Why are twisted pair cables used in electric power distribution systems?

I'm an Electrical Engineer, and understand how twisted pair wires can reduce noise susceptibility in the presence of magnetic fields. I recently noticed the power company replacing a long stretch ...
2
votes
2answers
484 views

Short circuit current through multi-winding transformer

I have a (radial) system with several multi-winding transformers, for instance one 24 MVA 7-winding transformer from 11 kV to 1.92 kV. I want to calculate what the short circuit current will be on ...
2
votes
2answers
455 views

Switchgear vs. power distribution center (PDC) vs. motor control center (MCC) - what's the difference?

Here's what I've observed so far: All three contain circuit breakers. All three supply power to motors, although switchgear and PDC-fed motors are obviously higher-voltage, larger motors. ...
1
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1answer
72 views

Photo-voltaic power source connecting to a grid: can I feed the greed? [closed]

Let's say I have a PV power source generating 50/60 Hz 230VAC power. I could connect this power directly to the grid assuming that I will consume all generated power for my own needs or, if the power ...
2
votes
1answer
438 views

What happens to a transformer if the supply side is shorted?

Suppose I have an industrial plant, where a switchboard is fed through a transformer. The switchboard have only "passive" loads, i.e. they don't contribute with short circuit currents. If there is a ...
2
votes
1answer
141 views

Disconnectors Symbol in Single Line Diagrams (SLD)

where should the moving part of a disconnector be located when breaking gets applied, on the energized side or on the disconnected side? Is there any standard?? Suppose a non ring, simple grid and ...
1
vote
2answers
113 views

Why does power go both to and from a power station?

It is common practice that wires in power lines send power both to and from a power station. Suppose that, instead of forming a closed circuit between a substation and a consumer, both the substation ...
2
votes
1answer
196 views

Modelling of dynamic behavior of a weak power grid?

I'm modelling the dynamic behavior of a weak power grid. I know the voltage level and short circuit capacity, and that's about it. Short circuit max = 400A, 3-P Voltage level = 66000 V My problem ...
3
votes
1answer
600 views

What is the percent impedance of a typical residential power line transformer?

Power transformers are rated by percent impedance. A 5% transformer, when loaded to full spec secondary current, will show a ~5% deviation from nominal output voltage. What is the percent impedance ...
2
votes
1answer
108 views

Parallel Transmission Lines

I am studying the RTS 96 test system for a power system simulation in Matlab. I have noticed that under the Branch Data file, there are some buses which have two lines connecting them. For example ...
2
votes
1answer
136 views

What is a SRF? (This is used in AC power distribution system with isolation transformer)

Following image shows a block diagram of a AC power system. What is that SRF equipment comes with the isolation transformer? What SRF means and what it does?
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vote
1answer
67 views

How power supply companies can measure the time of blackout in households? [closed]

Literally the event when the household does not get and electricity in case of cable snap or some accident on local station. Imagine coming home, turning the switch on, but getting no light in the ...
4
votes
3answers
2k views

How is transition from three-phase distribution without neutral to three-phase consumption with neutral achieved?

A typical distribution grid supplies 6 or 10 kilovolts AC to a substation near the consumers. This is typically done with a three-phase line without neutral - just three wires going in parallel. Then ...
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votes
1answer
225 views

Effect of corona on overhead transmission line [closed]

In text book, it has been said that corona reduces the effects of transients produced by surges. But, how does corona reduce the transient effect?
5
votes
3answers
790 views

How are multiple power sources synchronized in a grid that uses a distribution ring?

A large distribution grid can work like this. There're several power station each outputting 50 Hz AC. Each power station feeds energy into a substation next to it which raises the voltage and then ...
0
votes
3answers
1k 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 ...
2
votes
1answer
97 views

A confusion about radial schemes in power distribution

My lecture notes about distribution systems/radial schemes say the following: •In this scheme, feeders radiate from a substation in all directions and feed distributors at one end only. • SA is the ...
5
votes
2answers
170 views

mains frequency accuracy worldwide

I like to build a device that needs long term time stability. In germany, one of the best simple clocks use the mains power frequency to obtain a time measure. While the frequency is allowed to change ...
22
votes
4answers
2k views

How do transposition towers in transmission lines work?

