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

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323 views

How do I, as a consumer, gain or lose when the utility company line voltage varies from rated value?

A little background; the line voltage supplied here in my part of India varies as a function of the load. At dusk, the measured value is as high as 248V. Household appliances are rated at either 220V, ...
2
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2answers
53 views

How exactly does the grid handle small deviations in power consumption?

I've heard many times that the grid electricity production and consumption must be balanced and imbalances lead to overvoltage or undervoltage. I've never seen an explanation of that phenomena from ...
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5answers
291 views

Which is harder on the power grid: a winter cold spell, or summer heat wave?

Just a wonder of mine, as I sit here listening to my heat pump struggle to maintain. For the Q, assume the North East USA. I think Summer heat waves are more difficult for the grid due to A/C load ...
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0answers
28 views

What's the typical harmonic distortion on the secondary side of a distribution substation?

What's the typical harmonic distortion and waveform found at the low-voltage side of an urban substation (I.e: the aggregate of appliances and secondary distribution system impedance)?. If you can ...
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1answer
54 views

Is it a problem in a single-phase system, if a generator shares neutral with the grid?

I'm planning to use a generator to bridge longer power outages. Both the house and the generator are single-phase. If the main breaker is off, it will only disconnect the phase, the neutral will still ...
0
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1answer
41 views

Fault on a tri-phasic circuit

I work on a industry as an intern and I'm having a trouble. Clearly there's a fault on the net, but I can't figure out which type it is since I'm having strange readings from a basic multimeter. I'm ...
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0answers
11 views

Easy power and graphs

I'm using EasyPower demo software to analyze a distribution system, but compared to ATPDraw it does not show waveform graphs, like voltage, to allow seeing transient behavior. Is there any way to see ...
0
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0answers
14 views

How can I enter per-unit values on ATPDraw software?

I'm studying the AOV (Area of Vulnerability) of certain distribution system with distributed generation and I'm using ATPDraw software. As the real system is so big and its data is given in p.u. ...
2
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1answer
93 views

How are power flows between multiple power systems (tie-line flows) determined?

In Europe, for example, there are multiple transmission system operators (TSOs), which are responsible for their own region of the grid. These TSOs must exchange power to ensure reliable operation of ...
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0answers
74 views

What is a Thyristor Switched Series Capacitor (TSSC)?

I'm struggling to understand the physical difference between the Thyristor Switched Series Capacitor (TSSC) and the Thyristor Controlled Series Capacitor (TCSC). From this book, I understand that a ...
3
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2answers
137 views

Why is it desirable to inject reactive power into a transmission system?

This website explains the basics of FACTS technologies and how they can be used to exchange active and reactive power with the transmission system, namely: SSSCs - can exchange active and reactive ...
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1answer
87 views

Comparison between AC and DC power flow analyses

Consider a power flow problem. Injected real and reactive power at a bus are functions of voltage magnitudes and voltage angles and are given by \begin{align*} P_i = ...
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2answers
135 views

Zero resistance transmission lines?

I am using the IEEE 14 bus test system for a simulation and was wondering why some of the resistances of lines are set to zero, e.g. see lines (4,7), (4,9), (5,6) below (only part of the full data is ...
2
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1answer
146 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 ...
2
votes
2answers
105 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 ...
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1answer
84 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 ...
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2answers
85 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
87 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
72 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
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3answers
267 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
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1answer
282 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
362 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 ...
3
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1answer
153 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
166 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
120 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 ...
9
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2answers
2k 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
4k 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 ...
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3answers
274 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 ...
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3answers
115 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 ...
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2answers
475 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
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2answers
765 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
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3answers
1k 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. ...
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1answer
86 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 ...
3
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1answer
776 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
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1answer
169 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 ...
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2answers
129 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
295 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
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1answer
1k 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
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1answer
139 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
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1answer
227 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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1answer
78 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 ...
9
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5answers
2k views

What does this symbol indicate (line with brackets)?

I'm modelling a power system, and encountered a few symbols I have never seen before in a single line diagram. I believe the first one is a switch with three possible position. Closed, open and ...
4
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3answers
3k 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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1answer
310 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?
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3answers
1k 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 ...
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3answers
2k 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
111 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 ...
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2answers
192 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 ...
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4answers
3k 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
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2answers
116 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 ...