I noticed following information (source:
http://www.mainsfrequency.com/news.htm#2015_1):
Minimum and maximum mains frequency
To clarify the question "how stable is the mains frequency", data of the
last 13 months was analyzed (July 2011 to July 2012). The greatest
fluctuations occurred regularly on the hour change, which is caused by
the use of products of hours. The limits of frequency range allowed in
normal operation (49.8 Hz to 50.2 Hz) were never reached or exceeded
in this period:
* Maximum frequency: 50,164 Hz on tuesday, 13.12.2011, 23:52:54
* Minimum frequency: 49,849 Hz on tuesday, 17.01.2012, 23:02:08
Then I was curious if "leap second" event could be noticed on the main
frequency charts. May be its is no correlation at all.
Regards,
Vlad
On 2017-01-03 12:01, J wrote:
Power utilities tweak the system frequency on a daily basis to keep
MAINS powered clocks correct. I wonder what their correction strategy
was for the leap second?
On Tue, Jan 3, 2017 at 11:05 AM, Vlad <t...@patoka.org> wrote:
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
http://www.patoka.ca/OCXO/60hz-periods-Dec29-Jan2.png [1]
For Dec 31:
http://www.patoka.ca/OCXO/60hz-periods-Dec31.png [2]
It will be interesting to see/compare if anybody else has similar
stats.
Regards,
Vlad
On 2017-01-02 13:00, Tim Shoppa wrote:
What modern loads are actually sensitive to high (say, +10 to +20%)
line
voltage?
Old incandescent light bulbs were among the most sensitive loads in
the
past (so much so, that 130V light bulbs were commonly available from
the
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
regulation.
A lot of modern electronic equipment with switching supplies, are
just fine
at +20% line voltage and may even run cooler.
Tim N3QE
On Sun, Jan 1, 2017 at 11:49 PM, Bill Byrom <t...@radio.sent.com>
wrote:
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
+/- 5%
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 V
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
be
up to around 6 houses):
(1) Leg L1 or phase A (red wire) -- This wire will measure 120 V to
the
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
L1-
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
before
1940 were designed for a 110/220 V nominal service voltage, but
after a
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,
in
the 1960's the nominal service voltage was increased again, to
120/240 V
in the ANSI C84.1-1970 standard. The purpose is to keep the
utilization
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
therefore
be between 114 and 126 V. The utilization voltage at the load should
be
between 110 and 125 V due to losses in building wiring.
See details of the current specifications at:
http://www.pge.com/includes/docs/pdfs/mybusiness/ [3]
customerservice/energystatus/powerquality/voltage_tolerance.pdf
These voltage specifications were designed for resistive loads and
measurement of the true RMS voltage. In most electronic equipment
built
over the past 50 years, the power supply input circuitry is
basically a
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
measured
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
distorted.
--
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- [4]
fia3660-voltagedropcalc.pdf
)
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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[1] http://www.patoka.ca/OCXO/60hz-periods-Dec29-Jan2.png
[2] http://www.patoka.ca/OCXO/60hz-periods-Dec31.png
[3] http://www.pge.com/includes/docs/pdfs/mybusiness/
[4] http://www.safetyauthority.ca/sites/default/files/csa-
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V.P.
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