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. H

    Timer based switch for a power capacitor

    To cover transformer loss at no load and maintain pf, we are needing 6kvar at day time and 9 kvar at evening. Is there any time based switch available, such that it can switch ON 3 kvar at evening, say 8:00pm and turn off automatically at 8:00AM morning
  2. M

    How is it possible to use only 1000 W to transfer 10,000 BTU/h?

    Hi, I was reading a newspaper article on the energy efficiency of commonly used air conditioners in homes. Then a doubt arose when the article informed me that there are air conditioners that have an energy efficiency of 10 BTU/watt. That means a classic 10,000 BTU/h air conditioning machine...
  3. G

    Automotive How much power is needed to haul a weight up an incline at a certain speed

    Good afternoon everyone, I need help with a certain calculation. How much power is needed to pull a 250lb load up a 45 degree incline at 5 mph. I am working on a project at school and would like to know what kind of motor we can use. Thank you very much!
  4. N

    Could Radioisotope Thermoelectric generators power electric cars?

    Could electric cars be given longer range by radioisotope thermoelectric generators like they use to power spacecraft in deep space?
  5. F

    Query about the time average of an AC power supply

    Hi there, I have a query about electric power in AC systems. I am Chilean, and over here the power supply is 220 V (rms) at 50 Hz. Some countries use voltages in the range 200-230, but others use 110 V or so, at frequencies of 60 Hz. There is no uniqueness, but all work. My question is...
  6. Pushoam

    Power being transported down the cable

    Relevant equation: Since the potential difference V is independent of time and current I is steady, both the electric field and magnetic field are independent of time. Hence, the first term of R.H.S. of (8.9) is 0. If V >0, then ## V_{in} - V_{out} ## = V, ## \Rightarrow...
  7. J

    Intensity of sound, power output

    I is proportionate to E. r = 4.3xxm So I put 0.75I The answer is 49mW.. But I got 97.xxmW What is wrong?
  8. D

    Electrical How to build a DIY laser power meter

    How do I build diy laser power meter. I tried shining 5 milliwatt laser on photodiode. Photodiode is connected to led. Led never turned on.
  9. B

    Intensity and power question (weird)

    https://pmt.physicsandmathstutor.com/download/Physics/A-level/Past-Papers/AQA-Old/Unit-5/June%202016%20MS%20-%20Unit%205-2A%20AQA%20Physics%20A-level.pdf One question on this the mark scheme seems to skip this step as the intensity is Power per unit area , when you make I sun = I quaser *...
  10. DaveC426913

    Appliances Faulty DeWalt Battery charger for power tools

    I've replaced the charger for my DeWalt tools several times, and now I may have to go out and get a fourth one. One of them flashes a fault warning (steady slow flash), the other two do not light up at all. Now, I do not take care of my tools. All three of these chargers may have been exposed...
  11. K

    Electrical Help with making a heating element with a 3 phase power supply

    hi everyone. my uncle currently has a big "cylindrical rolling cooking pot" (imagine a cement mixer with burners at the bottom) that he uses to cook his stuff, ie sesame seeds. this cooking pot currently runs on gas. as he has been facing some issues with the gas supplier, he intends to...
  12. B

    Power dissipation question I^2 R

    I understand that when using the equation I^2 * R that current is meant to be constant in each component? I got the idea from this video So how can we use this equation to find the relationship between varying current against power? As the current is at a constant?...
  13. A

    RF cavity shunt impedance, PD and input power

    I still did not understand this from my previous threads, what is the way to determine the instantaneous voltage across the cavity plates at any given moment, in a klystron I suppose the voltage would be proportional to the arriving electron bunch density which would determine the overall bunch...
  14. E

    Comparing RBE to relative penetrating power?

    Relative biological effectiveness is a factor that radiation dose is multiplied by to account for differences in biological damage by varying types of radiation. RBE is higher for alpha particles than any other, yet the relative penetrating power of alpha radiation is the smallest of the four...
  15. A

    Core material for high power high frequency coil/solenoid

    I read the limits of typical ferrite cores and it seems that most sources claim that they tend to work somewhere up to 1 Mhz. Surely they work great under that frequency, but is there any material that could provide a core material for a wide frequency range starting from few tens of Khz up to...
  16. M

    Power to drive rollers in a machine

    Hi, I've attempted to solve the first part (see file Position 1) in mathcad, but have no idea if it's correct, at least for the first part, as I am assuming, that the steps will be the same for the rollers in the remaining positions. So if I can manage to calculate the first one correctly, I...
  17. J

    Why don't birds get shocked on power lines?

