How variable is your mains voltage?

[MLXXX]

A perennial topic, at least in recent years,  on audiophile forums, is the purported benefit of running a separate power circuit (or even several power circuits) from the home switchboard to the room where the hi-fi equipment is located. It is said that one advantage of this is to  minimize voltage drop.  That raises the question, "What is the mains voltage to begin with?".

 

Unless you generate (or for a select group of very keen audiophiles these days, "regenerate") your own power, the voltage at your switchboard can be expected to cover a pretty wide range in the course of a 24 hour period.  In addition to the variations that have always existed in mains supply voltage, arising from mismatches between supply by the power authority and demand, a big factor in the summer months these days is the direct local injection of electricity into the grid from other homes in your neighbourhood that are running a mains inverter powered with solar panels.

 

In the last few days, the mains voltage at my home in the inner norther suburbs of Brisbane, during the daylight hours, has covered the range 239V (approx) to 250V (approx).

 

Below is a graph of the variation for the 13th November 2018, as provided by a Sunny Boy inverter located immediately adjacent to the house switchboard. Readings were captured via bluetooth approximately 4 times a minute. [The readings were consistently about 2 volts higher than displayed on a Watts Clever device (model EW-AUS5001) plugged into a power point near the switchboard.]

 

What approximate readings are other forum members experiencing?

 

Does anyone have a mains supply that stays within a tighter range than mine does?  As can be seen below, I've recently had a variation range of about 10 volts during the day. 

 

 

Edited November 20, 2018 by MLXXX

[Addicted to music]

When you get passed the 250v like I had.  

You start to wonder why light globes, CF,  LEDs aren’t lasting is a sure sign that something is wrong. What this will also do is take out coil that’s rated at 240V such 230v Solenoids  found in Gas Boasted solar hot water services, and you’re not going to know until someone has a long shower while the sun doesn’t shine!   That’s an expensive fix! I had it going all the way to 260v.  Reported it. And they clamped it to 240v.

You don’t need a fancy plotter to do this,a typical MM. with a peak hold function will record the peak voltage.   When a call is logged they will attached a logger and will log for 48hrs.  After they will tell you what the next step will be and usually give you a 2wk time frame. 

Edited November 13, 2018 by Addicted to music

[Ittaku]

Mine usually sits at 247V. I've seen it fluctuate from 239 to 254.

[Addicted to music]

12 minutes ago, Ittaku said:

Mine usually sits at 247V. I've seen it fluctuate from 239 to 254.

253v is the limit.  + 10% of 230v.  And there is a reason for it.  I will put money on speculation that they set it this high to prevent PV entering the grid.  So much for being environmentally friendly and reducing carbon admissions.

if it’s over 253 the. You need to document with records such as photgraphs and report it.  

[Ittaku]

1 minute ago, Addicted to music said:

253v is the limit.  + 10% of 230v.  And there is a reason for it.  I will put money on speculation that they set it this high to prevent PV entering the grid.  So much for being environmentally friendly and reducing carbon admissions.

if it’s over 253 the. You need to document with records such as photgraphs and report it.  

I'm aware of that but it was a once off that hasn't been repeated. I keep an eye out for it though. One thing though, my car loves the extra voltage, charging faster than normal.

[Guest rmpfyf]

43 minutes ago, Addicted to music said:

253v is the limit.  + 10% of 230v.  And there is a reason for it.  I will put money on speculation that they set it this high to prevent PV entering the grid.  So much for being environmentally friendly and reducing carbon admissions.

if it’s over 253 the. You need to document with records such as photgraphs and report it.  

 

Nope. There are cases where, for short periods of time, it's permissible to exceed these limits.

[Guest rmpfyf]

@MLXXX reactive power is quite telling there. 

 

Can you overlay a plot of your demand?

[Addicted to music]

6 minutes ago, rmpfyf said:

 

Nope. There are cases where, for short periods of time, it's permissible to exceed these limits.

Why?

[Guest rmpfyf]

6 minutes ago, Addicted to music said:

Why?

 

Because the grid isn't perfect! 

 

Cutting through the detail of the standards involved, it is permissible (on a 10-minute average) to exceed upper or lower bounds for less than 1% of the time. This is why most products are designed to be able to run outside of the 'utilisation range' (English - 'where we'd like it to be' - 205-253VAC).

 

It is possible to exceed the above 1% limits when the grid is not in a normal configuration.

 

We're more concerned with voltage rise owing to local generation, particularly solar PV. 

 

Consistent problems usually mean a distributor needs to come out and reconfigure things at a low-voltage (mains) level.

[Bunno77]

Got to love domestic solar panels. 

[Addicted to music]

38 minutes ago, rmpfyf said:

 

Because the grid isn't perfect! 

