Voltage drop in house - what to expect

KCross

I have the upgraded 16kVA supply.
I have a heat pump and an electric car (6.6kW). I also run various appliances at night (dishwasher and dryer mainly).

Everything has been running fine until the last few months when the heat pump has tripped twice (at 5:30am and 5:50am) for what appears to be low voltage based on the alarm it threw. It was an internal breaker on the Heat pump that tripped, not the breaker in the distribution board.

When the heat pump comes on the lights do flicker/dim.
I don't have any other issues or switches tripping etc.


I have a UPS which shows voltage and I also have one of those cheaper plugin type energy monitors and it shows voltage as well.... its generally steady enough at 230V but I have seen it go as low as 216V when multiple items are running (particularly heat pump and car). Every item I turn on drops it another few volts.

I suspect its going lower than 216V, particularly on heat pump startup, but I just haven't observed it yet.

I have sent an email to the ESB to request a voltage monitor as per their web page
https://www.esbnetworks.ie/existing-connection/voltage-issues

As per that page they are allowed ±10% of 230V so 207-253V is "allowed".


So, my questions....

1)
What is the boards wisdom on this. Do you have to regularly drop below 207V for the ESB to do anything or is it enough to have it happen once or twice to "force" them to do something about it?


2)
If they do agree I have a voltage issue, what is the actual solution? Is it a new transformer? FYI: It is a shared transformer with about 4 other houses.

Anyone here had voltage issues and had it solved by ESB. If so, how did they resolve it?


3)
If its a new transformer what size one should I be "insisting" on. I know I can't insist on anything as such but I'd still like to know so I can push things.


thanks

ESB are only responsible for the voltage at the distribution board. The rest of the installation is your own and ought to be spec-ed to a maximum of 3% drop.

They can tweak the secondary winding of the transformer to suit. The higher the transformer output though the less power you can push onto the grid if you get solar PV.

Bruthal

If the voltage is a little low, the heat pump compressor starting will be slightly slower getting up to speed, and so could trip its breaker due to a slightly longer starting current duration. This tripping would be at startup or just after.


If the voltage is badly low, it might trip due to a higher running current than normal because its not up to proper speed (motor slip is higher with low voltage). This tripping might be while it is running a while.

Or possibly the heat pump or its compressor has a problem.

The heat pump starting would probably cause a noticeable dip in voltage at the instant of starting, in most houses, even when all is functioning properly.

KCross

Thanks for the input. You'll need to educate me here.

Sir Liamalot wrote: »

ESB are only responsible for the voltage at the distribution board. The rest of the installation is your own and ought to be spec-ed to a maximum of 3% drop.

When you say it should be spec'd for 3% drop, are you referring to cable sizes and lengths?

I'm reasonably confident the cable sizes etc are good particularly for the heat pump and car charge point as they have dedicated cables and are sized according to spec. (e.g. charge point has 10mm2 cable).

Everything else in the house is run of the mill really (No electric shower) and at the times in question everything else would be off anyway.

Sir Liamalot wrote: »

They can tweak the secondary winding of the transformer to suit. The higher the transformer output though the less power you can push onto the grid if you get solar PV.

Can you explain that?

Solar PV is a distinct possibility in the years ahead so Im interested what the issue is there. I thought exporting to the grid was simply a case of excess kW's. How does the transformer windings inhibit you exporting?

If you have a meter with min/max mode you can make a set of "probes" from a 13A plug and let it sit there recording as long as the battery lasts (4-5 days).
Flukes don't auto-sleep in min/max mode...dunno about the rest.

I'm sure someone will be along to say that such "an appliance" is illegal to plug into your house but the reality is it's safer than dangling probes from a socket.

KCross

Bruthal wrote: »

If the voltage is a little low, the heat pump compressor starting will be slightly slower getting up to speed, and so could trip its breaker due to a slightly longer starting current duration. This tripping would be at startup or just after.


If the voltage is badly low, it might trip due to a higher running current than normal because its not up to proper speed (motor slip is higher with low voltage). This tripping might be while it is running a while.

Or possibly the heat pump or its compressor has a problem.

The heat pump starting would probably cause a noticeable dip in voltage at the instant of starting, in most houses, even when all is functioning properly.

System was recently serviced and no issues found so Im hoping there isn't anything up there.


Interestingly on both occasions it has tripped it was on the night that it was doing its legionella boost. Maybe it was using additional power to achieve that.

