Is there a government agency that specifies and enforces the voltage and frequency, and tolerances? Or is 120V just a defacto standard that most utilities adhere to? And what about the allowable range?
For product design I use a lopsided tolerance- 120V +10/-20% minimum for example, preferably +15%/-30% or more under most conditions, especially for dips of < 1 second. I don't like marginal tolerance to line voltage that results in dropping out or resetting when motors on the same circuit start etc.
Best regards, Spehro Pefhany
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AFAIK there is no "official" standard and apparently never was one, per se. 40 or so years ago, "everyone" called it 110VAC and later called it
115VAC, and the common nomenclature is either 115VAC or 120VAC depending who you alk to. I clearly remember tube radios designed to run on 110VAC after 10 years(?) then having failures stemming from higher line voltage. And now, i see that the line voltage is commonly 120VAC to 125VAC, which clearly wastes energy and is un-necessary. Remember, power increases as the square of the voltage.
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| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
It\'s what you learn, after you know it all, that counts.
What makes you say that? In something with a switching power supply, there'll be less current drawn and hence efficiency will actually improve a skosh thereby saving energy.
As for it being unnecessary... well... compared to what? Much of the rest of the world thinks that 220V-240V is the way to go... Japan thinks 100V is where it's at (at least that's a nice round number!)... etc...
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |
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| 1962 | It's what you learn, after you know it all, that counts.
The lamps won't last long enough to care about ( if incandescent ). Who in their right mind would use incandescent much these days anyway ? You obviously do know it's a trade off between efficiency and lifetime and are just being silly minded over lamps.
As for motors. Who wound them for 115V in the first place ?
Fluorescents don't have the same light output when retro-fitted.
The A/C manufacturer.
...Jim Thompson
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| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
It\'s what you learn, after you know it all, that counts.
It has been generally considered that household AC line voltage is at its specified voltage at the "service entrance" or at the breaker box.
Plenty of equipment was designed to work optimally or work closest-to-specifications at at a slightly lower voltage that anticipates voltage drop in wiring downstream of the breaker box.
Also, I have heard enough to build quite an impression that the "USA-typical" household AC voltage (when delivered to appliances) has increased slightly over the decades. As in 117 in the mid-late 1950's and the 1960's, 115 in the earlier postwar times, 110 in the earlier years of widespread home electrification, and 120V in the 1980's with shiploads of anecdotes of more like 125V from the late 1980's to now.
Motors also have to work both in "normal conditions" and in times of slightly reduced line voltage.
High current draw motors, such as air conditioner motors, have to be optimized for typical voltage drop in a typical residential circuit. Given high current draw of air conditioners designed to work on 120V AC circuits, I consider it reasonable to optimize them for 115 VAC.
Keep in mind that I have heard enough of "good practice guidelines" (it may be code) to design household wiring to have a voltage drop no more than 5% "full current" (which is typically 20 amps for new work with 12 gauge wire, mainly around and after the 1070's, and 15 amps for 14 gauge wire, which was mainly well before the 1970's - ROUGHLY!).
Time to cut back on the wine so you can read the labels. Bulbs come in 120 & 130 volt versions, and I haven't seen a new motor marked 115 volts in over a decade.
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Michael A. Terrell
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This is true only for linear loads, such as heaters, and if they are on a thermostat, they will just heat the room (or water) faster, and be off longer. Incandescent lamps increase resistance as they run hotter and produce more light, so you might get by with a 60W lamp instead of a 75W if you use a higher voltage and just compare lumens. Fluorescent lamps are limited in current by the ballast and their specific characteristics, and modern energy saving systems compensate for line voltage. I believe the new LED lamps are also current regulated.
Motors tend to draw the amount of power they need, so they will draw more current at lower voltage to do the same work, and run less efficiently due to line drop. You will probably burn out a motor faster on low line voltage than high, within reason. Also, many motors are designed for 50/60 Hz, so that provides about 15% higher allowable voltage at 60 Hz before you will get overheating due to saturation at the voltage peaks.
New appliances are being designed that use 3 phase motors and inexpensive VF converters, which rectify the line voltage and then synthesize the correct voltage and frequency for most efficient operation at variable speeds. Computers and other electronics gear use switching supplies which draw less current at higher voltage, so there is less line drop and greater efficiency. If it is a severe and persistent problem, a simple bucking autotransformer can correct the voltage by subtracting 6, 8, 12, or 16 volts.
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