Questions tagged [power-engineering]

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30 views

Clarification on number of poles(magnetic) and induced/output voltage

I get that turning a loop of wire across a pair of magnetic poles induces a magnetic field. But I don't really understand how frequency plays a role in this. I've read a bit and saw that frequency is ...
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0answers
10 views

Does electrolysis of warm water differ from electrolysis of room temperature water?

Typical energy efficiency of water electrolysis is about 75%. Will this change with the temperature of water?
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1answer
73 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 ...
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2answers
82 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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2answers
78 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 ...
2
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1answer
45 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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1answer
134 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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2answers
73 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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0answers
67 views

Location of breakdowns in power transformers

Where exactly are breakdowns occuring in power transformers? Means, between which components exactly?
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0answers
32 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 ...
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4answers
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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1answer
30 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 :...
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2answers
65 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 ...
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1answer
48 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 ...
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1answer
27 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, ...
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2answers
705 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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1answer
33 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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1answer
131 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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2answers
70 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 ...
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1answer
41 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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1answer
15 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?
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1answer
274 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 ...
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1answer
42 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.
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0answers
49 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 ...
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1answer
64 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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2answers
60 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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0answers
400 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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0answers
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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1answer
144 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?
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2answers
90 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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4answers
171 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 ...
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0answers
27 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 ...
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0answers
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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0answers
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 (...
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1answer
44 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 ...
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1answer
368 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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7answers
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, ...
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1answer
755 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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2answers
135 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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1answer
588 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 ...
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2answers
269 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 ...
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1answer
53 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 ...
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2answers
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 ...
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1answer
18 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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1answer
23 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 ...
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1answer
864 views

Series or parallel overloads in control circuits controlling several motors?

I think that putting the OLs of all the motors in series { figure (1) } provides better protection such that if any one of the motors is overloaded the circuits trips preventing the rest of the motors ...
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4answers
253 views

Why shouldn't we put high voltage cables physically underground?

sorry for the odd title. We're working on a project to find a cheaper and safer way to install high voltage power lines in the Scottish highlands. One of my group mates had a really cool idea to ...
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2answers
192 views

What is the rated tensile strength of 2000 kcmil stranded copper conductor?

All the documentations I could find goes upto only 1000 kcmil. Please direct to a reference for larger cables. Is there a method to extrapolate from smaller cable sizes?
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0answers
46 views

How to solve power surge caused by curing oven PWM cycle?

I have a Despatch LBB 1-69 lab oven in my shop. It is a single-phase, 110-volt, 30-amp unit. It is wired to a 220 volt, 2-phase, 40-amp panel (on a single 110 volt phase), which is fed by the 100-amp ...
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2answers
162 views

Equation for comparing force delivered to road at wheel based on varying gear ratios?

By introducing many new gears and changing the tire size I am altering the torque delivered to a rear bicycle wheel from an electric motor. This then changes the "power where rubber meets pavement". "...