KCross

KCross wrote: »

When you say it should be spec'd for 3% drop, are you referring to cable sizes and lengths?

I'm reasonably confident the cable sizes etc are good...

Yes, exactly. It's something you can measure or calculate, don't assume because some lad said....

KCross wrote: »

Can you explain that?

Very simple principle of opposing voltages. The higher the incoming voltage the less available current your system has because it needs to maintain a higher voltage to get the power out the door. The Grid Tie Inverter is a syncing switching regulator that needs to be higher than the incomer to push against it or deliver power to the house loads.

Not that it matters an awful lot in Éire because they won't pay you for export.

2011

KCross wrote: »

I have the upgraded 16kVA supply.
I have a heat pump and an electric car (6.6kW). I also run various appliances at night (dishwasher and dryer mainly).

If you look at 525 in the National Rules for Electrical Installations you will see the following:

525.1 Under normal serviceable conditions, the voltage at the terminals of any current-using equipment shall be not less than the lower limit set by the manufacturer.


Based on this:
1) Do you know what the lower limit set by your manufacturer is for your heat pump?
2) Have you taken this measurement under load conditions when other large loads are also on? - If so what voltage did you measure?

525.2 The cross-sectional area of every current-carrying conductor shall be such that the drop in the voltage between the main supply point in the installation is not more than the following when the conductors are carrying the full load current:

- 4% of nominal voltage in installations and parts of larger installations rated not greater than 80A, circuits at extra low voltage excepted.

According tot eh above:
As the nominal voltage is 230 VAC this means that the maximum permissible volt drop is 9.2 VAC (**** 4% of 230).

**** Note: The ETCI have issued a few corrections / clarifications over the years so this 4% value may have changed. Perhaps other posters can advise. I am a little out of touch as I have been working on projects outside of Ireland for the last few years.

I have a UPS which shows voltage and I also have one of those cheaper plugin type energy monitors and it shows voltage as well.... its generally steady enough at 230V but I have seen it go as low as 216V when multiple items are running (particularly heat pump and car).

Hardly a calibrated test instrument, but perhaps it is an accurate reading.

Every item I turn on drops it another few volts.

This is because volt drop is a function of two things:
1) Resistance
2) Current.

So if you increase the resistance of any conductor within the circuit or increase the current flowing (by connecting more loads) thee volt drop will increase.

1)
What is the boards wisdom on this. Do you have to regularly drop below 207V for the ESB to do anything or is it enough to have it happen once or twice to "force" them to do something about it?

You did the right thing by contacting the ESB. They will assess with proper test equipment over a protracted period.

2)
If they do agree I have a voltage issue, what is the actual solution? Is it a new transformer? FYI: It is a shared transformer with about 4 other houses.

It could be. This will be decided on a case by case basis.

3)
If its a new transformer what size one should I be "insisting" on. I know I can't insist on anything as such but I'd still like to know so I can push things.

Leave that to the ESB. You can help them size it by providing them with an accurate description of your load profile.

I'm reasonably confident the cable sizes etc are good particularly for the heat pump and car charge point as they have dedicated cables and are sized according to spec. (e.g. charge point has 10mm2 cable).

Just because the cables are 10 mm sq. does not mean that they are correctly sized. For all you know the volt drop on the cable between the ESB meter and your distribution board is undersized. Therefore the volt drop is too high before it even reaches the 10 mm sq. Remember one of the factors that should influence cable size is the length of cable run.

Please answer the following:
How long is your 10 mm sq. circuit to the heat pump?
How many kW is the heat pump?
How long is the cable run from the ESB meter to your distribution board? I would think that this cable should be a minimum of a 25 mm sq.

KCross

Thanks, for the input

2011 wrote: »

1) Do you know what the lower limit set by your manufacturer is for your heat pump?
2) Have you taken this measurement under load conditions when other large loads are also on? - If so what voltage did you measure?

1) I don't know. I'm looking at the spec sheet for it and it doesn't list it. I will dig a bit more.
2) As you have said, I don't have industry grade measurement tools and I don't have a profile of the figures over time... just snapshots in time. I've seen it go to 216V with car, heat pump and general background house load.

2011 wrote: »

Hardly a calibrated test instrument, but perhaps it is an accurate reading.

True. UPS's tend to be fairly accurate though. They are protecting equipment from low/high voltage so its not ****e electronics they are selling. The figure given by the UPS for voltage is the same the voltage figure I get from the plugin monitor so I'm inclined to believe the figures its giving me.

