Power Definition and 998 Threads

  1. Pythagorean

    Stirling Engines for Home Power

    Would it be a feasible power source to have several Stirling Engines sticking through an outdoor wall near your fire place in a cold climate? Issues I can think of: Presumably it would be a heat sink and require you to consume more firewood. Engineering it to not have passive leaks might be...
  2. abolfazlghasemi

    Hydrogen dew point in power generators

    Large power generators (for example 200 MW) are cooled by H2 in gas form. H2 temperature is +45 to +75 "C. So why hydrogen dew point is important in generator while the lowest hydrogen temperature is 45 "C? And in some Power Stations is monitored online... Thanks, a lot
  3. K

    How do I properly connect a bench power supply to a pulse generator for testing?

    Hello! I am sorry if this questions is silly but I really don't know much about electronics. I have a pulse generator (this one) and I want to test it with a low voltage for now. I have a bench power supply (something like this). I am confused about how to make the connections. For the pulse...
  4. M

    Find the highest power of ## 3 ## dividing ## 823 ##

    Let ## n ## be a positive integer and ## p ## be a prime. Then the exponent of the highest power of ## p ## that divides ## n! ## is ## \sum_{k=1}^{\infty}[\frac{n}{p^{k}}] ##. Observe that ## n=823 ## and ## p=3 ##. Thus \begin{align*}...
  5. S

    Power Amplifier and Exciter, Impedance / Power

    Hello. I have a question regarding an power amplifier (signal generator). I have three exciters and want to connect them to the power amplifier. One exciter have a impedance of 8ohm and power of 25 watt. The ampliefier have one output with the electical data: 4 ohm : 500watt; 6ohm: 330 watt and...
  6. R

    "Ground" and "Center Tapped" Power Transformer Secondary in guitar amp

    Hello - thank you for reading this, and thank you in advance to anyone who replies and clarifies the mystery of "ground." I have finally gained a full understanding of how a full-wave rectifier, two-power tube electric guitar amplifier works in a push-pull manner, but one thing remains after I...
  7. E

    I Acceleration From Rest Under Constant Power

    Impossible?!? By my estimation the equation that describes this motion is given by: $$Pt = \frac{1}{2}m{ \dot x}^2$$ or $$\dot{x} = \sqrt{\frac{2P}{m}} \sqrt{t}$$ but this implies: $$\ddot{x} = \sqrt{\frac{2P}{m}} \frac{1}{\sqrt{t}}$$ So, no matter how small we make the power, we appear...
  8. D

    Uninterruptible power supply output specifications

    Why do some UPSs have both Volt-amp and watt rating? According to APC, the connected load shouldn't exceed the UPS's VA and watt rating. Why? If I had a UPS with 1000VA and 500W rating, why can't it power a load consuming 1000VA @ 900W? If a UPS can output 1000VA, why does it care how much...
  9. WumTrudo

    How Do You Calculate Engine Power for Semi Trucks in Various Conditions?

    Summary: Calculating engine power required for semi trucks under different circumstances. Hello everyone, I would like to ask you for help if that is allowed. For a current project I need to calculate engine power needed in watts under different circumstances. This is something that I will...
  10. M

    Prove that ## n ## must be a power of ## 2 ##

    Proof: Suppose for the sake of contradiction that ## 2^{n}+1 ## is prime but ## n ## is not a power of ## 2 ##. Then ## n=ks ## for some ## k\in\mathbb{Z} ## where ## 1\leq k<n ## and ## s ## is an odd prime factor. This means ## (a-b)\mid (a^{q}-b^{q}) ##. Let ## a=2^{k}, b=-1 ## and ## q=s...
  11. Martinz

    Power factor of motor with VSD?

