What is Power: Definition and 999 Discussions

A power outage (also called a power cut, a power out, a power blackout, a power failure, a power loss, or a blackout) is the loss of the electrical power network supply to an end user.There are many causes of power failures in an electricity network. Examples of these causes include faults at power stations, damage to electric transmission lines, substations or other parts of the distribution system, a short circuit, cascading failure, fuse or circuit breaker operation.
Power failures are particularly critical at sites where the environment and public safety are at risk. Institutions such as hospitals, sewage treatment plants, and mines will usually have backup power sources such as standby generators, which will automatically start up when electrical power is lost. Other critical systems, such as telecommunication, are also required to have emergency power. The battery room of a telephone exchange usually has arrays of lead–acid batteries for backup and also a socket for connecting a generator during extended periods of outage.

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  1. jasmin_89

    Calculating Minimum Power for Perception of Radiation from a Point Source

    Hallo, can anybody help me and check if i have the right result: What is the minimum power P that a point source of radiation (I=8*10^(-7) W/m^2) at a distance of l=10 m from the listener must have in order to still be perceived? (Note: The emitted energy per area can be related to a spherical...
  2. A

    Power required to reach X velocity in X time with drag

    Hello, I wrote a program that adds force to a car like so: Engine Force = Power / Velocity Drag Force = -Velocity² Net Force = Engine Force - Drag Force = Power / Velocity - Velocity² I'd like to determine power based on how fast I want a car of a given mass to reach a given speed, for...
  3. samstergurl

    Concentric coils for power generation

    Most generators work by rotating a coil within a magnetic field. This induces a current in the coil and can be harnessed as electricity. I was wondering if it would be possible to generate more power by using more than one coil with each one being progressively larger wrapped around the others...
  4. B

    Engineering RLC Series Network: Impedance, Current, Power Factor, Phasor Diagram

    Hello. I have completed the following question. My answer: i) Circuit Impedance Reactance = XL = 2 x pi x F x L = 2 x pi x 50 x 0.15 = 47.12 Ohms Reactance of Capacitor = XC = 1/2 x pi x F x C...
  5. M

    I Power Broadening: Explained & Resources

    Hello! I have seen mentioned in several papers the concept of power broadening, which (if I understand it right) means that the linewidth of a transition (say, in an atom) get wider with increasing the power of the laser used (even if the linewidth of the laser is kept constant). I am not...
  6. Russ Edmonds

    Power absorbed and B vs H plot for microwave oven transformer

    A DI-149 data acquisition module was used to record a microwave oven transformer (MOT) primary voltage and current time histories. The secondary of the MOT was open. The DI-149 analog input specs are: +- 10 volts full scale, 5000 samples per second for each channel (assuming two channels being...
  7. andyskin

    A 50 kW load operates from a 60 Hz 10 kV rms line with a power factor of 60% lagging -- Determine the capacitance that must be placed in parallel

    Please can you have a look at the file at point me in the right direction if I'm wrong. Thank you
  8. C

    MHB Finding a formula for the multiplication of multiple formal power series

    Dear Everyone, I am having trouble with finding a formula of the multiplication 3 formula power series. \[ \left(\sum_{n=0}^{\infty} a_nx^n \right)\left(\sum_{k=0}^{\infty} b_kx^k \right)\left(\sum_{m=0}^{\infty} c_mx^m \right) \] Work: For the constant term: $a_0b_0c_0$ For The linear...
  9. cheekyhouidini

    Mass of water given only power and density

    Cannot figure out where to start, apart from maybe something to do with specific heat capacity of water?
  10. coreanphysicsstudent

    Rational power of the imaginary unit

    but the real answer is −1, (1±i√3)/2 What's wrong with my solution? please help me through.
  11. E

    Create a method to measure a varying voltage from a power line

    I feel like i am spinning my wheels at the start here. so I figured that i would start with some type of wire loop that I could change its diameter. This would allow there to be a change in flux through the loop creating a current through the wire. i could then read the current through the...
  12. F

    EMF below Power Transmission Lines

    Many years ago I was responsible for maintaining the integrity of a buried fiber optic cable that utilized a railroad right-of-way. Kinda like watching submarine races ! Along much of this routing, transmission towers / power lines would be adjacent to the railroad. Talking with railroad...
  13. M

    How to calculate the efficiency of a switch mode power supply?

