AC Voltage Source: Meaning of 50/60º RMS & Peek Voltage

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Discussion Overview

The discussion centers around the meaning of AC voltage specifications, particularly the significance of 50/60 Hz and the relationship between RMS and peak voltage. It encompasses theoretical explanations and practical implications in electrical engineering and household applications.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about the meaning of 50/60º in relation to AC voltage sources, noting that their study material mentions RMS and peak voltage.
  • Another participant explains that AC voltages are typically expressed as RMS values and that the frequency varies by region, with common standards being 60 Hz in North America and 50 Hz in many other countries.
  • A third participant elaborates on the nature of AC waveforms, emphasizing that the power delivered is an average over the entire cycle and that RMS values are derived from integrating the voltage over time.
  • One participant points out that while frequency may not significantly impact many AC circuits, it can be critical in transformer applications, where using the incorrect frequency can lead to magnetic saturation of the core.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the implications of frequency on AC circuits, particularly in relation to transformers. There is no consensus on the importance of frequency in all contexts, indicating a mix of agreement and disagreement.

Contextual Notes

Some assumptions about the relationship between RMS and peak voltage are made, but the discussion does not resolve the implications of using different frequencies in specific applications.

Who May Find This Useful

This discussion may be of interest to students studying electrical engineering, professionals working with AC circuits, and individuals seeking to understand household electrical standards.

travelalfred
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What does it mean when you put on a AC voltage source (~) 50/60º.
The book I've been studying from says the rms or peek voltage only.
Thanks.
 
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AC voltages are usually given as the RMS voltage and the frequency.

The household supply varies with different countries, but most fall into the 100-120 volt 60 Hz frequency group (North America, Japan), or the 230-240 volt 50 Hz group.

The supply is always a sinewave and the RMS value is the peak value divided by 1.414.

This site:
http://en.wikipedia.org/wiki/Mains_power_around_the_world
gives an interesting look at the mess of voltages and plugs around the world.

50 Hz / 60 Hz means that either 50 Hz or 60 Hz is OK.
 
An AC waveform, at least from the mains, is sinusoidal. The power delivered is an average over the whole cycle of Voltage, which goes from + peak, through zero, to a - peak. The average value of Voltage is zero - which doesn't tell you much about the peak values. To work out the 'effective' Voltage to get power delivered to a load, you need to add up (integrate) the energy delivered at all stages in the waveform.
One formula for power is P =V2/R.
If you average this over the whole cycle for all instantaneous values of V and average it, you get the 'mean square' value of the Power. Rearranging and taking the square root of this gives the 'Root Mean Square' (RMS) value of the varying Voltage. For a sinusoid, the RMS value is the peak Voltage/(Root 2). The relationship is different for other shapes of waveform.
This RMS Voltage produces the same power from a resistor (lamp / heater etc.) as a DC Voltage of the same value.
 
For many AC circuits, whether the frequency is 50 or 60 Hz is of little consequence. But in circuits that have transformers, use of 50 Hz AC power in a transformer designed for 60 Hz at the same voltage will exceed the volt-seconds of the iron core and drive it into magnetic saturation.

Bob S
 

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