    If I have a motor with a full load power factor of 0.8 and starting power factor of 0.3 and I install a VSD to run it with a datasheet power factor of 0.95, will the power factor during starting be 0.3 or 0.95? And at full load? Cheers!
  12. rsc9421

    A Power consumed by electron gun

    First Assume the following basic circuit: I read in many textbooks that the electrons in the circuit are accelerated by the positive voltage and decelerated by the collisions, so the speed is constant. We also know that the circuit current is I = 10A so the power consumed is P = V * I = 100W...
  13. anorlunda

    The History of 3-Phase Power, (and AC/DC, 50/60 Hz, US/Euro, ....)

    Kathy Joseph makes wonderful videos (and now a book) about the history of electricity. Her research is very thorough. I just watched the video below, and found it instructive. Especially interesting is how Nikola Tesla and Westinghouse in the USA got the fame and credit for three phase power...
  14. J

    How Do You Find a Recurrence Relation for a Power Series Solution of an ODE?

    I believe I am doing everything right up until the point where I have to try and find a recurrence relation. I honestly have no idea what to do from there. I've listed my work in getting the powers of n and the indicies to all match. Any help appreciated. Here is the original DE...
  15. K

    What does the 'power' vs 'time' graph look like for a 3 phase AC supply?

    Hi, For years I wanted to understand why we have a 3 phase supply and not a 2 phase supply in AC. In Quora I found an interesting answer and was convinced about the purpose mentioned: Answer to Why there is no two phase electrical inputs instead of three phase and single phase? by Paul...
  16. M

    MCNP Flux and Power Calculation

    During a reactor assembly calculation, I need to determine axial and radial flux distribution over the surface. When I use F2 and F4 tally I get some value with unit 1/cm**2 What does the value means, neutron flux is supposed to be in the 10^14 range but output values are 10^2 range. Can anyone...
  17. J

    How are coils arranged in a power station generator?

    Hi, I wanted to know a couple of things regarding the construction of the stator and rotor of a generator in a power station. Firstly, how the copper windings inside the stator are arranged. I understand it’s a three phase winding where each phase has a set of two coils like this: Source...
  18. Y

    Funny observation in matching BJT power transistors

    THIS IS NOT HOMEWORK I design audiophile power amps as hobby. I need to match power transistors. It is A LOT HARDER than I thought. I built a test fixture to hold up to 50 transistors at a time. I try to match sets of 13 to about 1mV which is very tight as Vbe change is about -2mV/deg C. I have...
  19. A

    Effects of brownouts and power spikes on linear power supplies

    What are the effects of brownouts and power spikes on linear power supplies in particular; e.g., a linear power supply that provides 24 V to an inductive angle encoder? Thanks for any information you could provide.
  20. amazingjoe

    Could you use Solar to power a DC to AC Inverter? (Description below)

    I'd like to take Solar Panel power output and use it to power an AC outlet on the ultra-cheap. I know a lot of people use Solar to connect to a purpose built inverter and also have a battery somewhere in the mix to provide a stable output but wondering if the following (using the assumptions...
  21. T

    I Voyager Spacecraft beginning to Power Down

    An interesting article on some of the history of, and discoveries by, the 44+ year old Voyager spacecraft s. The bean counters originally planned a 4 year mission for Voyagers 1&2. However, the scientists and engineers involved saw a golden opportunity that wouldn't repeat for another 176...
  22. C

    I Acceleration as a Function of Time Using Constant Power

    Hello everyone! I was doing some dimensional analysis to find an equation that gives a acceleration as a function of time, using constant power. I came up with the equation $$a = k\sqrt {\frac P {mt}}$$ I differentiated velocity with respect to time in order to check my work and also checked out...
  23. J

    Misc. Help with power wheelchair modifications

    I have a jazzy pride 1121 power wheelchair that I need help with. I have installed larger tires so I wasn't limited to where I could take it in my yard. Because of the increased size of the wheels, it now lacks the power to climb inclines. I was told that possibly a more powerful controller...
  24. SuperPat

    B How to Calculate Power and Torque for a 15kg Load at 15 RPM?