 

Cutting through the detail of the standards involved, it is permissible (on a 10-minute average) to exceed upper or lower bounds for less than 1% of the time. This is why most products are designed to be able to run outside of the 'utilisation range' (English - 'where we'd like it to be' - 205-253VAC).

 

It is possible to exceed the above 1% limits when the grid is not in a normal configuration.

 

We're more concerned with voltage rise owing to local generation, particularly solar PV. 

 

Consistent problems usually mean a distributor needs to come out and reconfigure things at a low-voltage (mains) level.

No, that’s not what the documented guide lines are all about.  

Up to 230v +10% is acceptable, anywhere over the specs a consumer has the right to sue.

Where did you get that info and where is it documented  that even a slight over supply is acceptable over a short period of time?

All products have a rating and the rating is 240V.   Anywhere out this then most manufacturers will void warranty.

[Guest rmpfyf]

2 minutes ago, Addicted to music said:

No, that’s not what the documented guide lines are all about.  

Up to 230v +10% is acceptable, anywhere over the specs a consumer has the right to sue.

Where did you get that info and where is it documented  that even a slight over supply is acceptable over a short period of time?

All products have a rating and the rating is 240V.   Anywhere out this then most manufacturers will void warranty.

 

Not correct at all. 

 

Nominal range is 230VAC +10%/-6%. The rest you'll find in current versions of:

 

AS60038 (Standard Voltages)

AS/NZS3000 (Wiring rules)

AS61000.3.100 (Electromagnetic compatibility (EMC) Limits—Steady state voltage limits in public electricity systems)

AS/NZS61000.4.30 (Electromagnetic compatibility (EMC) Testing and measurement techniques - Power quality measurement methods)

Few other docs here and there though they're the main ones.

 

Short run variations are possible because load and generation vary dynamically.

 

The national rating is 230VAC, not 240VAC - has been for a few years.

 

Most products are engineered to exceed the utilisation voltage range, and no distribution network in Australia will warranty damage to equipment that failed relative to a power supply matter consistent with reasonable supply in the area - relevant documentation is on each of their websites.

[Addicted to music]

28 minutes ago, rmpfyf said:

 

Not correct at all. 

 

Nominal range is 230VAC +10%/-6%. The rest you'll find in current versions of:

 

AS60038 (Standard Voltages)

AS/NZS3000 (Wiring rules)

AS61000.3.100 (Electromagnetic compatibility (EMC) Limits—Steady state voltage limits in public electricity systems)

AS/NZS61000.4.30 (Electromagnetic compatibility (EMC) Testing and measurement techniques - Power quality measurement methods)

Few other docs here and there though they're the main ones.

 

Short run variations are possible because load and generation vary dynamically.

 

The national rating is 230VAC, not 240VAC - has been for a few years.

 

Most products are engineered to exceed the utilisation voltage range, and no distribution network in Australia will warranty damage to equipment that failed relative to a power supply matter consistent with reasonable supply in the area - relevant documentation is on each of their websites.

Define “short runs”

 

its not listed here.

[Bunno77]

Addicted was correct. 230 + 10% is correct just didn't state the - 6% but undervoltage isn't the issue in this thread.

[Guest rmpfyf]

52 minutes ago, Addicted to music said:

Define “short runs”

 

its not listed here.

 

It's listed within Standards and I'd mentioned the salient bit above. 

 

For 1% of the time on 10-minute averages for measurements compliant with Standards, mains supply can exceed the utilisation range. If the grid is configured abnormally then it can be longer. 

 

If you want to know more SAI Global will sell you the relevant Standards - they're pricey though. 

 

A short run can be infinitely short in time. A hot water tank kicks on at 3.6kW, you get an instant voltage sag before a reaction. Clouds part on a decent PV system, it goes the other way. Load and generation really are very dynamic (particularly at a local level), which is why power quality standards are described in terms of distributions of performance, not absolutes.

 

48 minutes ago, Bunno77 said:

Addicted was correct. 230 + 10% is correct just didn't state the - 6% but undervoltage isn't the issue in this thread.

 

"All products have a rating and the rating is 240V.   Anywhere out this then most manufacturers will void warranty." is incorrect - my comment referred this.

[Addicted to music]

 

3 hours ago, rmpfyf said:

 

Most products are engineered to exceed the utilisation voltage range, and no distribution network in Australia will warranty damage to equipment that failed relative to a power supply matter consistent with reasonable supply in the area - relevant documentation is on each of their websites.

Rubbish, that’s just and expectation and a assumption from the grid.  There’s a thing called money and no company in there right mind in this day and age will be designing and catering for supply voltage to exceed 253V plus.  We don’t, if there was a supply issue we place a logger for 48hrs and if the the supply goes  253 plus  and climbing than that’s outside standard documentation of 253V, that’s enough to void contract and warranty.  They then forced to chase the cost via the supply grid.  

