Questions tagged [power-engineering]
The power-engineering tag has no usage guidance.
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Converting RMS to Maximum Power
If I have a sinusoidal voltage signal of amplitude $V_m$ driving a resistance $R$, what is the relationship between the RMS power $P_{rms}$ and the maximum power $P_{max}$ delivered to the resistance?
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Can I use a UPS in front of my A/C heat pump, to reduce surges in the house?
Hopefully this is on-topic here. I'm open if I should as on another SE site.
We have an air conditioner heat pump outside, typical to most homes with one. When it kicks on, many of the lights dim for ...
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Why do kWh (smart) meters have a maximum operating altitude?
At first I thought it was a bad translation from Chinese to English, but it turns out that many data-sheets of kWh power meters mention a maximum altitude, usually below 2 or 3 km.
For example:
...
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natural gas-fired power plants
I live in Tunisia, a country of 12 million inhabitants where natural gas (provided essentially by Algeria) is used in power plants. I'd like to know how it is that natural gas can contain so much ...
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What will be the destiny of the oxygen gas created in the future hydrogen economy?
When I was recently studying biomass-to-electricity (gasification methods, Drax power station...), I was wondering whether the efficiencies of these systems would not benefit from a source of pure ...
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What properties are most important for a fluid in the generation of steam power?
I was curious if water is the most efficient fluid for use in generating steam power. I thought it might be, since it has the highest latent heat of evaporation of any fluid. I wasn't sure if other ...
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How are a Horizontal Axis Wind Turbine's blades joined to the hub, allowing them to rotate?
I know its a basic question for this site.
But I couldn't find the answer on google so I beseech thee.
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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 ...
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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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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 ...
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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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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 ...
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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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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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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 ...
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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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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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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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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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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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Location of breakdowns in power transformers
Where exactly are breakdowns occuring in power transformers? Means, between which components exactly?
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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 ...
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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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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 :...
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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 ...
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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 ...
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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, ...
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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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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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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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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 ...
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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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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?
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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 ...
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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.
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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 ...
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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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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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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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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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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?
user15441
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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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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 ...
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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 ...
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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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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 (...
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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 ...
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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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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, ...
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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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