Should I request a check for voltage stability from my electrical company?

[mcinque]

This is about 1 hour logging and wasn't the worst day.
Since the check would cost me some bucks if they don't find anything that they consider "abnormal", in your opinion is this something that can be considered "normal" in electric domestic supply stability?
I'm aware that there are tolerances between electrical companies and countries but I'm asking to you all just to understand if I must request the check for the worst day - with many more deep variations - or if this can be enough.

[ataradov]

I'm not a standards expert, but from practice, this is more or less normal. I've seen much worse.

[james_s]

It's hard to tell the duration of those narrow low spikes due to the width of the graph line. Are they sustained dips for a significant duration, or are they just momentary blips caused by something like an air conditioning or heat pump compressor or other large motor load starting? Overall it doesn't look too bad to me, are you having problems like clocks getting reset, computers rebooting or other malfunctions?

[mcinque]

It's hard to tell the duration of those narrow low spikes due to the width of the graph line. Are they sustained dips for a significant duration, or are they just momentary blips caused by something like an air conditioning or heat pump compressor or other large motor load starting?

Their duration is between 1 and 20 seconds. Sometimes it goes 190V and remains like that for half an hour.

I'm the only residential user on this line. The other one is a farmer with 380V water pump motors used for irrigations and probably some other 380V electrical devices. I'm sure he has a "pressure motor" (I don't know how it's called in english a motor that keeps pressure always active 24/h).
This down spikes increase A LOT during spring and summer, where irrigation is needed here.

I noticed this since the first days the electrical company connected su. Since I'm the only residential user, I bet that he never noticed this behavior.

Overall it doesn't look too bad to me, are you having problems like clocks getting reset, computers rebooting or other malfunctions?

No, but I can see the blips just by the light of my livingromm lighting which use standard halogen light bulbs.
I can even hear them when using hairdryer just hearing his rpm change.

[ejeffrey]

I don't know how Italy works, but in the US, those short blips wouldn't be something the power company is going to think are abnormal.  Dropping to 190 for a half hour would be considered abnormal.

Is your standard voltage 220 or 230?  If your standard voltage is 230 +/- 10%, then you are operating on the low side.  That, coupled with sustained drops <200 V would probably be enough for the power company to change the tap on your feeder transformer to bump the voltage up closer to nominal.  But be aware that if the nature of the loading changes, you might end up with overvoltage conditions.

Honestly, if you are the only residential user at the end of a long line mostly feeding industrial farm equipment, you are going to see pretty ugly stuff. 

[jordanp123]

I'm not familiar with the Utility regs in Italy but for the utilities I've worked at in the US, if you had a +-10% swing we would generally consider it abnormal if the swings were sustained for a period of time; or if you had very large excursions from the nominal voltage for any length of time. Assuming your nominal is 220V (Again I'm not sure), then 1-190/220=~13%, so thats a little on the high side of the excursion window. I'm going to agree with ejeffrey in that if they agreed that its a issue they would most likely change transformer taps to compensate.

[aargee]

Most utility suppliers in this part of the world have a standard supply guarantee.
It is usually published somewhere away from public eyes, it may be worth pursuing to see if you can force them to respond to their own guarantee of supply (assuming there is one, of course).

[Lord of nothing]

Assuming your nominal is 220V (Again I'm not sure), then 1-190/220=~13%,

230V. 
You can get an Online UPS for your IT and Test Equitment. An Online UPS put out 230V.

[Zero999]

I'm not familiar with the Utility regs in Italy but for the utilities I've worked at in the US, if you had a +-10% swing we would generally consider it abnormal if the swings were sustained for a period of time; or if you had very large excursions from the nominal voltage for any length of time. Assuming your nominal is 220V (Again I'm not sure), then 1-190/220=~13%, so thats a little on the high side of the excursion window. I'm going to agree with ejeffrey in that if they agreed that its a issue they would most likely change transformer taps to compensate.

I thought the voltage standard across the whole EU was 230V +10% -6%, so it shouldn't go below 216.2V.

[richard.cs]

I thought the voltage standard across the whole EU was 230V +10% -6%, so it shouldn't go below 216.2V.

In former 240 V countries it's 230 V +10/-6% in former 220 V countries it's 230 V +6/-10%. The intention is (or was) to widen it out to +/-10% in the future, and modern equipment for the EU market is normally tested for 230 V +/-10%.

His lower limit should be 206.8 V, and if it's below that other than for brief spikes then the electricity supplier may well investigate, though that depends what the Italian rules actually are. Certainly 190 V for half an hour (as he mentioned) would be considered way out of spec.

[bitwelder]

Just curious: let's suppose there is some (neighbor's) heavy load on the line that is causing these fluctuations.
Would it be possible to detect the type of load (e.g. the type of heavy machinery) by plugging some measurement equipment to the mains, e.g. by measuring noise/harmonics?

[Zero999]

I thought the voltage standard across the whole EU was 230V +10% -6%, so it shouldn't go below 216.2V.

In former 240 V countries it's 230 V +10/-6% in former 220 V countries it's 230 V +6/-10%

Are you sure? I thought the purpose of harmonisation was that it should be the same everywhere, so having different tolerances, for different places doesn't make sense, although this is the EU we're talking about here.

[richard.cs]

Are you sure? I thought the purpose of harmonisation was that it should be the same everywhere, so having different tolerances, for different places doesn't make sense, although this is the EU we're talking about here.

