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
97 views

Grid is capacitive in the evening

what does this term mean? "the grid in the evening is capacitive"? I work at a company and we are working on integrating a battery storage system on a utility scale for peak shaving of solar. When we ...
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1answer
71 views

One-third neutral and full neutral

This is my first question here; if its not good enough, please let me know. Thanks For underground cables, we can choose "concentric neutral cable" or "tape shielded cable". For the first ...
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0answers
58 views

What is flashover in transmission lines?

I came across the following sentence in my electronic design book: "The power-handling ability of a transmission line is limited by flashover." There is not explanation in the book and I can't seem ...
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5answers
4k views

Why don't we use neutral wire for to ground devices and earth wire for closing the circuit?

I know that the neutral point of a distribution transformer is connected to the grounding (earthing) wire so I thing they are the same. Can I use the neutral wire for protection purpose and connect ...
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0answers
18 views

Black body heat to current conversion

I have learnt about Seebeck effect and peltier effect in college physics, but it was more of theory than hands on numbers and practicals. Now is there a commercial or DIY module that can produce ...
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1answer
67 views

kilowatt meter is using a proportional voltage x amps to create watts problems

So if a kilowatt meter is using a proportional voltage x amps to create watts used then in a situation where. 1. A pump motor using lets say 220v single ph is running while or starts running during a ...
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1answer
60 views

Twin wire neutral

I work in the power distribution industry and recently came across a 3-phase LV circuit with "twin-wired neutral" (i.e. two neutral cables inter-winded, therefore five cables total). What would be the ...
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2answers
44 views

Can an audio receiver with a 130v-rated switching power supply be modified to be used without a power transformer?

I have a Harman Kardon AVR, imported from the US, which uses an SMPS (130v) that I will use in Asia. Is there a way to modify the component inside the Power supply so that I can use it without a ...
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0answers
33 views

What is Virtual Array Antenna?

What is virtual array antenna (VAA)? I have searched it everywhere but i was unable to find direct answer to this question. I know this concept was built from phased array antenna. Please explain ...
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6answers
438 views

Why do we need to install a power transformer for each high building?

I live in area where many high buildings are being built. Each building is more than 10 floors. A special room is made next to the main entrance or the garage. The room is designed for installing a ...
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1answer
87 views

A question about the sound of corona discharge

In my collage, We were doing an experiment of the air's Breakdown voltage . At the end of the experiment we were listening to the sound of corona (electric partial discharge). The power supply has the ...
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1answer
94 views

Electrical schematics component ID's

Is there a list of standard ID codes used for components on a schematic drawing that anyone can point to? e.g. K = Contactor S = Switch Y = Solenoid X = Terminal strip etc. Any list would be ...
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1answer
32 views

Appox. the Impedance of Single Phase Pole Transformers using only Nameplate Ratings?

I know the following of one pole transformer (don't have access to the nameplate): 333KVA, Z = 5.75 % 25kV/12kV Given another transformer, I don't know Z, but know it's rating and voltage ...
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2answers
95 views

How to calculate instantaneous active power from sampled values of voltage and current.?

I have sampled values of voltage (phase to ground) and current (line current). I can calculate instantaneous apparent power using: $$ P(i) = V_1(i)I_1(i) +V_2(i)I_2(i) +V_3(i)I_3(i), i\in [1,n]$$ ...
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1answer
39 views

Why am I getting different Voltage Losses?

The step-down transformer has a ratio of 10:1 $$P_{globe}=V_{globe}\cdot I_{globe}$$ $$P_{globe}=V_{globe}\cdot I_{globe}=\left( 2 \right)\cdot I_{globe}=4\ \mbox{W}$$ $$I_{globe}=2\; ...
3
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2answers
248 views

How to synchronize a generator on the electrical grid?

I've read many articles about paralleling two portable generators or synchronizing a power generator on the electrical grid. I have the theoretical background about that topic and I know the four ...
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1answer
80 views

Phasor Measurement Unit (PMU) vs Synchro-check Relay

What is the difference between a Phasor Measurement Unit (PMU) and a Synchro-check relay? I need to know if Synchro-check relay can be used as replacement for PMU in a Synchrophasor data system. We ...
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1answer
78 views

On load tap changer controller switching

A 20/25 MVA transformer has an On load tap changer (oltc). Here a HMK7 Controller is used to control the motor drive of oltc. Which seems like There are two buttons 1-N & N-1. Red seven segments ...
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2answers
71 views

What is the effect of heavy loads on the electrical grid?

When our neighbors turns on a motor, a bulb in our home turns off for a very very short time and then it turns on again. It is something like a quick flash but a man eye can notice it. Would you tell ...
2
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1answer
95 views

Deformation of Heated Transmission Cable in a Conduit

Say I have 2000' feet of single phase XLPE cable with a 4" outer diameter in a 6" conduit, for simplicity, assume the conduit's inner diameter is 6". Also assume the cable is pinned at both ends and ...
6
votes
3answers
335 views

Capacitor exploding in a paper plant

Two years ago I was in an internship in a paper plant in the Superintendence of Electrocontrol, in the area of maintenance of electrical equipment. Well, they had a problem regarding some capacitor ...
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2answers
319 views

What is the zero-sequence equivalent of a YNy0 transformer?

The zero sequence equivalent network of a YNy0 transformer with grounded primary is shown below (source). It looks like there is no connection between the primary and secondary side of the ...
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1answer
250 views

Difference between disconnector, circuit breaker and load break switch?

There are various types of devices available for carrying out the switching and tasks. I have a question about the differences between disconnectors, circuit breakers and load break switches ...
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1answer
149 views

What are these coils on transmission lines?

