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

learn more… | top users | synonyms (1)

2
votes
2answers
51 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
55 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
vote
1answer
52 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
131 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
72 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
84 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
67 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
90 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
64 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
79 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?
1
vote
1answer
61 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 ...
3
votes
3answers
221 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 ...
-2
votes
1answer
114 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
261 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
381 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
77 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
142 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 ...
21
votes
4answers
1k 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
71 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
309 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
770 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
703 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 ...
1
vote
1answer
781 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 ...
5
votes
3answers
751 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
268 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
votes
1answer
190 views

Draw busbars in qelectrotech

In qelectrotech how can I draw a busbar?
2
votes
2answers
196 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 ...
2
votes
1answer
220 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
120 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
257 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
150 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 ...
2
votes
1answer
142 views

Transients and shielding in power transmission/distribution lines?

I've been lurking for some time on the board here - but hadn't had occasion to ask a question until now: Does anyone have experience with power distribution networks and their impacts on sensitive ...
28
votes
8answers
3k 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 ...
1
vote
1answer
353 views

IEC 60320 power cord rating

I am trying to determine what power cords I need to get to connect computer servers to 208v PDUs. I know the PDU has C13 receptacles I need a C14 to C13 power cord. However, I noticed there are ...
4
votes
2answers
204 views

What causes sub-second mains voltage outages?

Many times I observed a following electrical event: mains voltage will suddenly drop and then immediately restore. This causes lights to blink and computers to restart. I can't imaging what could ...
1
vote
2answers
3k views

What causes unequal phase-to-neutral voltages in three-phase distribution systems?

A four-wires cable runs into an apartment building to supply it with three-phase 380/220V alternating current. Each apartment is connected to one phase, different apartments are connected to different ...
12
votes
4answers
1k views

Why does electric arc in a switch prefer a curved path over a straight path?

Recently I found this video of a 500 kilovolts line being opened under load. When the switch contacts are pulled apart an electric arc predictably starts. While the contacts are close to each other ...
2
votes
3answers
642 views

How do utility companies treat voltage deviations in distribution networks?

I live in a region where nominal mains voltage is 220 volts and state standards permit deviations within 5 percent continuously and within 10 percent for short periods. So if I measure the voltage in ...
9
votes
7answers
5k views

What causes overvoltage in power grid?

In the region where I live there's a state standard that says that mains voltage deviation can be within 5 percent continuously and within 10 percent for short periods of time, so if the mains voltage ...
0
votes
1answer
196 views

Localized Star Network From Bulk Cap?

I was reading the Power Integrity article on Altera's website and came across the recommendation for the Bulk Capacitor (47uF to 100uF). I'm supposed to have one 47uF-100uF capacitor for every two ...
1
vote
1answer
174 views

how grid tie invertor works?

I read it somewhere that it should be a current source as grid is low impedance voltage source. ( whatever that means. ) I get the part where voltage is converted from DC to AC via Inverter. But what ...
4
votes
5answers
285 views

Is direct current really better for pumped-storage hydroelectricity facilities?

Currently the article equivalent to War of the Currents in Russian Wikipedia section says that direct current is beneficial to pumped-storage hydroelectricity plants and provides no reference to that ...
2
votes
1answer
170 views

What could be this “transient electric deviation”?

On August 7th, 2011 a lightning hit a transformer powering one of Amazon EC2 facilities in Dublin. The status report said Normally, upon dropping the utility power provided by the transformer, ...
3
votes
4answers
246 views

Why are power distribution systems so prone to massive faults?

Many region-wide blackouts (like this one or this one) are described as follows: some high-voltage equipment (like a generator or a transformer) fails and the grid gets overloaded and then protective ...
12
votes
4answers
3k views

How does earthing work when earth is dry?

Earthing is meant to provide reliable contact of an electric appliance to earth so that if there's an insulation fault current goes into earth instead of through a person's body. This requires ...
3
votes
3answers
2k views

Why would a power cable need copper wire shielding?

Today I witnessed burying 10 kilovolt power cable in the ground. I noted the cable mark and Googled it. The description is rather interesting. It's a single conductor cable - it takes three such ...
7
votes
3answers
4k views

How would an electric company detect wireless theft of electricity?

As legend goes it is maybe possible to steal electricity from power lines in a wireless way (also see this and this related questions). The legend continues that once someone does that he gets caught ...
2
votes
2answers
607 views

max amperage of WAGO 222-415 connector?

Here's a really nice multi-wire splicing connector: http://www.wago.us/news/5019.htm I'm using it for power distribution for a quadcopter: ...