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Nile Anderson
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When I am calculating the power in the circuit , do I use the RMS values , or the peak values and why ?
Which Values Should I Use When Calculating Power in a Circuit?
- Thread starter Nile Anderson
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In summary, When calculating power in an electrical circuit, you can use either the RMS values or the peak values, depending on the specific circuit and its components. The RMS values are generally considered standard and accurate enough for most purposes, but if the circuit has significant reactive elements or is not close to a sinusoidal waveform, the peak values may be more relevant. However, the 1/√2 figure commonly used for working out RMS power assumes a sine wave and a pure resistance, so it may not be perfectly accurate for other waveforms or non-ohmic loads. Ultimately, the choice of which values to use depends on the specific situation and what information is needed.
- #2
NascentOxygen
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RMS values are standard.
- #3
Nile Anderson
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Thank you !
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sophiecentaur
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I may be being difficult but what circuit and where is the value of the power, relevant? The peak power in a circuit with significant reactive elements in it could be very relevant - particularly if the waveform is not close to a sinusoid. RMS is certainly near enough for Jazz in most cases.Nile Anderson said:
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Nile Anderson
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Sorry , it would be sinusoidal in nature. What did you mean by enough for jazz though ?sophiecentaur said:
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sophiecentaur
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"Near enough for Jazz" is a common expression which means 'accurate enough for the purpose'. When you read an unfamiliar idiom, Google is almost certain to help you with it. There a dozens of hits for "near enough for jazz".Nile Anderson said:
Measuring Power in an electrical circuit has a few issues. If you really want to know the power being dissipated in a component (Resistor,light bulb, LED, motor - you name it) you need to know both the instantaneous Volts and the Current. Then the Mean power for any component is the average value of VI, over a given time. That involves no assumptions and involves measurements of two quantities. If the component is pure Ohmic resistance then you can use
Instantaneous Power = V2/R or I2R and use either just V or I.
To find the average power - say over a cycle or an hour, you average all those instantaneous values of power. The 1/√2 figure that people use for working out RMS power from Peak Volts (for instance) definitely assumes a sine wave and a pure resistance and would not work perfectly for any other waveforms or non ohmic loads.
So "you pays your money and you takes your pick"
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Nile Anderson
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Cool thank you so much for your input , it was really helpfulsophiecentaur said:"Near enough for Jazz" is a common expression which means 'accurate enough for the purpose'. When you read an unfamiliar idiom, Google is almost certain to help you with it. There a dozens of hits for "near enough for jazz".
Measuring Power in an electrical circuit has a few issues. If you really want to know the power being dissipated in a component (Resistor,light bulb, LED, motor - you name it) you need to know both the instantaneous Volts and the Current. Then the Mean power for any component is the average value of VI, over a given time. That involves no assumptions and involves measurements of two quantities. If the component is pure Ohmic resistance then you can use
Instantaneous Power = V2/R or I2R and use either just V or I.
To find the average power - say over a cycle or an hour, you average all those instantaneous values of power. The 1/√2 figure that people use for working out RMS power from Peak Volts (for instance) definitely assumes a sine wave and a pure resistance and would not work perfectly for any other waveforms or non ohmic loads.
So "you pays your money and you takes your pick"
What is reactive power?
Reactive power, also known as imaginary power, is the portion of electrical power that does not perform any actual work but is required to create and maintain an electromagnetic field. It is measured in units of volt-amperes reactive (VAR) and is necessary for the operation of inductive components such as motors and transformers.
What is active power?
Active power, also known as real power, is the portion of electrical power that does perform actual work and is measured in units of watts (W). It is the power that is used to run electrical devices and is typically what is billed by utility companies.
What is the difference between reactive and active power?
The main difference between reactive and active power is that reactive power does not perform any actual work, while active power does. Reactive power is necessary for the operation of inductive components, while active power is used to run electrical devices and is what is billed by utility companies.
Why is reactive power important?
Reactive power is important because it is necessary for the operation of inductive components such as motors and transformers. Without reactive power, these components would not be able to function properly and could potentially be damaged. It also helps to maintain a stable voltage and current in an electrical system.
How is reactive power compensated for?
Reactive power can be compensated for by using devices such as capacitors and inductors, which can store and release energy to balance out the reactive power in an electrical system. These devices are often used in power factor correction systems to improve the efficiency and stability of an electrical system.
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