    Hi all I am Belgian and I have difficulty with english formulas. I'm trying to calculate the power and torque required of a motor to rotate a load. Here is the problem: I have a motor (axis up) on which is fixed a cylindrical load of 15Kg. The diameter of this load is 400mm Calculate the power...
  25. anorlunda

    The Grim Power Outlook Spreads Beyond Texas

    This year, the grim outlook goes to other parts of the USA. Not just Texas. NERC is the most credible source we have for US electric reliability topics.
  26. samy4408

    I Question about X-ray power emitted by the Coolidge tube

    hello i found this equation in a course about x rays , and i couldn't find it anywhere else they said that it is the theoretical expression of the energy spectrum , and dφ/dE is variation of the power emitted by the Coolidge tube as a function of the energy of the x ray. but i didn't understand...
  27. T

    Calculating Force on Shaft Bearings - Hydro Power Systems

    I know the moment of inertia and the rotating speed of a shaft, and the allowable vibration is 2mm/sec. How is the force calculated? What is the formula to calculate the force on the shaft bearings which are a know distance from centre of gravity? Thanks
  28. A

    What is the Power Loss in a Transformer?

    ##\frac{N_S}{N_P} = \frac{240}{12\times 10^3} = \frac{1}{50}## ##I_S = \frac{N_P}{N_S}I_P = \frac{N_P}{N_S}I_P = 50\times 2 = 100## Amps ##P_{loss} = I_S^2R##, but I don't know how to find R
  29. T

    Optical power of Smartphone (Galaxy S20) torch

    In doing a project on phototransistors I am using my smartphone as illumination source. In order to find the responsivity of the induced current from the light, I need to know the surface power density, which I could estimate, if I knew the effective optical power of the light from the...
  30. leifh

    Question about electrical power compared to mechanical power

    I am new here and I am seeking for help:) Thank you so much. In engineering, electrical formula often analogy to mechanical formula. eg. power[W] = pressure x volume flow rate vs power[W] = voltage x current My question is could we make the simplest unit between electrical and mechanical...
  31. A

    Adjusting the Power Factor of an RLC circuit

    a) An inductor should be added because that would cancel out the lag of the voltage with the current so that P = IV is at a maximum since V is ahead of I in an inductor b) ##cos(\phi) = \frac{R}{Z}##, ##R = Zcos(\phi) = 60\times 0.5 = 30 ohms## ##X_l - X_c = \sqrt{Z^2 - R^2} = \sqrt{60^2 -...
  32. P

    Parallel RLC Admittance, Current and Power Vector Diagrams

    (An even longer-winded version was written and deleted out of mercy.) Assume an AC voltage at zero degrees applied to an ideal parallel RLC circuit. For a predominantly inductive circuit, the vector diagram for current should show the supply current in the fourth quadrant (i.e. with lagging...
  33. Algr

    Why does demand knock power plants offline?

    https://www.cnn.com/2022/05/14/us/texas-heat-wave-ercot-conserve/index.html Why would they make plants like this? If demand gets too high, the plant just stops? And potentially knocks out other plants? Wouldn't it make more sense to cut off a few places at a time so that the plant can...
  34. gremory

    A Power series in quantum mechanics

    Just earlier today i was practicing solving some ODEs with the power series method and when i did it to the infinite square well i noticed that my final answer for ##\psi(x)## wouldn't give me the quantised energies. My solution was $$\psi(x) = \sum^{\infty}_{n=0} k^{2n}(\cos(x) + \sin(x))$$...
  35. Melbourne Guy

    Our space ship has lost power, what happens now....