There're such things as transposition towers in power distribution powerlines. The idea is that for example you have three conductors running in parallel at the same height and the leftmost of them is ...
0
votes
2answers
99 views

Barrier strip for power distribution

I'm working on a project where I need to supply power to multiple strings of LEDs, operating at 12VDC, with a max current draw of 20mA per string. What I'm looking for a quick and easy way to connect ...
3
votes
2answers
474 views

Can power theft on a large scale be stopped

Reading this article, I started wondering if there is any way to stop people stealing electricity from a power grid. Let me clarify, the only techniques I have seen (and can think of) is either to ...
4
votes
2answers
2k views

Guessing power line voltage from the number of disc insulator

Is there a good way to guess the power line voltage based on the number of insulator discs that attach the line to the transmission tower? Wikipedia seems to suggest that there is a "Typical number ...
28
votes
2answers
772 views

If we could start our electrical grid from scratch with today's technology, which would be the most efficient choice? AC or DC?

Lately, I’ve been reading about the many advantages of HVDC transmission systems for long distance transmission, undersea links, and others. The historical reason of why AC was picked over DC was ...
2
votes
2answers
1k views

3-phase power calculation when phase to phase voltages are different

I have a 3-phase power supply rated at 230VAC per phase. However, the phase to phase voltages are not equal. Suppose \$V_{RY}\$, \$V_{YB}\$ and \$V_{BR}\$ be the three phase-to-phase voltages between ...
6
votes
3answers
2k views

Why are the power transmission/distribution systems AC and not DC?

Is there a good reason why we are not in the process of completely converting our electrical transmission system to DC? The main reason for using AC on the grid (no offense Tesla, I love you man) was ...
4
votes
4answers
279 views

Is it practically possible to transfer electrical power around the World by wires?

Assume that we installed plenty of solar cells in all continents; mainly in Asia, Africa and America. Can we transfer the electrical power harvested from them around the World through wires? So that ...
0
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1answer
242 views

Draw busbars in qelectrotech

In qelectrotech how can I draw a busbar?
2
votes
2answers
223 views

Can current be drawn from ground in a SWER transmission setup?

I am almost certain that this is a ridiculous question, but cannot figure out why this scenario would not work. From what I understand, current from the electrical station is distributed to houses ...
6
votes
2answers
333 views

Why the delay between transformer failure and power outage?

A friend witnessed the explosion of the 14th street substation. I believe these transformers, about 1 city block in extent, delivered power to most of lower Manhattan. I am guessing the flood water ...
0
votes
1answer
49 views

Routing Current to Many Individual Channels [duplicate]

Possible Duplicate: How to implement an isolated connection matrix I need to put current on up to 30 lines; one at a time. What kind of electronics solutions are there to this kind of ...
1
vote
2answers
121 views

What is the name of a device that would send input current out to my home and maybe upstream from a power device?

Please edit this since I'm too ignorant of electronics and electrical equipment to explain this well. I'm looking for a device that I can create that would take AC or DC current from a power source ...
3
votes
2answers
285 views

Connections in load flow analysis

I have a very theoretical doubt. I'm trying to fully understand the load flow analysis and its application. So I have a network with about 300 nodes (AC transmission network). Inside every node I have ...
-1
votes
1answer
164 views

Power Grid in depth explanation [closed]

I am looking for links, books, papers, documents or any other reference type that allows me to get a very in depth overview of the power transmission and distribution network (preferably of the UK). ...
5
votes
3answers
2k views

How does DC transmission require several times less wire than AC?

In this YouTube video (scrolled to 5:55) there's a claim that replacing an AC high voltage transmission line with a high voltage DC transmission line allows for having seven times fewer powerlines ...