I agree its the ESB's equipment is what is required though and have a profile of the voltage over time.

2011 wrote: »

Leave that to the ESB. You can help them size it by providing them with an accurate description of your load profile.

Will do. I am also planning on adding a second EV to the house so I will let them know and hopefully they will action accordingly. I am a heavy electric user and thats why I paid extra for the 16kVA connection so I'm hoping they resolve it if it is on their side.

2011 wrote: »

Just because the cables are 10 mm sq. does not mean that they are correctly sized. For all you know the volt drop on the cable between the ESB meter and your distribution board is undersized. Therefore the volt drop is too high before it even reaches the 10 mm sq. Remember one of the factors that should influence cable size is the length of cable run.

I'm confident of the tails from the meter to my board is correct. It was sized on the basis of a 16kVA connection when the house was built. I paid extra for the tails once the electrician realised I was getting a 16kVA connection.

Im also confident of the charge point cable, if anything that's over sized.

I haven't eyeballed the heat pump cable. I'll double check that one. The heat pump was installed by a reputable company and the wiring was done by my own electrician under their instruction and they cross checked so they had no reason not to pull up my electrician on it if he under sized it. It would in their best interest to call him out so I'm assuming its good but I will double check.

2011 wrote: »

Please answer the following:
How long is your 10 mm sq. circuit to the heat pump?
How many kW is the heat pump?
How long is the cable run from the ESB meter to your distribution board? I would think that this cable should be a minimum of a 25 mm sq.

The 10mm2 was for the charge point. I need to double check the HP cable.

The HP is rated 12kW output. (NIBE F1145 12kW)

About 20m, at a reasonable guess, from the distribution board to the meter.

2011

KCross wrote: »

2) As you have said, I don't have industry grade measurement tools and I don't have a profile of the figures over time... just snapshots in time. I've seen it go to 216V with car, heat pump and general background house load.

If a correct reading this is not good.

True. UPS's tend to be fairly accurate though.

You can't make a blanket statement like that.
Some are, some aren't. You get what you pay for.

They are protecting equipment from low/high voltage so its not ****e electronics they are selling.

In every case? I don't agree.
For example, look at this beauty, it costs less than £40, somehow I doubt it is high quality.

The figure given by the UPS for voltage is the same the voltage figure I get from the plugin monitor so I'm inclined to believe the figures its giving me.

It is not my intention to say that you necesserialy have inaccurate measurements, I am just pointing out that perhaps they are inaccurate.

I am a heavy electric user and thats why I paid extra for the 16kVA connection so I'm hoping they resolve it if it is on their side.

Right now you can't be sure that the issue is not on your side. It is also possible that there is an issue on both sides.

I'm confident of the tails from the meter to my board is correct. It was sized on the basis of a 16kVA connection when the house was built. I paid extra for the tails once the electrician realised I was getting a 16kVA connection.

It would be interesting to know the following with all measurements taken at the same instant:
1) What the voltage is at the meter box at a time of heavy (but normal) load use.
2) What the voltage is at distribution board at a time of heavy (but normal) load use.
3) What the voltage is at the heat pump at a time of heavy (but normal) load use when the heat pump is running.

Im also confident of the charge point cable, if anything that's over sized.

Perhaps it is, but it dose not necessarily follow that the heat pump is.

I haven't eyeballed the heat pump cable. I'll double check that one. The heat pump was installed by a reputable company and the wiring was done by my own electrician under their instruction and they cross checked so they had no reason not to pull up my electrician on it if he under sized it. It would in their best interest to call him out so I'm assuming its good but I will double check.

Also check length of run.

About 20m, at a reasonable guess, from the distribution board to the meter.

That is a long cable run!
So if we look at this table we can see that the volt drop per amp per meter for a 16 mm sq. T & E cable is 0.0028 volts.

So let's say you are drawing65 A and your distribution board is fed with a 16 mm sq. T & E cable (a pretty standard cable for supplying distribution boards) then:
The volt drop on a 16 mm sq. cable is = 65 x 20 x 0.0028 = 3.64 V
So this means that the volt drop from the distribution board to the heat pump should not exceed 5.56 volts (max. permissible VD of 9.20 - 3.64 volts)

The HP is rated 12kW output. (NIBE F1145 12kW)

So what size electrical load is it? If the output is 12 kW the electrical input will be considerably less.