 

One thing to be wary of is if you suspect the issue is rising passed 253V and logged a call. The 1st question after a knock on the door, the question will be “has anything gone faulty?”  Never say no as this gives them a way to escape legal responsibility.  Becuase somethings like solenoids and transformers take longer to die out, even after they have rectified the issue and bring it back to within range.

Edited November 14, 2018 by Addicted to music

[Guest rmpfyf]

2 minutes ago, Addicted to music said:

Rubbish, that’s just and expectation and a assumption from the grid.  There’s a thing called money and no company in there right mind in this day and age will be designing and catering for supply voltage to exceed 253V plus.  We don’t, if there was a supply issue we place a logger for 48hrs and if the the supply expected 253 plus  and climbing than that’s outside standard documentation of 253V, that’s enough to void contract and warranty.  They then forced to chase the cost via the supply grid.  

 

Sorry to disappoint here; what insist are 'expectation and assumption' are actually Australian Standards.

 

Many products are designed to exceed 253VAC supply, including inverters, switch-mode supplies driving a ton of appliances, a whole lot. We have Standards around voltage rise for generating assets (mostly PV inverters) that kick in at 255VAC; in fact many solar inverters will run to 270VAC. A surprising number of products are engineered to steady state performance to 265VAC (or more) and wild variances in supply frequencies consistent with encompassing international power norms. Similarly, there are complete product classes where this isn't feasible (motors etc) and real damage is a risk.

 

There is no hard stop in rules affecting mains supply at 253VAC. None. 

If anything until recently in VIC and NSW (at least) 253VAC was the 'voltage down' threshold (i.e. the mains voltage at which power quality voltage management would kick in).

 

If a potential fault is recorded and logging equipment is applied to observe a supply issue the resulting investigation needs to first prove a breach of both AS60038 and AS61000.3.100, neither of which specify an absolute limit at 253VAC. There is also no 48 hour requirement; often logging goes considerably longer to replicate conditions leading to a fault. 

 

7 minutes ago, Addicted to music said:

One thing to be wary of is if you suspect the issue is rising passed 253V and logged a call. The 1st question after a knock on the door, the question will be “has anything gone faulty?”  Never say no as this gives them a way to escape legal responsibility.  Becuase somethings like solenoids and transformers take longer to die out, even after they have rectified the issue and bring it back to within range.

 

Again, not the case at all. There is zero expectation for customers to be engineers or electricians.

 

Legal responsibilities around liability arising from electricity supply are set by the AER (Australian Energy Regulator), being part of the ACCC (Australian Competition and Consumer Commission). All distribution network service providers are required to provide a fair and equitable claims process which is in no way contingent on what you may or may not say when asked if anything is known to be faulty. No one f***s with the ACCC, not even energy distributors. 

 

The first question is often 'has anything gone faulty' simply to start diagnosis. Nothing more. 

 

A common difficulty for customers is not having had data to justify a supply performance fault - if you're buying a PV system, spend the extra on decent metering, and let it run 24/7. Helps a lot.

[Addicted to music]

I’m not talking about PV and when they are like to enter the grid.

 

infact the preferred range of the grid to the GPO that’s acceptable is 230V +6% and - 2%

  The plus 10% and and expect equipment to run above 253V is just stupid.    Hence the reason why devices such as light globes fail.  Solenoids will start to overheat as they not designed for the overvoltge. I’m very sure that even the SMPU that’s in the gear I work are 240V..  They’re not designed to take input over 253V and that’s a fact.

[davewantsmoore]

When I lived in the city, it was spot on 230v 24/7/365 .... in the burbs now, it's 242, and runs up and down by up to a few percent.

[Guest rmpfyf]

20 minutes ago, Addicted to music said:

I’m not talking about PV and when they are like to enter the grid.

 

infact the preferred range of the grid to the GPO that’s acceptable is 230V +6% and - 2%

  The plus 10% and and expect equipment to run above 253V is just stupid.    Hence the reason why devices such as light globes fail.  Solenoids will start to overheat as they not designed for the overvoltge. I’m very sure that even the SMPU that’s in the gear I work are 240V..  They’re not designed to take input over 253V and that’s a fact.

 

PV is relevant as its sync'd to grid. It's not as though there's an AC voltage for PV systems and another for everything else (line drop asides). You're right about the preferred band, though that's not an upper limit. The current local voltage down signal occurs at 255VAC as per AS/NZS 4777.

