Questions tagged [power-engineering]

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1 vote
3 answers
77 views

Would it be possible to generate electricity from continental drift?

It definitely wouldn't be practical compared to other sources of energy, but given currently plausible technology, would it be theoretically possible to use the movement of tectonic plates (as in ...
0 votes
1 answer
19 views

Automatic car applying (seemingly) more torque upon throttle "liftoff"?

I drive a relatively average powered automatic transmission front-wheel drive car; my (naturally aspirated) engine delivers maximum torque at around 5000 RPM. I performed the following test (remaining ...
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0 votes
1 answer
21 views

How to find pixel density in LED Display Board?

How to find pixel density in LED Display Board? How do we compare pixel per inch and dots per inch? In this example, a screen of 16'x9' is shown. How did they calculate 4875x2710P and 975x548p and so ...
0 votes
1 answer
47 views

Basic questions about power grid stability with variable loads and sources

I am curious about integration of renewable energy in electricity grids. I am a mechanical engineer and understand energy and power but I have little knowledge about electricity. I will be thankful if ...
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0 votes
2 answers
102 views

Doubt on a shaft-turbine-generator system

Consider a shaft which connects a turbine to a generator. Initially, none of the parts are moving. Now the turbine starts to rotate and the torques act on the shaft from both the turbine and generator ...
0 votes
1 answer
42 views

Power systems unclear voltages

I was looking at this problem: "A balanced delta connected impedance load with (12+j9)Ω per phase is supplied by a balanced three-phase 60 Hz, 208-V source " I do not wish to ask for help at ...
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-1 votes
1 answer
200 views

Line to neutral voltage in three-phase power systems

I have the book "Power system analysis and design" by Sarma. In his intro to balanced LN voltages, in chapter 2 p62 he states: $$V_{LL} = \sqrt{3} V_{LN} \angle30º$$ but later in the chapter,...
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0 votes
1 answer
94 views

Line to line voltage

I have a question regarding power electronics. What is the meaning of 'line to line voltage' what does it tell us and how can this be calculated. Say I have a three phase system how would one find the ...
2 votes
2 answers
89 views

Sun as water pump in underpressure water power circle

Introduction A water storage power plant pumps water up to a reservoir when there is more power available than needed and lets the water flow down when power is needed. For pumping water up, ...
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1 vote
2 answers
82 views

What happens if an entire country turns off all lights and electric devices during peak consumption hours? [duplicate]

I've been reading about smart grids but I studied Computer Engineering and my already limited knowledge of power systems is very rusty. I keep hearing that traditional power stations have to adjust ...
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2 votes
1 answer
94 views

Can a level shifter convert power from 3.3v to 5v and then back to 3.3v?

I need a digital output from a raspberry to power a stepper driver that takes 5v as input. After that, the output from the stepper driver must be converted back to 3.3V because a Pi can't handle 5v on ...
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2 votes
3 answers
492 views

Why are trams always electrified with DC, while trains can be electrified either with AC or DC?

Trains can be electrified either with DC voltage or with AC voltage. Various networks across various countries uses various standards. My question is however for trams, which are basically a lighter ...
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0 votes
2 answers
85 views

Why are hydropower plants always wheel-shaped and not flat?

Question: Why are there no flat power generators like in the picture below, that work on the surface of shallow, but steadily flowing rivers ? (As a floating micropower plant.) The picture shows a ...
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0 votes
0 answers
205 views

Location of breakdowns in power transformers

Where exactly are breakdowns occuring in power transformers? Means, between which components exactly?
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1 vote
0 answers
38 views

What's the smallest hydropower plant that can blackstart a grid?