    I know how to calculate the power output and input by analyzing the current in put and output with multimeters and using the formula P=VI. But P_out is obviously incomparably smaller than P_in so the efficiency would suck this way. Is there a better way to do this??
  14. S

    Refrigerant - mass flow, power, COP

    This is a past exam Q, I don't have the attached pressure enthalpy diagram. Q = 120kW Cp = Refrigerant enthalpy = I've looked this up, for ammonia enthalpy = 35.06 kJ / mol T2 = 5 degrees C = (5 deg C) (1100 kPa/300 kPa) = 18.33 deg C +273.15 K = 291.48 K T1 = 2 degrees C = (2 deg C)(1100...
  15. WonderfulWorld

    Calculating the Efficiency, total output power and irradiance of LEDs

    Hi Everyone, This is my first post and I hope to work with you on this to gain a fuller understanding. I'm currently designing an LED circuit with 60 3 watt LEDs. Input power is both 120VAC for North American and 230VAC for other countries. I know this is pretty basicbut what is the best way...
  16. G

    Determining the power of frictional force

    I can say that the frictional force always against the rolling sphere and the velocity is increasing for the ball. So The dot product F.v keeps on getting more and more negative, so how can the Pf remain constant? Well the velocity increases along the incline and the force of gravity is down...
  17. archaic

    Finding this power series -- Where is my error?

    I have used ##\sim## but meant ##\sum_{k=0}^\infty## my math homework platform is telling me that this is wrong. I've tried using desmos to test it and it was a perfect match. Any ideas on where I went wrong?
  18. Shubol3D

    Calculate the output power for da Vinci's tank mechanism

    Hello everyone. I'm working on 3D animation about da Vinci tank and why it doesn't work. Please help me find out how to compute: 1: how many men need to move this machine 2: what power on wheel can produce different number of man, like 1, 2, 4, 8.. vehicle mass = 8t men strength = 60kg lever...
  19. Rongeet Banerjee

    Work, Energy and Power for a Particle moving in a Potential Field

    But yet again my text says that option 4 is correct.
  20. Rongeet Banerjee

    Why does my textbook say the KE acquired by an object is m to the power zero?

    Initial velocity u=0 Let Final velocity be v Then, KE acquired by the object=1/2mv² So the answer must be option1 i.e. m¹ But my textbook says the answer is- m to the power zero.Please explain this discrepancy.
  21. Phylosopher

    I Why perturbation theory uses power series?

    I am revising perturbation theory from Griffiths introduction to quantum mechanics. Griffiths uses power series to represent the perturbation in the system due to small change in the Hamiltonian. But I see no justification for it! Other than the fact that it works. I searched on the internet a...
  22. karush

    MHB 3.4.6 limit of a power function

    Ok all I did was DesmosNot real sure how to take limit
  23. cnh1995

    Is the Indian National Power Grid in danger?

    As COVID-19 is growing exponentially worldwide, a 21-day lockdown is going on in India since 25th March. In this period, only essential services will remain open. To boost the morale of employees working in these essential services, Indian PM had asked all the citizens to show their gratitude by...
  24. AdrianRodz1

    Voltage drop in a PCB power plane

    I'm trying to maintain a spec requirement of less than 3% drop from farthest pin to closest pin from source. I'used the entire layer for copper but my oart does not require such a large pour accept to handle high current. So I'm considering there's a trade off that should meet inthe middle of...
  25. trurle

    AC-DC Power Supply Modules: Non-Isolated Topology

    In AC-DC power supply modules, having non-isolated power converter topology may result in input "Line" (hot wire) been assigned to "Vss" (lower voltage rail) at output of power supply module, and N (neutral) assigned to Vdd (upper power rail). Inside single system, this usually does not results...
  26. E

    Power To Accelerate 1000kg Elevator Cab Upward

    (a) When the cab is carrying its maximum capacity, at what rate must the motor deliver energy to get the cab up to cruising speed? My shot was finding the acceleration, a=1.5/2 = 0.75m/s2 Displacement of elevator Vf2 = vi2 + 2aΔx Δx = 1.5m Force of elevator (Since it accelerates...
  27. A

    How to calculate (pump) power to maintain a static head?