 

Equipment is excepted to run beyond 253VAC for short periods of time (<=1%). No equipment I've tested or developed goes into arrested development the second things drift over 253VAC. The limits literally represent the 99th and 1st percentiles of supply voltage. As stated earlier, it's a probability distribution based Standard, not a hard and fast rule. For reference, a bog-standard EDMI smart meter (revenue grade, used often in parts of Australia) works between 45-65Hz, 176-276VAC... and they'll withstand up to 290VAC!

 

Most LED globes will survive supply requirements just fine. So will most equipment - tested to do as much in development and market homologation. If supply is at 250VAC+ for sustained periods of time, different story.

 

Not uncommon to see upper voltage alarm limits in industrial equipment (set by equipment manufacturers) at 258VAC (or a little more - basically the top band + room + accuracy). 

 

This doesn't mean that these swings are great or super for audio applications. Where there's known rise, regeneratiom is potentially a good thing.  ad

 

3 minutes ago, davewantsmoore said:

When I lived in the city, it was spot on 230v 24/7/365 .... in the burbs now, it's 242, and runs up and down by up to a few percent.

 

Big local loads, low local generation, easier to regulate.

[MLXXX]

6 hours ago, rmpfyf said:

@MLXXX reactive power is quite telling there. 

 

Can you overlay a plot of your demand?

Although I capture live data for power demand of my own house, it is with a different system that does not retain the data. However examining a low resolution summary of that data extracted yesterday, I can see that the only heavy load for the day occurred before 10am. It was a 3.6kW (240V) electric hot water heater.

 

(When the inverter is at maximum rated output, turning on that heater results in the inverter reporting a voltage drop of roughly 2.4V, e.g. dropping from 246.0V to 243.6V. For operation at 240V, a 3.6kW element would draw 15 Amps. At a switchboard voltage of 243.6V it would draw 15.225A (disregarding the resistance of the cable from the switchboard to the hot water system). A voltage drop of 2.4V at a current of 15.225A implies an impedance of 0.157Ω (disregarding the fact that the inverter output current will increase when it is delivering its full rated output power at 243.6V rather than at 246.0V) .  At some stage I might try to ascertain the mains source impedance at the switchboard, more accurately.)

 

Anyway, I thought it might be interesting to look at possible correlation between grid frequency, and the mains voltage at my switchboard. Here is a plot using data from yesterday, now including the grid frequency as polled approximately 4 times a minute:

 

 

Edited November 14, 2018 by MLXXX

[Guest rmpfyf]

@MLXXX not so bad. If accurate there's a little bit of stepping outside normal operating frequency band on the low end.

 

Stuff like this is relevant https://www.aemo.com.au/-/media/Files/Electricity/NEM/Security_and_Reliability/Ancillary_Services/2017-06-Frequency-Monitoring---Three-Year-Historical-Trends.pdf

[MLXXX]

52 minutes ago, davewantsmoore said:

When I lived in the city, it was spot on 230v 24/7/365 .... in the burbs now, it's 242, and runs up and down by up to a few percent.

It hasn't been clamped to a tight range in Brisbane in the inner suburbs where I've resided, for many many years, going back to before home solar inverters were a "thing". And it was rather more than 230V, partly because in the early years the nominal voltage was 240V anyway.

A lot of my appliances have 240V appearing next to the model number (e.g. an electric frypan purchased a year ago).  An electric jug I bought recently shows 220V - 240V. 

[Guest rmpfyf]

14 minutes ago, MLXXX said:

It hasn't been clamped to a tight range in Brisbane in the inner suburbs where I've resided, for many many years, going back to before home solar inverters were a "thing". And it was rather more than 230V, partly because in the early years the nominal voltage was 240V anyway.

A lot of my appliances have 240V appearing next to the model number (e.g. an electric frypan purchased a year ago).  An electric jug I bought recently shows 220V - 240V. 

 

Lots of distributors are literally doing the rounds of their feeders once voltages are consistently high and re-regulating.... still it's not an easy game, you're low in winter, high in summer, depends on loads... there's got to be a consistent problem to grab it by the scruff of the neck like that. 

 

I tend to think for some people regeneration really isn't a bad thing if you want consistency. Whether you hit impedance etc to similar performance that grid would give you is another thing altogether.

 

Some people believe ultimate regulation should be in the black boxes of your audio rig, and there's something to be said for that, though I'm with @Addicted to music to a good degree (suggesting mains should be a bit tighter) in that whilst I don't have an 'audiophile' fridge or reverse cycle rig I did pay good money for those I have and I'd like them to last a good while yet.

[Guest Eggcup The Daft]

I guess (without searching to see if it's already covered) that the next question is, what effect does the variation have on an audio system?

 

I guess the worst case is a European product shipped "as is" to Australia expecting 220V and then receiving 250V+. What changes are likely to happen?