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Questions tagged [power]

152 questions
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4 answers

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 gone forever. (Except saving money on bills) My…
ShivCK
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Why does it take so long to restart a nuclear power plant?

I have heard a couple of times that an operating nuclear power plant which was shut down (non-emergency; e.g. for a regular check) needs over 24 hours (up to 72 hours?) to get up running again. Why does it take that long?
Martin Thoma
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How to calculate Power of motor when used as a generator?

How can you calculate how much power can be generated by a motor when used as a generator (like a motor used in a wind turbine)? Does the power depend on how fast the magnet is rotated? If so, is there a equation that lets you know given the rpm,…
user510
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Does a transformer use power when output isn't under load?

I was reading about how AC to DC converters work with a step-down transformer and then a diode bridge to convert the lower, stepped down AC voltage into DC. What I don't understand is since the input AC appears to be connected to the primary coil of…
jhabbott
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What is the difference between Bluetooth Low Energy and Bluetooth BR/EDR in Park mode?

It is known that Bluetooth Low Energy transmits data only during short time intervals called Connection Events. Connection events occur regullary with predefined period. The rest of the time Bluetooth LE device is does not transmit nor receive data.…
user1558573
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Why do hydroelectric plants use turbines instead of an efficient 'water wheel' configuration?

I have been thinking about hydroelectric plants and I have been wondering why they are built the way they are. As in understand it, a stream of water is sprayed at a turbine, located at the bottom of a dam (Pelton Turbine.) This does not seem to…
Hoytman
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How to apply power flow analysis?

I have an (AC) power grid topology with generators, consumers, power lines, tranformers, etc. I also have a "snapshot" of the system's state, i.e., I know how much real power the generators feed, how much real power is used by the consumers, I know…
Technaton
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What needs to be considered when configuring the clock system for a MSP430F5xxx micro-controller?

I need to configure the clock systems for a MSP430F5528 microcontroller. The current development board has a 24MHZ crystal attach to XT2 pins (XT2IN/XT2OUT). The current design will need to support the follow peripherals. UART ADC SPI Timers Few…
Mahendra Gunawardena
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How can I calculate the temperature rise of a circuit board for a given power dissipation and area?

I have a PCB of approximately 4" x 4". It has a single long spiraling trace on it. The trace is 50 mil 4 oz copper, so nominally it's good for something like twenty amps before it overheats. But this board overheats much faster. My supposition is…
Stephen Collings
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Having three heaters on single PCB

I posted this question on electronics SE, but was suggested that I post it here. I basically having three heaters (serpentine pattern) on a PCB (fiberglass board), as the following image shows: The ones at the end would be heated to 95°C, the ones…
Koushik S
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Third Rail vs Overhead Cable: which is more efficient in terms of electricity consumption?

I'm well aware that there are many different factors to be considered, such as ease of installation/maintenance, conversion from AC to DC, environment, distance, speed, frequency of turns, and so forth. Setting all of those aside for now, suppose we…
Ricky
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3 answers

Relationship between wind velocity, turbine rotor diameter, and power output

I'm trying to understand and identify the equations to use in defining the relationship between wind velocity, turbine rotor diameter, and power output for a wind turbine. To simplify my question, let's use the following assumptions: Average wind…
Dwiparna Datta
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Alcohol as a working fluid?

Alcohols with their lower boiling point and overall non-toxicity, could they be used as a turbine working fluid instead of steam water?
LazyReader
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How to select a micro controller for a low power applications?

I am interested in a microcontroller for a low power application. I have been advise to look at MSP430 or Microchip PIC microcontrollers. I also wonder if ARM-Cortex-M0 is a good choice too. At a high level the system will have two analog sensors,…
706Astor
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Mathematical expression for power loss in a dielectric

I am trying to prove the equation $$ \frac{\bar{P}}{V}=\frac{1}{2}E_0^2\sigma_{AC} $$ which can be rewritten as $$ \begin{align} \frac{\bar{P}}{V} &= \frac{1}{2}E_0^2\sigma_{AC}\\ &=\frac{1}{2}E_0^2\ \omega\ \epsilon_0\ \epsilon^{''}_r\\ …
Quaker
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