I am absolutely certain it's +10/-6% in the UK (which aligns very well with the previous 240 V +/-6%). My understanding (I'm fairly certain) is that the asymmetric tolerances are the other way around in the 220 V areas with an eventual long-term goal of harmonising on +/-10% - perhaps after the final death of the incandescent lamp but so far as I know there is no date set. Equipment is already designed for 230 V +/-10% (so it can be used everywhere in the EU whatever the local tolerances) and existing substations are not being changed, it might be that the 220 V areas push the voltage up a little once they are allowed to in order to make use of the wider tolerances.

[MatthewEveritt]

Are you sure? I thought the purpose of harmonisation was that it should be the same everywhere, so having different tolerances, for different places doesn't make sense, although this is the EU we're talking about here.

Those values were chosen so both specifications actually come as close as possible - approx. 207V to 243V. Basically a case of fudging the numbers to avoid having to actually change anything.

[dr.diesel]

What measurement point, if not the main feed in your breaker panel (safety issues here) you could be seeing local issues, ie a half a dozen daisy chained receptacles.

I've seen entire large rooms on a 20 amp breaker with 14 gauge wire all daisy chained, more than once.   

[Gyro]

Are you sure? I thought the purpose of harmonisation was that it should be the same everywhere, so having different tolerances, for different places doesn't make sense, although this is the EU we're talking about here.

Those values were chosen so both specifications actually come as close as possible - approx. 207V to 243V. Basically a case of fudging the numbers to avoid having to actually change anything.

Yes. I was tasked with investigating the impact of Harmonization on our industrial gear at the time. The 230V +/- 10% figure was chosen so that everybody already met the requirements of  harmonization and none of the national supply utilities had to change anything (apart from having a little more future leeway). The UK is still 240V +6/-10% (216-254V)

A perfect EU compromise.

[mcinque]

That, coupled with sustained drops <200 V would probably be enough for the power company to change the tap on your feeder transformer to bump the voltage up closer to nominal.  But be aware that if the nature of the loading changes, you might end up with overvoltage conditions.

It's what I fear.

Honestly, if you are the only residential user at the end of a long line mostly feeding industrial farm equipment, you are going to see pretty ugly stuff.

I believe you!

Just curious: let's suppose there is some (neighbor's) heavy load on the line that is causing these fluctuations.
Would it be possible to detect the type of load (e.g. the type of heavy machinery) by plugging some measurement equipment to the mains, e.g. by measuring noise/harmonics?

I guess it would be possible, but I'm pretty confident they are all only inductive machinery (motors) without a proper power factor correction capacitor bank.

What measurement point, if not the main feed in your breaker panel (safety issues here) you could be seeing local issues, ie a half a dozen daisy chained receptacles.I've seen entire large rooms on a 20 amp breaker with 14 gauge wire all daisy chained, more than once.   

Exactly: initally I thought was an issue inside my electric panel or a domestic cabling problem.

But I followed the reverse path going from the mains plugs to the breakers up to the electrical meter and ended reaching the source measuring directly on the unfused three phase supply at the cabinet, before my electric meter (should be ~400V 11KW; I know about high safety risk this entails and I took all the precautions needed to avoid a guaranteed instant death).

I tested all three phases, the results are the same: all three have those glitches, both in respect to each other and to neutral.

The readings does not differ from any measurement taken inside the house so the issue is between the electrical company and me.

I believe that I'm at the end of a line with too small section that obey Ohm's law when one of the farmer's motor starts... I strongly believe that in NO WAY they would change the cable line section because it's a buried line and would require a huge amount of money.

[Lord of nothing]

How about the idea get an UPS? Sure not one with big Battery more for AC - DC - AC Conversion and you get an quite perfect sinus wave.

[ataradov]

There are power inverters designed just for that case. They are not all that expensive and work quite well.

[mcinque]

I have one but only for the PC, DSO and DMM, it's solved partially: I hate the continuous changing in luminosity in the livingroom. Since all my leds lamps died in 1 or 2 years I become tired wasting money in them and started using standard halogen which are pretty good at showing voltage changes

[SeanB]

Try to find a constant voltage transformer, which will reduce those spikes considerably and will remove a lot of the voltage variation, though it will have some heat dissipation and a constant VA draw. Otherwise get some mains power factor correction capacitors ( probably 50-200uF, fed direct from the distribution board via a 30A breaker) to reduce the harmonic distortion on the line. All this will slightly increase your electric bill, though you might want to talk with your power supply engineering department about them installing some power factor correction capacitor banks on their side of the meter by the larger rural customers, to reduce the losses in the line.

[james_s]

Odd you had so much trouble with LED lamps. I replaced most of the bulbs in my house with LED lamps between 2010-2012 and since then I've had only 2 or 3 fail. All of those that failed were used in fully enclosed fixtures despite the warnings not to. Some have a lot of hours on them, the porch lights for example are on a timer and average 12 hours a night.

[SL4P]

Not sure of OPs local authorities, but SeanB’s suggestion in #20 is the right way to go.
A long consumer line, with two customers, one semi-industrial, one residential... the power supplier needs to provide quality of supply.
Even if that means *they* wear the cost of running a new line to the OPs property from the substation.

[mcinque]

thank you all for your replies and advices, I will try the power factor capacitor solution suggested