# Tag Info

41

Janka comes close, but there are are several more details. (Note, recalling from EE classes about 45 years ago.) On many high voltage lines there are arc electrodes at various points. When lightning strikes the line, the increased voltage causes an arc to form across the electrodes. This helps to dissipate the voltage of the lightning strike. But the ...

32

Lightning brownout procedure: When lightning hits an overhead power line, there is overvoltage at first, for about 100 milliseconds. This overvoltage creates an arc at a nearby pole. The arc works as a short circuit, so current from both sides of the overhead lines flows to the arcing pole. The voltage at other places of the grid dips because of the huge ...

19

A good question. The excess of generator drive power over generator load will cause all of the generators on the grid to start speeding up. For a small over-power, there will be time for the mechanical steam valves and water valves to start closing, and reducing power to the generators, which will slow them back to nominal speed. For a large over-power event,...

18

Taking, at random, Overland Park, Kansas, as an example: Population 191,278 (2017). Area 195 km2. Annual energy demand (per capita) 13,500 kWh = 37 kWh/day. World Bank. City demand = 191278 x 37 = 7 x 106 kWh/day = 7 x 109 Wh/day = 3600 x 7 x 109 = 25.5 TJ/day. For pumped storage the formula for energy stored is $E = mg\Delta h$. Assuming we could ...

18

I am not sure exactly what you are expecting as an answer, but storage has already started to be used to supplement all energy sources. Utility-connected battery banks have already proved superior to any alternative peaker plant. This report on the Australian 129MWh Tesla battery installation's first year of operation could shed some light on it. In just ...

14

A power plant rated at 1GW can produce 1GW of power, at the rated conditions. If it has an efficiency of 20%, then it will be consuming 5GW of energy in some form to do that. If the power plant is (say) thermal steam, then the calculations are fairly easy, because we can assume that it can do this continuously, as long as fuel arrives. It will generate ...

13

You are paralleling two synchronous generators: as soon you connect them to a common AC network, they are phase-coupled, and this automatically means they have the same speed, too. Regardless of the wind speed. If the wind speed is lower at one turbine, that generator will work as a motor and make the turbine act as a fan. So … don't do that. You have to ...

12

It depends on the letter(s) after GW. A 1GWe plant produces 1GW of electrical power. At 20% efficiency, it will have to get rid of 4 GW heat. You will sometimes see 1GWth - that produces 1GW of thermal power; as you have told us its efficiency is 20%, it'll produce 200MW electrical power (200MWe). But no practical thermal plant of that size will have ...

10

Part of your basic premise is false: gas turbines can go from zero to full power in a matter of minutes. They've been used to provide peaking power for decades, since it's rare for power demand to vary so rapidly that they can't handle it. Because traditional generation capacity can be changed so quickly, there's no need to store electricity on more than a ...

9

Curiously, a blackout would occur. All generating stations, suddenly bereft of demand, will spin faster, voltage will rise, so their protections will trip, shutting them off-line. This happened to some of the stations during the 2003 North American blackout when the grid separations occurred. The funny thing is that it would take quite a while to get the ...

8

Further to Neil's answer: For tiny amounts of over-power (e.g. when a machine is switched off) the excess power is consumed by the remaining connected loads. During over-power, all loads are exposed to a small amount of excessive voltage, and thus they generally draw more current and dissipate more power. These tiny fluctuations are usually not regulated out....

6

Not if they're not moving. What induces a current in a coil of wire is a changing magnetic field, so a static one won't do anything.

6

It could be the generator, but it's more likely to be the type of loads being driven. A simple rectifier/capacitor DC supply draws current only around the peaks of the supply voltage waveform, giving rise to a current with lots of odd harmonics, and a 'clipped sine' voltage waveform. This type of supply was prevalent in computers, TVs etc for a long time, ...

6

Looking at websites of people who have much experience in this area is an excellent start. The few example sites I mention below vary in how much theory and alternator design they offer but some are reasonably good. I have not looked at any of them in any detail for some while, but some will get into flux, magnet sizes versus field depth, core materials / ...

6

What you need to look for is two metals with a large "Galvanic Potential" between them. This is also known as a metals Anodic Index. Copper and Zinc is just one of many options. The following is a partial chart of Anodic Indices of various materials: Image source here. As you can see, Copper is quite Cathodic at $-0.35\mathrm{V}$, while Zinc is quite ...