KCross

Let me eyeball those cables later today and I'll be back to you.

KCross

2011 wrote: »

You can't make a blanket statement like that.
Some are, some aren't. You get what you pay for.

Of course. I did say "tend" rather than a blanket statement!

FYI: My UPS is an APC. Not in the cheap Chinese bracket anyway.

Im not under any illusions here. I understand it requires proper test gear, which is why I've asked ESB to come out with theirs.

2011 wrote: »

That is a long cable run!

I've eyeballed the cables.

The tails from meter to distribution board is 25mm² and is about 20m. Probably less.

The car charge point is using 10mm² and is about a 25m run from the distribution board.

The Heat pump is right next to the distribution board, so give it 1-2m max.
I can only see a few inches of the heat pump cable and it doesn't have a marking on that piece but is the same size as the charge point cable. e.g. The diameter of the red cable is ~6mm. Its the same as the car charge point so I'm 99% sure the HP is using 10mm² cable as well.


Also bear in mind that the two trips I've had happened at 5:30am and 5:50am so the only things running would be the heat pump and car charger so as long as those two things are sized/wired correctly I think my internal wiring should stand up to scrutiny but lets see what ESBn say.

2011 wrote: »

So what size electrical load is it? If the output is 12 kW the electrical input will be considerably less.

Its COP is 4.81 and since its rated at 11.88kW output, its input is around 2.47kW according to the spec sheet. It can go beyond that though, if it needs additional power it can call on it via an internal immersion heater. It rarely uses that though but maybe it is using it at the times it tripped. As I said, the two times it tripped it was during its legionella program where it boosts the water to kill bacteria.


I'll fire off an email to the installers and see if they can tell me what min voltage the HP will tolerate.

2011

From what you have described it sounds like your cables are of sufficient size. I think you are making the correct call in contacting the ESB. Please update us as to their findings.

Risteard81

KCross wrote: »

As per that page they are allowed ±10% of 230V so 207-253V is "allowed".

Not quite correct. The supply tolerances are 230V +10%/-6% in some jurisdictions (where it was traditionally 240V) and 230V +6%/-10% in others (where it was traditionally 220V).

I don't believe the +/-10% tolerance ever came into force yet.

KCross

Risteard81 wrote: »

Not quite correct. The supply tolerances are 230V +10%/-6% in some jurisdictions (where it was traditionally 240V) and 230V +6%/-10% in others (where it was traditionally 220V).

I don't believe the +/-10% tolerance ever came into force yet.

I don't know but the link I gave is from the ESB Networks website and they were quoting the appropriate EU regulation.

Are they quoting wrong figures for themselves?

Dardania

KCross wrote: »

Risteard81 wrote: »

Not quite correct. The supply tolerances are 230V +10%/-6% in some jurisdictions (where it was traditionally 240V) and 230V +6%/-10% in others (where it was traditionally 220V).

I don't believe the +/-10% tolerance ever came into force yet.

I don't know but the link I gave is from the ESB Networks website and they were quoting the appropriate EU regulation.

Are they quoting wrong figures for themselves?

I too have a recollection that the CER require something tighter than +\-10%

The time that the trip occurs might be interesting - maybe there’s a local (local to the MV network) heavy load coming on like a pumping station or similar, suggesting a problem further up the network.

I recall a few years ago some company trying to flog a voltage adjuster for domestic installations - from what I could understand it was online Portion of a UPS, that delivered whatever your set voltage was on its output regardless of input voltage or load. In fact, I think another boardsie had one fitted by ESBN when they experienced voltage issues.

Any way you can load up to the full 16kVA and get a voltage read at the main consumer unit or nearby? Would be revealing...

KCross

Sir Liamalot wrote: »

ESB are only responsible for the voltage at the distribution board. The rest of the installation is your own and ought to be spec-ed to a maximum of 3% drop.

Jumping the gun a bit here but lets assume the issue is on the ESB Networks side and they fix it.... what should I then see....

1) A "constant" 230V ±3%.... so more like 223-237V
or
2) They will deliver more than 230V so that when it drops its more acceptable to my equipment? i.e. I will still see the same voltage drops as the HP and car loads come on.


FYI: Right now, when the heat pump starts the voltage drops by 4V according to the two monitors I have. Assuming my internal wiring is good is that normal or not?