    i've this question that i can't seem to work out an answer. supposing that a (centrifuge) pump transfer an amount of energy (power) p to a column of water height h so that it maintains that as a static head. i.e. the water level in that tube is at a fixed height h due to the power transferred...
  28. FEAnalyst

    Cooling nozzle - convection power

    Hi, when modeling convective cooling in FEA one needs to define film coefficient ##h## and ambient temperature ##T_{amb}##. The software calculates convective heat flux using this data and current surface temperature ##T_s##: $$q=h(T_{s}-T_{amb})$$ However, modeling of moving cooling nozzle may...
  29. W

    Realistic Core Weight Reduction for 1000Hz Freq in 100KW DC/DC Converter

    I have a customer looking for a 100KW isolated DC/DC converter. What is a realistic transformer core weight reduction if we get 1000Hz fundamental. Assume a 60Hz core is 300 Lbs, how much smaller could a 1kHz Core be?
  30. M

    Engineering Parseval's Theorem - Average Power of the difference of functions

    Hi, So I have a quick conceptual question about Parseval's theorem in this application. In previous parts of this question, we have found the average powers of both f(t) and g(t) by integration and using the complex Fourier series respectively (not sure if this is relevant to my question)...
  31. bagasme

    Why Isn't Horsepower an SI Unit, Despite Its Popularity?

    When we talk about engines on automotive industry (cars, motorbikes, trucks, etc.), we often refer the power produced by such engines by horsepower. But when we talk about electricity, the power is measured in kilowatts. Despite the former case is highly popular, why isn't horsepower considered...
  32. V

    Find the expression for Power in circuit

    I was wondering if someone could check my answer and see if it is correct. The resistance in series is Req= R+ R= 2R The voltage across 2R is the terminal voltage V. The expression I get is: Can I also use this formula P=I^2*R? When using it I get: Current through the resistors is The...
  33. N

    Welding Machine Increases Power: Physically Impossible?

    How is it possible for a welding machine to end up creating more power than what it started with if that is physically impossible? For ex; 200 amp @ 28vdc welding machine. starts out with main voltage being 120v @ 20amps = 2400 watts then converts it to 200 amps at 28vdc which = 5,600 watts of...
  34. E

    Nuclear Power Plants - Electricity Production

    I've calculated that reaction-energy in fission of a single atom of Uranium-235 is 2.5977713481*10^-11 Joules (based off of the equation given above.) I'm assuming that PWh has to be converted into simpler units so, 2.49PWh = 2.49*10^15Wh.. afterwards I could make it into watts but I was never...
  35. K

    Calculate the current in all parts of this electric circuit

    In the circuit below, the output is 23 W across the resistor with the resistance 6 Ohm. Calculate the amount of current in all parts of the circuit as well as the polarity and EMF ε of the unknown battery. Circuit: My attempt: I get 6 unknowns with 5 equations. I don't know how to find the...
  36. F

    Possible Values of x for Convergence of Power Series

    We transform the series into a power series by a change of variable: y = √(x2+1) We have the following after substituting: ∑(2nyn/(3n+n3)) We use the ratio test: ρn = |(2n+1yn+1/(3n+1+(n+1)3)/(2nyn/(3n+n3)| = |(3n+n3)2y/(3n+1+(n+1)3)| ρ = |(3∞+∞3)2y/(3∞+1+(∞+1)3)| = |2y| |2y| < 1 |y| = 1/2...
  37. F

    Find the interval of convergence of this power series

    ∑((√(x2+1))n22/(3n+n3)) We use the ratio test: ρn = |2(3n+n3)√(x2+1)/(3n+1+(n+1)3)| ρ = |2√(x2+1)| ρ < 1 |2√(x2+1)| < 1 No "x" satisfies this expression, so I conclude the series doesn't converge for any "x". However the answer in the book says the series converges for |x| < √(5)/2. What am...
  38. J

    Work, Power and Energy assignment marked wrong somehow? :(

    All of my working out is attached with the photos, I'm struggling to do anymore as the tutor hasn't explained anything like this yet. Any help would be much appreciated
  39. M