What are these coils? This was asked by doetoe in this physics.stackexchange Question Where I saw them (maybe six or eight pairs) they came in pairs, always on the same two lines, and they were ...
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0answers
63 views

What is the ramp rate of a battery used on the grid?

For grid applications, I am looking for typical ramp rate of Li-ion batteries. I am specifically interested in batteries used for frequency management. So suppose I have a 1MW grid connected battery ...
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3answers
56 views

Given thermal capability of a transformer, how to best estimate the voltage regulation?

I'm working with a system that has 3 2MVA transformers for which there is an existing estimate of the peak load and the power factor. The xfmrs appear to have a greater thermal capability than the ...
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1answer
73 views

Grid changeover switching

I am designing a changeover circuit that will switch the power of attached appliances between two electricity providers. The two AC mains are of 220V RMS voltage and 50Hz frequency sine waves. The two ...
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1answer
96 views

What is the cause of voltage phase shift in a power system?

What element(s) cause the phasor voltage to shift in a power system? Why does the voltage phase angle increase with distance in a power grid?
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1answer
2k 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
137 views

what is shunt charging in power systems?

I am currently working with Power World Simulator. When inserting transmission lines, there is a parameter called shunt charging. What is this and what effect does it have on power loss in the line?
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1answer
80 views

Is my current transformer rated for 11kV Tranmission line?

I'm using a current transformer to measure current on HV transmission lines. Except i'm finding it difficult to find a split core CT that will be rated for 11kV. My CT that i'm looking at is the ...
1
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1answer
71 views

Modelling grounding reactor as transformer

First: This is not a question about electronics, it's about large (three-phase) power systems where the components have ratings in kV and MVA. I'm mainly interested in symmetrical components, and how ...
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0answers
85 views

Physical Sensation When Driving by Electric Utility Fault/Arc?

While driving home from work this afternoon during somewhat-cloudy daylight, I suddenly noticed a bright bluish glow on nearby objects, heard a loud hum that sounded like it had 60/120ish Hz ...
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10answers
8k views

Why three-phase power? Why not a higher number of phases?

Is there a reason, beyond historical reasons, that three phases has become the dominant number of phases? I am aware of the advantages against one phase and two phase, namely the reduced amount of ...
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1answer
80 views

Voltage drop-out after lightning strike

A powerful thunderstorm rolled through my area yesterday and something happened that I had never noticed before. Many times before when powerful thunderstorms with lightning rolled through, the AC ...
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5answers
764 views

Why is the supply voltage 400V when the neutral is disabled in a three phase supply?

Why is the supply voltage 400V when the neutral is disabled in a three phase supply? Phase voltage is 230V. Line Voltage is 400V.
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1answer
140 views

range of transmission line?

I am not electrical engineer by profession. So, accept my apology if my question sounds stupid. I am simulating a situation on computer where electric power is being send from one point to another ...
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1answer
1k views

Low voltage power lines - formula for spacing between poles?

What is the distance or separation between pole-pole in a 230 VAC distribution line? Is there any formula for this, or we can take any distance?
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1answer
89 views

Connecting shielding for high and low voltages

I have design a power distribution PCB with high AC(230V) and low DC(<10V) voltage power rails. Both are going to be connected to my board by separate cables. Each of those cables have shielding ...
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1answer
114 views

What would happen to voltage if I connect an extremely long cable to one battery terminal?

Suppose I had a 9 volt battery and decided to connect an extremely long cable to one of the battery terminals as show in the picture below: Assuming that we waited enough time for thing to settle ...
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1answer
85 views

What's the thick wide aluminum tape used for in last mile grid transformers?

This YT video (scrolled to 0:45) shows the process of fabricating a pole mount transformer. At 0:45 the following is shown: there's a wooden brick used to hold everything together, it's covered in ...
3
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1answer
134 views

What does “mod 2” mean in these multi-level inverter switching equations?

I am working through a paper that discusses the design of a multi-level inverter to connect photovoltaic arrays to the grid. It uses 4 PV modules (only two are shown in the design image below, but it ...
45
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1answer
3k views

What is this object found on transmission lines?

What are the components, circled in red in the figure, on this transmission line ?
23
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5answers
3k views

Why are consumers located near high-voltage lines typically not connected to those lines but instead are connected through a lower high-voltage line?

A typical grid uses 110..500 kilovolts lines to deliver electricity to substations which lower that to 6..20 kilovolts and then lines with that lower voltage get to consumers where yet other ...
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2answers
195 views

How much ground current vs. neutral wire current?

This is a follow-on question to an earlier question of mine; I think it deserves its own question, though. I am trying to learn as much as I can about how current in a power grid (transmission and ...
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2answers
169 views

Understanding ground current

I am trying to understand ground current in a power distribution system. The basics, of course, are simple: in the power grid, the "hot" wires carry high voltage, while the return path (the neutral ...
0
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1answer
91 views

what is the Input impedance of transmission line, when source frequency contains two frequency components?

what is the Input impedance of transmission line, when source frequency contains two frequency components? I know the expression of input impedance of a TL, but it assumes that only a single ...
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2answers
663 views

Can we short the neutral to earth (ground) at entry point of our home electrical supply?

Normally in our 230V power outlet, the voltages are as given below. Neutral to Earth - Less than 2V Neutral to Phase - 200V to 230V Earth to Phase - 200V to 230V But nowadays, after around 10 am, ...
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2answers
228 views

how do ceramic disk insulators support the weight of transmission lines?

I know that the transmission lines are held a certain distance away from tranmission towers using those ceramic disk insulation arms and the number of disks is proportional to the voltage of the lines ...
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3answers
749 views

Short circuit protection of cable

I know cables are protected from short-circuit by using fuses / circuit breakers. Cables have I²t curves, which should be checked with fuses or cb's I²t curves in time / current chart. Here I have ...