2011

KCross wrote: »

1) A "constant" 230V ±3%.... so more like 223-237V

I doubt that you would get something that steady. If you were part of a housing estate that is fed from a large transformer then your supply voltage would be more stable.

2) They will deliver more than 230V so that when it drops its more acceptable to my equipment? i.e. I will still see the same voltage drops as the HP and car loads come on.

As larger loads are switched on a larger volt drop can be expected. This is particularly the case when a motor starts such as the compressor in the heat pump. This problem is exacerbated if the installation is fed from a smaller transformer (on the ESB side).

FYI: Right now, when the heat pump starts the voltage drops by 4V according to the two monitors I have. Assuming my internal wiring is good is that normal or not?

Its not really that surprising.
The starting current for a direct on line motor can be 6 to 8 times the full load current. So when the compressor motor starts the current demand soars for a short time. The volt drop increases as the current increases and then drops off again as the motor current decreases.

KCross

2011 wrote: »

Its not really that surprising.
The starting current for a direct on line motor can be 6 to 8 times the full load current. So when the compressor motor starts the current demand soars for a short time. The volt drop increases as the current increases and then drops off again as the motor current decreases.

I understand the starting currents are much higher but I notice that the voltage stays 4V down while the heat pump is running.

Would you expect that?


As another data point, the voltage was showing as 223V this morning (8:30am) with no heat pump (or anything of note actually) running at the time!

2011

KCross wrote: »

I understand the starting currents are much higher but I notice that the voltage stays 4V down while the heat pump is running.

Would you expect that?

Let’s put it this way:
All conductors have a resistance. Let’s say we have a conductor with a resistance of 5 ohms. If we pass a current of 10 amps through it the volt drop across it will be 5 x 10 = 50 volts.
Next, consider all of the conductor resistances to be fixed (because they pretty much are). This means that any increase in load (therefore current) will result in an increased volt drop. Some of the volt drop you are experiencing will be as a result of cables on the ESB side.

As another data point, the voltage was showing as 223V this morning (8:30am) with no heat pump (or anything of note actually) running at the time!

This tells you that there is a bigger picture. Perhaps for example, others connected to the same transformer are drawing a larger load than normal at this time, hence my question in my last post. Can you could answer this question?

KCross

2011 wrote: »

This tells you that there is a bigger picture. Perhaps for example, others connected to the same transformer are drawing a larger load than normal at this time, ...

That was my thought too... maybe several electric showers, kettles, heating etc running. Normally I see a steady 230V on the monitors.

The ESB 24hr monitoring will be interesting.

2011 wrote: »

...hence my question in my last post. Can you could answer this question?

Are you referring to these questions...

It would be interesting to know the following with all measurements taken at the same instant:
1) What the voltage is at the meter box at a time of heavy (but normal) load use.
2) What the voltage is at distribution board at a time of heavy (but normal) load use.
3) What the voltage is at the heat pump at a time of heavy (but normal) load use when the heat pump is running.

I can't answer those. I don't have the equipment to test. I can only tell what the instantaneous voltage is at my UPS.

As said, I normally see 230V steady with no loads.
When the car, heat pump, dryer or kettle are turned on it drops 2-4V per device.... so 230-->226-->224 etc and stays at that level until the devices go off.

Based on seeing 223V this morning with no load from my house I can see why the heat pump would trip if I had other things running before it started... lets say Heat pump trying to start when the voltage is already under 220V.

24hr voltage monitor is definitely required. Hopefully ESB respond to me quickly.

2011

KCross wrote: »

Are you referring to these questions...

No, they were from an earlier post. My bad, I did not ask the question I intended to, which is:

Are you in a rural area, or are you sharing a transformer with very few others?

Another point to consider, what load profile did your electrical contractor portray to the ESB when applying? My concern is that you may be using more power that was applied for. In addition when you increase the load in the future you may go further beyond the supply capacity originally applied for. The consequence of this is you may be charged for the costs associated with rectifying this issue.

KCross

2011 wrote: »

No, they were from an earlier post. My bad, I did not ask the question I intended to, which is:

Are you in a rural area, or are you sharing a transformer with very few others?

Rural
5 houses connected to one transformer! Therein lies the problem , I think!

2011 wrote: »

Another point to consider, what load profile did your electrical contractor portray to the ESB when applying? My concern is that you may be using more power that was applied for. In addition when you increase the load in the future you may go further beyond the supply capacity originally applied for. The consequence of this is you may be charged for the costs associated with rectifying this issue.

