[time-nuts] Line Voltage - USA
time at patoka.org
Tue Jan 3 11:05:07 EST 2017
Speaking about MAIN... I was interesting to see if "leap second" event
has correlation with MAIN frequency fluctuation
Here is graphs for the MAIN periods recorded. Note: The data on the
charts is "smoothed" by Bezier curves
I could see some "surge" which starts to climb in December 30 and end at
Dec 31 at the time close to the "leap second" event. But not sharp.
For 16-12-29 00:00 to 17-01-02 00:00
For Dec 31:
It will be interesting to see/compare if anybody else has similar stats.
On 2017-01-02 13:00, Tim Shoppa wrote:
> What modern loads are actually sensitive to high (say, +10 to +20%)
> Old incandescent light bulbs were among the most sensitive loads in the
> past (so much so, that 130V light bulbs were commonly available from
> industrial suppliers).
> I would naively expect the modern CFL's and LED replacements to be fine
> with higher line voltage because they have their own built-in switching
> A lot of modern electronic equipment with switching supplies, are just
> at +20% line voltage and may even run cooler.
> Tim N3QE
> On Sun, Jan 1, 2017 at 11:49 PM, Bill Byrom <time at radio.sent.com>
>> There are a couple of recent threads concerning the power line mains
>> voltage standards. After a bit of research and thinking, I have found
>> that this is a complex topic. The simple answer is:
>> * The standard in the US for the past 50 years has been 120/240 V +/-
>> RMS at the service entrance to the building. This is a range of
>> 114/228 V to 126/252 V.
>> * The load voltage could be as low as 110/220 V and as high as 125/250
>> and be within specifications.
>> There are two voltage measurement points to consider:
>> (1) Service voltage: This is the RMS voltage measured at the service
>> entrance to the building (at the metering point).
>> (2) Utilization voltage: This is the RMS voltage measured at the load.
>> It might be measured at an unused socket in a power strip feeding
>> several pieces of electronic equipment, for example. There are of
>> course many different utilization voltages present in a home or
>> business, depending on where you make the measurement.
>> Most US homes and small businesses are powered by what is commonly
>> called a "split-phase" 240 V feed. The final distribution system
>> transformer has a 240 V center-tapped secondary. The center tap is
>> grounded, and three wires are fed to the building (actually it might
>> up to around 6 houses):
>> (1) Leg L1 or phase A (red wire) -- This wire will measure 120 V to
>> neutral or 240 V to Leg L2.
>> (2) Neutral (white wire) -- This wire is grounded at the distribution
>> system and at the service entrance to the building.
>> (3) Leg L2 phase B (black wire) -- This wire will measure 120 V to the
>> neutral or 240 V to Leg L1.
>> Large appliances and HVAC systems are usually connected across L1-L2
>> (240 V), while most sockets are on circuits either connected across
>> neutral (120 V) or L2-neutral (120 V).
>> The voltages I have described are the current standardized values for
>> the service voltage which have been in general use for about 50 years
>> (120/240 V +/- 5%). I believe that the original systems installed
>> 1940 were designed for a 110/220 V nominal service voltage, but after
>> report in 1949 the nominal service voltage was increased to 117/234 V,
>> as specified in ANSI C84.1-1954. After research in actual buildings,
>> the 1960's the nominal service voltage was increased again, to 120/240
>> in the ANSI C84.1-1970 standard. The purpose is to keep the
>> voltage at the load above 110/220 V.
>> The voltage at the service entrance should in most cases be in Range A
>> (120/240V +/-5%). On each 120V leg the service voltage should
>> be between 114 and 126 V. The utilization voltage at the load should
>> between 110 and 125 V due to losses in building wiring.
>> See details of the current specifications at:
>> These voltage specifications were designed for resistive loads and
>> measurement of the true RMS voltage. In most electronic equipment
>> over the past 50 years, the power supply input circuitry is basically
>> rectifier connected to a smoothing capacitor. This leads to high input
>> current surges during the peaks of the waveform, so that the peak
>> voltage is reduced much more by the building wiring resistance than if
>> the load was resistive for the same power consumption.
>> So the waveform shape at different utilization locations in a building
>> (with active equipment loads) may be different, so the voltage
>> by different AC measuring instruments can differ. Many meters are full
>> wave average measuring but calibrated so they only read RMS voltage
>> correctly on pure sinewaves. Other meters are true RMS measuring and
>> will read very close the correct RMS voltage even if the waveform is
>> Bill Byrom N5BB
>> On Sun, Jan 1, 2017, at 12:16 PM, CIW308 VE6OH wrote:
>> > Mark,
>> > CSA have standards for over and under voltage, Typical no more that 3%
>> > over and 5% under if memory serves me.
>> > This might help (
>> > http://www.safetyauthority.ca/sites/default/files/csa-
>> > )
>> > The power companies here in Alberta are generally good about fixing
>> > problems with line regulation.
>> > There can be problems with industrial areas and big welders or motors
>> > staring as I am sure you know.
>> > I am sure they do not want the bill for replacing equipment that was
>> > subjected to over voltage.
>> > On UPSs: I am sure you are aware that may of them are not TRUE
>> > sine wave
>> > so the DMM may not read correctly.
>> > Mitch
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