6

All that energy is being send to the ground instead of used. No it's not. This classic misconception is probably the origin of all these "harness the lightning" ideas. Actually, the voltage across the ground is insignificant compared to the lightning itself. Instead, imagine that the lightning is a tungsten filament, or lightning is like the ...

5

You need to split the transformer like this to get any significant induced voltage: - The magnets should be spinning close to the centre core limb and now the flux is forced to pass through the iron of that limb. When you had this setup: - The "I" part of the core is preventing any significant amount of flux passing into the central limb of the transformer ...

5

They mean terawatt-hours. Terawatts per hour is not a thing, but if it was, it would be TW/h. By 539.9 TWh in 2010 they mean for the entire year, i.e. 539.9 terawatt-hours/year. Useful to economists, not useful to engineers. But we can obtain plain terawatts. With 365.25 days in a year, hours/year is 24x365.25 or 8766. To get plain terawatts, ...

5

reconductor is a verb. to reconductor means to replace conductors

4

In a coal or nuclear plant, the thermal power changes very slowly, perhaps 10-20% per hour. To have power available for spinning reserve, the steam turbines are run at a lower power than the boilers, the main throttle is set so that there is some steam available but not used. The excess steam bypasses the turbine and its energy is wasted. If more power is ...

4

How does some god knows what voltage and frequency generated at a dam ends up as steady 50 hz sine wave household voltage It's 50Hz when generated - the generators are built with a number of phases and run at a constant speed. Whether it be a thermal power station or nuclear power station or a hydroelectric damn its impossible to keep all the dynamos ...

4

Inductive voltage regulation The traditional bicycle dynamo's (see note) output voltage will vary roughly proportional to speed. If this problem is not addressed the lamps - its intended load - will be very poor at low speeds and the bulbs will blow at high speed. The solution is to design the system - dynamo and lights - as a complete package with enough ...

4

The fact that thermocouples produce a (relatively low) EMF is key to understanding how to get power out of them. You can't do anything about the EMF of a single junction (for a given temperature difference, which is limited by your heat source and material melting points) but you can increase the current by reducing the electrical resistance (i.e. using ...

4

While I cannot speak for the specific project you are talking about (my Spanish isn't so great), DC transmission lines are most definitely feasible. High-voltage DC (HVDC) has several advantages over AC transmission, one of the more significant ones being that it allows power to flow between AC grids with different frequencies or phase angles. The List of ...

4

How much electricity will these power plants with a cumulative capacity of 200 GW produce? 200 GW will be the peak output power and for solar this will be at optimum solar conditions. I also have information that solar power plants in these countries run with an efficiency of 20%, but I'm just confused. So they will take 1000 GW of solar energy and ...

4

The "fast" response you're thinking of is called frequency response. The grid consists mostly of generators and motors which "electrically" rotate in sync with the grid (the physical rotation being different by the slip). When the load on the grid exceeds the supply, they slow down and frequency decreases (slightly). When the power input to the generator is ...

4

From Wiktionary: reconductor (electronics) To replace the cable or wire on an electric circuit, typically a high-voltage transmission line, usually to afford a greater electric-current-carrying capability. TESMEC, an Italian grid infrastructure contractor, provides this description of reconductoring (emphasis added): Power transmission owners and ...

4

If the frequency is in fact identical, then the phase angle will never change. However, this is not what is meant by that sequence of instructions, nor what happens in practice. Getting the frequencies equal means nominal frequencies, getting it fairly close. With an unsynchronised generator, any slight change in drive power will alter the frequency slightly....

3

I think it helps you understand when you think of an electrical machine as both a motor and a generator. They are both at the same time, and when they are running on a power grid, they support each other. Synchronous AC machines running on a grid indeed all run at fixed speed. And they all have a fixed voltage too, which is both set by the grid. As the ...

3

So let's say I have a very basic home grid set up. Before we start, because of the nature of your questions, I want to advise you not to actually connect anything you designed to the mains until you have a much stronger understanding of electrical design. You could easily start a fire or electrocute yourself or someone else if you mess around with your ...

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