    I know the answer, because they are not grounded and do not complete any circut, but I have a different analysis that I would like to explore. First, why do you need a closed circuit? Because if you have a battery pushing current along a wire that ends, electrons will accumulate at the end of...
  18. Electgineer

    Find the power supplied by the 1V source in the circuit using nodal analysis

    My attempt: At node 1 > 4 = 6 + I1 Node 2 > I1 + I2 = I 2 Node 3 > 6 = I 3 + I 4 I1 = (V1 - 4)/21 In node 1, Using the equation for I1, V1 = -38V. I2 = (V1 - 4 - 1)/2 So, I2 = -21.5APower supplied by the 1V battery is P=VI P=-21.5 x 1 P=-21.5W I am not sure of my method, I just started...
  19. anorlunda

    Insights When Renewable Energy Meets Power Grid Operations

    Continue reading...
  20. T

    Is 1800 Newton meters enough torque to generate 1.5 kilowatts of power?

    i am working on new project so i could use your help. Please and Thank you Tony
  21. EEristavi

    Why a DC power supply doesn't have a voltage with respect to ground?

    I see that DC power supply have voltage between it's + & - and its 24V. However, there is no voltage with ground. I don't understand - if device's "point" has some potential, why doesn't it give some voltage with ground (which has ~0 potential) I tried this with phoenix contact...
  22. Zeynaz

    How Many Square Meters of Solar Panels Are Needed for Household Usage?

    First, I calculated the power generated by the solar panel in one day. So since the intensity is 1.0e3 watts per 1 m2. 10% of this peak power is utilized so (1000)(0.10)=P-utilized=100W (per 1 m2) the solar panel has the efficiency of 13% so of this power only 13% is useful. P-useful=...
  23. Mahathir

    Calculating Sound Power: I=P/A & Dependency on Area

    Is there any formula for calculating sound power? What does the A mean in I=P/A? Is the power of sound dependent on the area of its surrounding or something. I want to know if there's an equation for P like there's I=2π²a²f²ρv.
  24. Chandrakanth_balusa

    Estimation of the Power Output of a steam turbine

    Hoow can one estimate the amount of steam required to generate certain amount of electical power mathematicaly?
  25. DrClaude

    Power lines connecting to the ground

    This is going to be a very basic question, but something that has bothered me for a while. It was triggered again by this thread from @OmCheeto: https://www.physicsforums.com/threads/new-deccan-trap-turns-out-to-be-downed-power-line.970313/ Why is it that when a power line is downed, there is...
  26. OmCheeto

    New Deccan Trap turns out to be downed power line

    A link to this video popped up on my Twitter feed this morning: link The person who posted it asked for guesses as to what it was. I guessed; "Baby Deccan Traps?". She said "No." Then she posted the explanation: Maharashtra: Panic of volcanic lava trigerred after Beed locals witness rocks...
  27. I

    Jackson E&M: Power loss in waveguides for TE & TM modes

    Hi. I'm having trouble with calculating (8.59) from (8.58) (## \vec H_{//} ## is simply ## \vec H ## in Jackson, but that shouldn't matter.) in Jackson. Specifically I think I'm not sure about parallel component of H field here. For example, shouldn't I have two terms for the...
  28. Marco Masi

    How much excess energy goes lost in solar and wind power stations?

    Since solar and wind power are fluctuating energy sources not all of it goes into the grid when the consumer power demand is lower than that actually produced. This is a well-known drawback of solar and wind energy that everyone talks about. What I never found is an assessment of how much of the...
  29. A

    How to calculate mechanic power a person outputs?

    Hey all, I am doing some work to brush up my acoustics and one of the problems I came across this goes like this (translated, so sorry for potential grammar mistakes although I'll do my best to avoid them): A singer exhales 0.1 Litre Air per second. The 'overpressure' (pressure difference, so...
  30. J

    MHB Power Series for f(x) and Radius of Convergence

    f(x) = 4x/(x-3)^2 Find the first five non-zero terms of power series representation centered at x = 0. Also find the radius of convergence.
  31. reddvoid

    What is AP layer in Ansys RedHawk?

    What is AP layer in ansys redhawk ? I have list of layers I see in ansys redhawk tool, there are different metal and via layers , instances etc and there is a layer called AP in the end, What is this layer or where can I find more information bout it?
  32. Miles123K

    Force and power applied to create a traveling wave

    Again I am really confused, but I just put the traveling wave as: ##\psi(x,t) = Dcos(kx- \omega t)## for positive x ##\psi(x,t) = Dcos(kx+ \omega t)## for positive x Then I simply differentiated and plugged in ##x=0## ##F(t) = - T D k sin(\omega t)## and from this ## \langle P \rangle = T D^2 k...
  33. TheBigDig

    Efficiency of a steam power plant

    My inital assumption was to just take T1 = 5600 and T2= 300K, find the maximum efficiency and then divide it by two and three but I don't believe this question to be that simple. I'm confused as to where the 750K fits in as I thought no matter what occurred in between the heat reservoir and heat...
  34. H

    Find an expression for the power developed at the given rotation rate

    So for part (a), I used the fact that 1/N = the period = T. I solved for the velocity, where i got v=2πRN. I plugged that v into F=(m v^2)/R, which is the centripetal force, but also the force of friction. My answer to part (a) is 4(π^2)mR(N^2). I'm a bit confused on part (b). I know that...
  35. noxidINF

    Motor drive a coil in a magnetic field to power itself?