I applied for the upgraded 16kVA connection in the NC2 form at the time of building the house (2011) and the presence of a heat pump was specified(there is a section on the form for it). I also questioned the local ESB engineer at the time if the transformer was going to be up to the job and he said it was fine based on the current loads he was seeing from the other houses.

I think I'm covered on the load profile. They were told upfront. In fact, looking at the copy of the form right now, I cheekily asked if I could have a dedicated transformer installed. They respectfully declined!


In reality I should be able to use more power. With the 16kVA connection you get an 80A ESB fuse (instead of a 60A one). My main distribution board has a 63A fuse in it so Im not even exceeding a standard connection yet. When I add a second Electric car to the house Im going to have problems or if one of the other 4 houses buys an EV!

KCross

KCross wrote: »

24hr voltage monitor is definitely required. Hopefully ESB respond to me quickly.

They responded. Voltage monitor to be fitted within 10 working days.

I have now logged this order for you.The order will now be assigned to a Network Technician within 10 working days who will install a voltage recorder at the property to track the level of power.
A report will be drawn from the voltage recorder that will help the local area office determine what, if any follow up action is required.
Where the voltage is found to be within the standard, a letter will be issued from the local office advising the customer of same.
Where the voltage is found to be outside of standard, the details will be passed to the local Engineering Officer to design a plan to rectify the issue.

Lets see what that shows.

2011

KCross wrote: »

Rural
5 houses connected to one transformer! Therein lies the problem , I think!

Yup, this is what I suspected. This may be part of the issue alright. Another factor could be undersized supply cables on the ESB side.

I applied for the upgraded 16kVA connection in the NC2 form at the time of building the house (2011) and the presence of a heat pump was specified(there is a section on the form for it).

Sure, but other large loads include:
EV charger
Instantaneous shower

....and perhaps:
Electric hob?
Electric oven?
workshop / welder?
Other?

I think I'm covered on the load profile.

Good.

In reality I should be able to use more power. With the 16kVA connection you get an 80A ESB fuse (instead of a 60A one). My main distribution board has a 63A fuse in it so Im not even exceeding a standard connection yet.

From memory I don't think that those fuse ratings are correct (I could be wrong).
Remember at unity power factor 16kVA is about 70 amps.

KCross

2011 wrote: »

Sure, but other large loads include:
EV charger
Instantaneous shower

....and perhaps:
Electric hob?
Electric oven?
workshop / welder?
Other?

None of those except the EV charger (32A).
My showers are mixer showers driven by the well pump. A 3 bar shower... nothing like it!

Even if I had all of those, the two trips so far were at a time when we were all asleep so the Heat pump and EV charger were the only things running of any note.

2011 wrote: »

From memory I don't think that those fuse ratings are correct (I could be wrong).
Remember at unity power factor 16kVA is about 70 amps.

The way ESB state it is...
12kVA gives you a 60A fuse with a supported "52A max demand averaged over 10mins".
16kVA gives you a 80A fuse with a supported 70A max demand averaged over 10mins.

2011

KCross wrote: »

None of those except the EV charger (32A).

Interesting, less loads than I thought.
I would guess that the EV charger would draw far less than 32A ost of the time.

Even if I had all of those, the two trips so far were at a time when we were all asleep so the Heat pump and EV charger were the only things running of any note.

That is of little consequence, as discussed there is a "bigger picture".

The way ESB state it is...
12kVA gives you a 60A fuse with a supported "52A max demand averaged over 10mins".
16kVA gives you a 80A fuse with a supported 70A max demand averaged over 10mins.

Fair enough.

KCross

2011 wrote: »

Interesting, less loads than I thought.
I would guess that the EV charger would draw far less than 32A ost of the time.

While charging it takes a constant 30A, usually for about 2-3hrs depending on how low the battery was. It always charges between 5-8am so that its ready to go when I wake up.

2011 wrote: »

That is of little consequence, as discussed there is a "bigger picture".

Indeed, what I was referring to was that my load profile, even if I had welders and what not on the premise, they were not on at the time. I only had two loads of any consequence during the two trips... Heat pump and EV charger.

Assuming they are wired appropriately I figure my load profile is good... the issue is, as you said, a bigger picture problem.


Thanks for your input so far! I will be back when I have an answer from them.

Dardania

Could any of those loads have any dodgy harmonics, causing the trip?

Those heat pumps have VSDs? Or mange the power electronics in the car charger?