One of the most underrated capabilites of classical, large-scale hydropower plants is their ability to "black start" a dead electric grid. I'm not going to go into details on the blackstart ...
22 votes
4 answers
4k views

How does turning off electric appliances save energy

We all know if we use less electricity we save energy. But the energy we're getting is result of burning (not necessarily the literal meaning) the fuel. Even if we don't use that energy that fuel is ...
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2 votes
1 answer
36 views

Transformer Phase Fault

I have a transformer for troubleshooting. It is a 3 phase DELTA-WYE Step down (11KV/400V) transformer, the low side voltages (secondary) are Line to line voltages: RED-YELLOW : 400 V YELLOW - BLUE :...
3 votes
2 answers
181 views

Advantages of hydrogen gas turbine over fuel cell

In the setting of large-scale electricity generation, I was wondering why one would want to burn hydrogen in a gas turbine instead of using it to power a fuel cell. Aren't fuel cells more efficient ...
-2 votes
1 answer
59 views

Thrust by turbo fan jet engine

How much thrust can I produce with a turbofan jet engine without injection of fuel and with just compression of air, which will be heated by convection if initial temperature of air of 20 oC and its ...
-1 votes
1 answer
31 views

How a turbo jet engine produces thrust

As i read on some website of nasa, that velocity of the gas flowing from nozzle of the jet is responsible for thrust, But ky confusion is that, as the velocity increases presure should drop at nozzle, ...
7 votes
2 answers
2k views

Calculation of the stored energy for a heat storage tank

There is a heat storage tank that is directly loaded from the top and the heat is also taken from the top. The colder water from the heating circuit return flow enters the heat storage tank at the ...
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3 votes
1 answer
39 views

Question about flow temperature and storage temperature in a cogeneration plant

Let's assume I have a cogeneration plant that produces heat with a nominal output. The heat is given into a heat storage tank, which is filled from above. The maximum flow temperature of the ...
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5 votes
1 answer
262 views

Calculation of the specific CO2 emission of a cogeneration plant for the produced electricity

Suppose I have a cogeneration plant that runs on natural gas and produces heat and electricity. The heat effeicieny is $\eta_{th} = 0.4$ and the electricity efficiency is $\eta_{el} = 0.4$. The ...
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-1 votes
2 answers
81 views

Finding replaceable push pull transformer with similar specifications

I am a student and is making power project using Push-Pull transformer. I used the Reference design: TI Designs: TIDA-01352. I stuck to find 2 replaceable Push-Pull transformers as in suggesting ...
1 vote
1 answer
42 views

What's the function of those coils there?

What do they do? The aux contacts are normally open and the device is MR PQM 500 reactive power compensation system.
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2 votes
1 answer
18 views

Maximum amps from a switching voltage regulator

Looking at a part like this LM2596 It is rated for 3Amps with a voltage range from 3.3-12 volts. Does that mean that this voltage regulator will only output a maximum of 3amps?
2 votes
1 answer
533 views

How do multiple enphase microinverters stay synced to the grid?

In a prior question it was established that any string or microinverter that is grid tied must put out sinusodial power. But there is also the task of being in sync with the grid. It seems from ...
0 votes
1 answer
47 views

Cannot understand an equation related to impedance. (Power system analysis)

Can someone explain how can we find |Z| term and also from where does the cosine term arrive at the final equation.
1 vote
0 answers
53 views

How is a Steam Power Plant designed?

I asked this question at physics but i think this suits it more. I'd like to know few things about how does one design a Thermal Power Plant? There is something fundamentally lacking in my knowledge ...
0 votes
1 answer
79 views

Relationship heat rate with capacity

I am an economist, so please keep replies simple ;) I am searching for the relationship between heat rate and capacity for gas-fired power plants. Here is what I refer to as heat rate, i.e. the ...
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1 vote
2 answers
61 views

Power torque and rotational speed of a not running yet DC motor

If the power $P = C\omega$, so how a DC motor powered by $P = 10\text{ W}$ can work as $\omega$ is of course 0 rad/s at first, because if $\omega = 0$, then $P = C\omega = C\cdot0 = 0$?
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0 votes
0 answers
496 views

How to calculate the register draught/draft loss (RDL) of a burner?