    Engineering Power Loss Definition in a Damped Wave Equation (Skin Depth Problem}

    Hi, So the main question is: How to deal with power loss in E-M waves numerically when we are given power loss in dB's? The context is that we are dealing with the damped wave equation: \nabla ^ 2 \vec E = \mu \sigma \frac{\partial \vec E}{\partial t} + \mu \epsilon \frac{\partial ^ 2 \vec...
  40. Boltzman Oscillation

    Must a load consume the entire available current or only what it needs

    So if I have a source of 5V and 20 amp then the maximum power I can get from the source will be: $$ P_{max} = 5*20 = 100W$$ but my load can only take in 5 watts, it will blow up. But, does this have to happen or does my load only take what current it needs? My guess is that the load takes in...
  41. stipan_relix

    Engineering Voltages, currents and power between a power plant and a transformer

    This is the first part of the problem, which I solved. Now to the second part which I can't manage to find the equations I need to use. Problem: This plant is connected to a 20/0.4 kV transformer of 250 kVA power, through an XP00-A cable (4x150 mm2, IN=300 A, Z1=0.26 Ω/km). a) Calculate...
  42. AbdullahS

    Is Replacing a 25 kVAr Unit with Two 12.5 kVAr Units More Efficient?

    Hi all, The power factor correction unit for one of the buildings that I am working on needs maintenance. The service report recommends replacing the existing 25 kVAr unit with 2 x 12.5 kVAr units as "the demand on your site according to the data supplied shows us that at most there is only...
  43. O

    Calculating Power and Force in Cycling: Solving for Force in the Equation P=Fv

    OK, so I tried to relate the equation P=Fv to the given equation that Pave^2= 3(Pftp^2)/Nh. I put Nh in terms of distance to satisfy the requirement that the answer should be in terms of Pftp and distance by saying Nh = distance/Vave. I also substituted Pave with Fvage. (FVage)^2 =...
  44. fluidistic

    Compute the useable power in a simple circuit with resistive vs. reactive loads

    This is not a homework question, but I am interested to calculate the power that can be extracted to perform useful work in two similar circuits. I have been told that it should be the same but this is not what I get. Consider a voltage source as a fixed voltage source in series with an...
  45. F

    Find the Interval of Convergence of this Power Series: ∑(x^2n/(2^nn^2))

    ∑(x2n/(2nn2)) We use the ratio test: ρn = |(x2n2/(2(n+1)2)| ρ = |x2/2| ρ < 1 |x2| < 2 |x| = √(2) We investigate the endpoints: x = 2: ∑(4n/(2nn2) = ∑(2n/n2)) We use the preliminary test: limn→∞ 2n/n2 = ∞ Since the numerator is greater than the denominator. Therefore, x = 2 shouldn't be...
  46. E

    What is the optimal power variation for a cyclist on a varied race course?

    I just thought up a little problem and wondered whether anyone could advise as to how to go about it! On a flat course, suppose a cyclist might be able to maintain 300W for around an hour. This gives a total allowed energy expenditure of ##1080t \text{ kJ}##, where ##t## is measured in hours...
  47. Shubhan672

    Power series: x^3/3 + x^9/9 + x^15/15 .......

    Moved from technical forum section, so missing the homework template Let x be a real number. Find the function whose power series is represented as follows: x^3/3! + x^9/9! + x^15/15! ... I see that there is a connection to the power series expansion of e^x but am having difficulty finding...
  48. J

    Homopolar Motor: Energy Input, Output, & Magnetic Field

    I was curious in regards to a homopolar motor where the energy imparted into the rotor comes from if the energy input is say 10v at 1000 amps and there is 10v 1000amps output. Aswell if the effect of the magnetic field produces a different power on the rim of the disk vs the input from the...
  49. D

    Verify the convergence or divergence of a power series

    At the exam i had this power series but couldn't solve it ##\sum_{k=0}^\infty (-1)^\left(k+1\right) \frac {k} {log(k+1)} (2x-1)^k## i did apply the ratio test (lets put aside for the moment (2x-1)^k ) to the series ##\sum_{k=0}^\infty \frac {k} {log(k+1)}## in order to see to what this...
  50. G

    DIY nano Hydro Power generator in a Jungle

    Hi I am usually living off grid in simple huts in remote locations in Asia. A few months per year (rainy season) I don't have enough sun to produce solar power. I need very little electricity. My 20w solar panel produces enough electricity for my needs (lighting + charging a few small gadgets)...
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