    I'm about 25,000 words into my latest novel and the story arc is coming together nicely, but one aspect I need thoughts on please is what would happen inside a spaceship that has been grievously damaged in battle to the point that it has been abandoned by the fleet as a 500m long wreck...
  36. PhysicsTest

    Negative Power Supply Clarification

    I am confused with the negative voltage supply connections in electric circuit. If i have circuit as below with -5V source it is same as below In the 2nd circuit the 5V is directly shorted with the ground, does it mean the circuit is not correct? Am i missing something? Please advise.
  37. F

    Engineering Power Flows and Losses in a line between two buses

    Question: Equations: My solution: Could someone verify my answer?
  38. A

    Voltage Drop in Parallel Receptacle Wiring

    I know how to solve the question but I am a bit confused about why there is a current of 3 A and a voltage of 110 V requirement for the refrigerator but the power plant only supplies 110 V. How can there be a voltage drop on the refrigerator load of 110 V, when there is also a voltage drop on...
  39. C

    Radio Power Conversion: Convert mV/m or nW/m2 to Watts

    I have searched the internet and spoken to the manufacturer of my equipment and can not find an answer. I am using RFExplorer (test equipment) to measure the power generated by my ham radio antenna. The only options for displayed power is mV/m or nW/m2. I am trying to find out how to convert...
  40. fsonnichsen

    I Calculating Candela Power for LED

    I am looking for the power in watts, total, put out by and LED. This for example, if I enclosed the complete device in an integrating sphere, what power output would be measured in watts. Unfortunately a lot of the vendors report power in Candela. I could not get a response on this, but I am now...
  41. bluesteels

    AC circuit power formula question

    im kinda confused on why can't you just use the formula P=I^2R. Can you just use Vrms or Vamp (not sure which one is it) and the value of R which is 105Ω to solve for I Then just plug it in the formula P=I^2R. But when i did that it the wrong answer so is this formula don't work for AC...
  42. C

    Power required to climb a 20-m-tall building in 55s

    Summary:: A 90 kg firefighter needs to climb the stairs of a 20-m-tall building while carrying 40kg of gear. How much power does he need to reach the top of the building in 55s. So first the total mass of our system is 130 kg. Using this mass, I found the potential energy the firefighter would...
  43. A

    I Power equation in railgun operation

    In a capacitor discharge through a plain resistor, the capacitor power supplied at any instant is VI; the power dissipated in the resistor is I²R. So VI = I²R. Consider a railgun operated with a capacitor bank. At any instant of capacitor discharge, the power supplied is VI. The total power...
  44. A

    Audio/Video Please help, require schematic diagram of power amplifier ROYAL L1200

    Hi to all much appreciation for you all,please is there anyone who can help me the schematic diagram of power amplifier ROYAL L1200
  45. F

    Engineering Find the reactive power before power factor correction

    Relevant Equations: My solution: Could someone please verify my answer?
  46. Joshy

    Engineering Source impedance using given voltage swing and power

    Hi! I normally have a pretty good grasp of what the source and load impedance for these types of problems; however: This textbook is giving me peak to peak voltage swing 6V33 and 1 W of power. I'm a little bit confused at converting this into an input impedance and am worried I'll be off by a...
  47. Kamuna

    Engineering Understanding Rankine Cycle Pressures: Should P2 Equal P3?

    Is this the right path in solving this problem? Am i finding the correct enthalpies? I am also having difficulty understanding so what I've understood is that in a rankine cycle P2=P3 but here P2 is given and P3 has a given variable which is T=25 C too so should I neglect P2=P3? Heres my...
  48. G

    I Interpreting Thermal Power in Cylinder with Source & Sink

    I have a cylinder that is separated with an insulator. In the internal cylinder there is a thermal source, while outside the insulator we have a thermal sink. The power of the internal cylinder is positive, while of the external one in total is negative. How I should interpet the results. Like...
  49. A

    Engineering How to calculate the power distribution through this gearbox?

    Greeting! My problem is to understand the flux of power inside this gearbox for example I can´t understand why the power in load 2 and load 1 are not equal to the power of the motor (suppose 100% efficiency). if this gearbox was an energy circuit (how to know that the energy is transmitted and...
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