    Hello Friends, I have been wondering, is it possible to construct a motor, and attach a coil to it, such that with the motion due to the rotation of the motor, it generates a excess of energy that can be used to power the motor in turn, basically, could i use the excess to charge a battery that...
  36. BWV

    Solar power: a looming environmental disaster?

    Had not seen much discussion of this, but of course PV cells are semiconductors with a finite life and will have to be disposed of within a decade or two https://www.scmp.com/news/china/society/article/2104162/chinas-ageing-solar-panels-are-going-be-big-environmental-problem
  37. M

    What is the power input of a motor pulling up an elevator?

    Homework Statement Once under way at a steady speed, the 1100-kg elevator A rises at the rate of 1 story (2.74 m) per second. Determine the power input Pin into the motor unit M if the combined mechanical and electrical efficiency of the system is e = 0.76. Here is a link to the diagram for...
  38. M

    Torque required to tilt 1200 kg mass?

    Object to be tilted = 1200mm diameter cylinder Cylinder height = 2.5 meter weight of tilting assembly = 1200 kg Cylinder is on platform which is "L" shaped and tilting point is on that corner of "L" as in attached image. Shaft diameter on which it is tilted id 63mm Angular acceleration = 0.05236...
  39. T

    PCB design and schematic for a half bridge power amplifier

    Hi, I am making a half bridge power amplifier that operates at 24 V. The bridge has to supply around 3A current to an inductive load (10mH) The bridge will be controlled using 20kHz PWM from a microcontroller. I have put a ACS712 current sensor in the load path to give feedaback to the...
  40. M

    What should I consider when searching for a high voltage power supply?

    I'm looking for a high voltage power supply. I have no experience with such a power supply, nor with all the terms or specifications used for such tools, so I'm looking for general suggestions to what to look for. I want to generate an electric field or potential field between two points a few...
  41. N

    China's Experimental Advanced Superconducting Tokamak (EAST)

    A team of scientists from China's Institute of Plasma Physics announced this week that plasma in its Experimental Advanced Superconducting Tokamak (EAST) would be ready to begin attempting to generate more energy than it uses, in a world first. I am dubious about more news that comes out of...
  42. F

    Alternative for lithium in Deuterium-Tritium fusion power

    Is there alternative ways for producing Tritium for fusion power plants other than using lithium?. In the wiki article about fusion power I read that Deuterium-Deuterium fusion produce Tritium so I wonder if this can be used as a way to produce tritium for Deuterium-Tritium fusion power plants...
  43. C

    Offshore wind power without subsidy

    News: The cost of offshore wind plant has been falling rapidly and now some projects in Holland are viable without subsidy... https://www.offshorewind.biz/2019/03/13/dutch-powerhouses-reveal-zero-subsidy-offshore-wind-play/
  44. T

    Power output of a theoretical generator

    so, assuming that you know all of the aspects of your theoretical generator, apart from the voltage and current, how would you work it out. I know that it is possible, but i can't find anything that I understand, or is even valid online. There should be some equations i can use to work it all...
  45. N

    Deriving Voltage from the Inductor Equation

    Homework Statement L = 20mH = 20 x 10-3 H i = 40 mA for t≤0 i = A1e-10,000t + A2e-40,000t A for t≥0 The voltage at t=0 is 28 V. I have to find the equation for the voltage for t>0. Then I have to find the time when power is zero. Homework Equations v(t) = L* di/dt p(t) = L*i* di/dt The...
  46. R

    Automotive How Can I Calculate the Minimum Value of n2 in Tractor Power Transmission?

    Hi, I have a problem to design traktor power transmission.Can anybody tell me How to calculate minimum speed for output shaft.I need to calculate number of rotation(maximum and minimum) of the driven shaft Here is the equation: n(driven) max=(n(drive) + n2 (max). (z3/z1)) /(z3/z2 +1) so I get...
  47. P

    Unbalanced 3 phase power - what happens without a neutral wire?

    Hi I've recently started learning about electrical three phase theory, and therefore got some questions. Imagine the following: Countries like Albania, Norway ++, have IT earthing configuration in their distribution grids, i.e. the neutral point is not solidly grounded, however "grounded"...
  48. Akash47

    Calculating Pump Power for Well Water Removal

    Homework Statement A well has a diameter of 6 m and a height of 15 m.2/3 of volume of the well is filled with water.A pump can vacate 1/3 of volume of water from the well in 7 minutes 20 seconds.What is the power of the pump? Homework Equations W=mgh, P=W/t The Attempt at a Solution The...
  49. H

    How can I calculate the number of photons with this data?

    The problem says: A radio station emits electromagnetic wave with a frequency of 100MHz (102*106 Hz). a)What's the energy of this radiation's/glow's photon? (Solved, i found 6,63*10-26 J) b)Compare your calculation with the energy of another visible radiation/glow, with a wavelength of 600nm...
  50. TechTree

    Share a power supply between two devices

    Hello, I have recently converted an old bluetooth speaker into a Aux input device for a guitar amplifier. You can see how I converted it here. So now I'm trying to power both the bluetooth device and the guitar amplifier using the original amplifier's power supply. Here is the power that each...
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