I am aware this is a vague question but it is something which has been on my mind. Would anybody know the steps used to calculate the draught loss across a burner in the furnace of a boiler? Would ...
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0 votes
0 answers
37 views

Ineffective purging of a flame monitor lens

There is a wall-opposed flame monitor detecting coal, oil and gas combustion in the burners, attached to the furnace walls in a coal-fired power plant. I'm looking for suggestions to clear the dust ...
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2 votes
1 answer
176 views

How Can I do punching of 0.22mm in stainless steel sheet (Sheet thickness 0.5mm)

Wanted to press punching of 0.22mm dia (Bottom) and on (top) 0.6mm dia Please suggest how can I make such die?
user avatar
0 votes
2 answers
102 views

Working mechanism of photovoltic cells

In the textbook : Electric Power Principles, in Chapter 1 on the working of a pv cell : The source current Is is the result of absorption of photons in sunlight that cause separation of ...
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3 votes
4 answers
173 views

How does power generation (hydro, wind etc...) account for variable power consumption?

I know in a power distribution system, the power is generated (from a dam or turbine or something) and consumed immediately. But the power consumed is variable. So how does the generation system take ...
1 vote
0 answers
34 views

What is the twisting rate to reduce capacitance load on DC power transmission line?

I need to carry dc (direct current) electrical power from a solar array to point of use. I know that an undesirable capacitive load will develop if I just run the power and neutral wires parallel to ...
1 vote
0 answers
31 views

How to calculate and common capacity factors for gas power plants

I am wondering the following, and didn't find anything online or here in the forum: 1) How is the capacity or load factor of a gas power plant calculated: (GROSS electricity generated)/(maximum ...
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1 vote
0 answers
39 views

I would like to run a smartphone using a primary battery instead of rechargeable for a project. What are the 4 contacts used for on the factory LiPo?

Most phone batteries will have a connector of some type with 4 contacts. Of course two of those I'd expect to be +- Voltage, but the other two compose some sort of mystery input to the phone (...
0 votes
1 answer
50 views

Choosing the best type of portable cord for a consumer electronics product

Consumer-level electrical portable cords come in a variety of types (and gauge, but that's not the subject here) and each must have its rationale, considering the cost constraint (performance/price ...
1 vote
1 answer
448 views

What ramping constraints for gas plant - CCGT, combustion and steam turbine?

I am using the publication Current and Prospective Costs of Electricity Generation until 2050 to source ramping constraints for an economic model of three different gas power plants - CCGT, combustion ...
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8 votes
7 answers
7k views

Why do electric trains arc at high speeds?

When I watch videos of high speed trains I always see explosions of electricity near the top, or arcing. Why does that happen? I know that the Acela does it a lot but other high speed trains have it, ...
1 vote
1 answer
828 views

Difference between gas combustion engine and gas turbine?

I am a non-engineer and I am using a gas power plant data base. Some plants listed are of the type "combustion engine", some of the type "gas turbine", some "steam turbine" and some "combined cycle". ...
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2 votes
2 answers
169 views

Extracting power from fusion?

If we are able to create a fusion reactor so there is a net gain in energy how can we turn the heat into electricity. I know how it is done normally for fission, steam, but how could this be adapted ...
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0 votes
1 answer
627 views

What is the maximum efficiency of a mechanical electric generator?

If we apply a simple push to rotate a system of gears to generate electricity, what is the maximum practical and theoretical power efficiency of the system, assuming the push as the only source of ...
1 vote
2 answers
295 views

Power assist mechanism for double pendulum?

I'm making a double pendulum for an art installation, and I would like to add energy to the system to compensate for friction and air drag losses so it can run more or less indefinitely. The design ...
0 votes
1 answer
55 views

How many batteries can I charge and how long would it take?

Using a hydro generator which gives an output of 4.838KW, I am trying to figure out how many batteries I can charge and how long it would take. I am doing the calculations based on 12V, 17Ah ...
1 vote
2 answers
2k views

How to calculate hydropower in kW without water head

I am trying to do some calculations to figure out how much power output would be produced from a water powered generator that uses horizontal current flow to move the generators coils rather than ...
0 votes
1 answer
19 views

If I made a incandescent light bulb filament smaller what would happen? [closed]

If I took the filament in the bulb and made it smaller, and also increase the thickness of it, what would happen?
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-1 votes
1 answer
24 views

Doubt on power generation by hydraliuc turbine [closed]

What happened to the final power generation if the hydraliuc turbine rotates discontinously for example if a turbine runner rotates with 2000 rpm for 2 minutes and stop rotating for 4 seconds and ...