36
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How does turning off electric appliances save energy
Electricity production optimization is a very complex subject. It is also affected by many parameters , which I will try to outline below.
TL;DR: Demand is constantly monitored and supply is ...
- 24.2k
20
votes
How does turning off electric appliances save energy
Timescales on the grid
Power demand fluctations can be broken into timescales from micro-seconds to decades. On the "decades" end of the scale, the power industry and utility regulators work ...
- 449
18
votes
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Why do electric trains arc at high speeds?
Several factors influence this:
at high speed, there's a higher chance of the pantograph losing contact with the catenary wire: at higher speed, bumps in the wire cause a more violent excursion that ...
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10
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How does turning off electric appliances save energy
Yes, they monitor demand and due to differences in how different power stations are controlled they can increase or reduce output to match demand.
Some power plants like nuclear run at full output as ...
- 15.9k
8
votes
Why do electric trains arc at high speeds?
It is due to the high voltage still causing a connection when the contacts separate due to an irregularity (bump etc) between the contact and the wire.
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6
votes
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Extracting power from fusion?
This is an excellent question, and one that has not yet been fully answered by people working in this area of research. Let's look at some of the bigger projects and see what their proposals are:
...
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6
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Why do electric trains arc at high speeds?
As others have posted, a temporary gap between pantograph and overhead conductor is part of the answer, however that's not the complete story. The other big factor is that the train's motors are an ...
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6
votes
How does turning off electric appliances save energy
Peak Demand
One of the biggest issues in the electricity business is managing peak demand. This is the maximum amount of electricity needed at any one time. Typically this will be the middle of the ...
6
votes
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Why do kWh (smart) meters have a maximum operating altitude?
Electronic components are rated for altitude because:
Air density affects convective cooling, both forced and natural, meaning the cooling is reduced at altitude.
Air density affects air's dielectric ...
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5
votes
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Advantages/Disadvantages of two-bladed windmill?
A 2-bladed wind turbine is less stable mechanically than 3 (or more) blades.
Because the two blades are in line, it is much easier to twist the hub of the turbine in the direction along the line of ...
- 12.6k
4
votes
How to calculate hydropower in kW without water head
If you have horizontal water flow (no head) you are extracting its kinetic energy (from its velocity) not its potential energy (from its head).
So you need to know the velocity of that flow as well ...
- 1,630
4
votes
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Why shouldn't we put high voltage cables physically underground?
Your four drawbacks are very good reasons for not laying cables on the ground and just covering them with soil or "stuff".
Erosion will be a major issue. Exposed cables would be a safety hazard to ...
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4
votes
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Question about flow temperature and storage temperature in a cogeneration plant
when the cogeneration plant switches of upon reaching 85°C flow and without another heat source, there's no way to reach 95°C.
Are you sure the switch-off happens at 85°C flow, and not at 75°C return ...
- 4,781
4
votes
Advantages of hydrogen gas turbine over fuel cell
I've read in one of Smil's books that fuel cells are somehow limited (in what sense I'm not sure anymore but I believe it was power output) by their "active area". I'm having difficulties learning ...
- 542
4
votes
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Power systems unclear voltages
Note the problem specifies the load is "delta connected". There is no neutral connection to measure phase voltage ($V_{LN}$) against.
Also note the supply frequency is 60 Hz. 208 V is a ...
- 361
3
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Why do electric trains arc at high speeds?
The upforce on a pantograph is 15-40 pounds, 60 pounds at the outside. (7-18kg, max 30 or so).
The trolley (contact) wire is made of solid bronze or copper, typically 4/0 to 400kcmil (107-200mm^2), ...
3
votes
How does power generation (hydro, wind etc...) account for variable power consumption?
This is more of an addition to the previous answer by blacksmith37. I think it might be more appropriate as a comment, or perhaps an edit to the previous answer. With no ability to comment at this ...
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Advantages/Disadvantages of two-bladed windmill?
One of the advantages of two blades over three blades is less materials are required to make the blades.
The disadvantage of a two bladed rotor compared to a three bladed rotor is due to the ...
- 9,712
3
votes
Doubt on a shaft-turbine-generator system
I am not entirely certain about your question but I think, it basically boils down to this equation
$$M = I \alpha $$
where:
M is the torque applied
I is the mass moment inertia of all rotating ...
- 24.2k
3
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Why do kWh (smart) meters have a maximum operating altitude?
Expanding item 2 in Tiger Guy's good answer I'd say it's definitely about dielectric strength.
Electronic devices manufacturing standards (e.g. IEC62368-1) define creepage and clearance distances ...
- 295
2
votes
Why shouldn't we put high voltage cables physically underground?
I do not know the laws in your country, but the key is "risk assessment". And the risk we are talking about is the risk of killing someone, not the risk of the cable being damaged.
Irrespective of ...
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2
votes
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Power assist mechanism for double pendulum?
Perpetual motion pendulum desk toys have a magnetic coil in the base that is pulsed at the correct pendulum displacement. This applies a small assisting force to the permanent magnet in the pendulum ...
- 8,226
2
votes
Choosing the best type of portable cord for a consumer electronics product
The choice of cable is down to the environment that the cable is working in.
Designers will be looking at mechanical abuse - by accident or not, temperature, chemical hazards etc.
So, taking your ...
- 15.9k
2
votes
Why do electric trains arc at high speeds?
It's not about voltage*, it's about current.
*line voltage
When a high-current circuit is interrupted (especially an inductive one), an arc is formed between the contacts breaking away. The high ...
- 426
2
votes
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Maximum amps from a switching voltage regulator
That is an oversimplification.
From the data sheet http://www.ti.com/lit/ds/symlink/lm2596.pdf there are two relevant features, internal over-temperature protection and a maximum current limiter (...
- 12.6k
2
votes
Accepted
Calculation of the specific CO2 emission of a cogeneration plant for the produced electricity
Your basic logic is sound: You compare the case of the cogeneration plant + boiler vs. boiler alone. Your math looks correct to me.
Where did you get the value 215 g/kWh from? All (german language!) ...
- 4,781
2
votes
Why are hydropower plants always wheel-shaped and not flat?
The incoming stream of water flow momentum is transferred to the radial blade of the turbine wheel when it hits the slow blade of the turbine, giving it its kinetic energy, and pushing it out of the ...
- 22.6k
2
votes
Accepted
Sun as water pump in underpressure water power circle
I have seen this design a couple times before. Not sure what it is called. If I were to name it I would probably call it a "2 phase thermosiphon gravity turbine generator". It would ...
- 8,226
2
votes
Would it be possible to generate electricity from continental drift?
If not lending ourselves to overly unrealistic scenarios, then no. In theory however, then yes.
According to National Geographic, "The North American and Eurasian tectonic plates, for example, ...
- 369
2
votes
What properties are most important for a fluid in the generation of steam power?
Is it the most efficient? Maybe or maybe not, but it is an outstanding medium to turn into vapor for use in a turbine. It is extremely plentiful, the heat of vaporization is high, and it is easy to ...
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