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/ > 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- > 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 > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.