KCross

Dardania wrote: »

Could any of those loads have any dodgy harmonics, causing the trip?

Those heat pumps have VSDs? Or mange the power electronics in the car charger?

I don't know, those questions are beyond my capability!

I do know the heat pump has a soft starter to stop current spikes on startup.

VSD's and harmonics.... not a clue.

I will add, the heat pump is running fine since 2012 with not a single trip. I have the car for two years and no issues.

The heat pump has tripped twice now.... end of Nov and Jan. I ignored it as a once off in Nov as it hadn't happened before. When it happened again I started to look at the voltage readings.

We've had new neighbours recently and maybe their power usage is higher than the previous ones. Its all a guessing game until I get the voltage records.

brightspark

It could also be a loose/bad connection on your own main incoming cables/fuses/circuit breakers.

Any sign of heating anywhere?

2011

Dardania wrote: »

Could any of those loads have any dodgy harmonics, causing the trip?

The EV charger would have an DC charging circuit which I would suspect is a nonlinear load, so yes.

Those heat pumps have VSDs?

Not likely in a small domestic heat pump.

2011

KCross wrote: »

While charging it takes a constant 30A, usually for about 2-3hrs depending on how low the battery was. It always charges between 5-8am so that its ready to go when I wake up.

I am guessing that you mean 30A output from the car charger, not 30A on the input at 230 V ?? Please confirm.

KCross

brightspark wrote: »

It could also be a loose/bad connection on your own main incoming cables/fuses/circuit breakers.

Any sign of heating anywhere?

Im not a spark but I haven't seen any of those signs in the meter or distribution board but as I said Im not a spark so I could miss it.

2011 wrote: »

The EV charger would have an DC charging circuit which I would suspect is a nonlinear load, so yes.

Its a AC charge point. The AC-DC conversion occurs in the car itself. I doubt/dont-think that would have any effect back in the house electrics but I could be wrong.

2011 wrote: »

I am guessing that you mean 30A output from the car charger, not 30A on the input at 230 V ?? Please confirm.

Not sure of the distinction you are making.
Its 30A being drawn by the car from the charge point. The car has a 6.6kVA charger in it.

An EV charge point is no more than a fancy outdoor socket with some smarts built in to handshake with the car.

2011

KCross wrote: »

Its a AC charge point. The AC-DC conversion occurs in the car itself. I doubt/dont-think that would have any effect back in the house electrics but I could be wrong.

I was just Googling this, you are correct the DC conversion happens in the car. However this makes not difference, the circuit is exactly the same, therefore the effects are too.

Not sure of the distinction you are making.
Its 30A being drawn by the car from the charge point. The car has a 6.6kVA charger in it.

If a heater were to draw 10 amps from a car battery the power dissipated would be 120 watts (12 x 10).
Whereas if a heater were to draw 10 amps from a 230V supply the power dissipated would be 2300 watts (230 x 10).
My point is that 30A doesn't mean much without a voltage reference.

When you said that 30 A was drawn I was not sure if meant that this was the DC current drawn from the output side of the car charger at a (possibly) lower voltage or if it was 30 A drawn from the mains voltage supply.

Out of interest how did you measure 30A ? Is this displayed on the EV charger or on the car dashboard ?

xl500

KCross wrote: »

While charging it takes a constant 30A, usually for about 2-3hrs depending on how low the battery was. It always charges between 5-8am so that its ready to go when I wake up.

What type of Ev do you have can you not set it to charge earlier in the night so as not to coincide with Heat Pump Starting

If EV is Charging at 30a and Heat pump starts heat Pump could be tripping on UV ie Low Voltage protection

KCross

xl500 wrote: »

KCross wrote: »

While charging it takes a constant 30A, usually for about 2-3hrs depending on how low the battery was. It always charges between 5-8am so that its ready to go when I wake up.

What type of Ev do you have can you not set it to charge earlier in the night so as not to coincide with Heat Pump Starting

Shifting the charging wouldn't help. The heat pump comes on whenever it wants to 24/7.

xl500 wrote: »

If EV is Charging at 30a and Heat pump starts heat Pump could be tripping on UV ie Low Voltage protection

Yes, thats what we believe it is, but probably only happens when the voltage is already low to begin with, as both heat pump and car charging occur at the same time everyday and it isn't tripping daily.

KCross

2011 wrote: »

If a heater were to draw 10 amps from a car battery the power dissipated would be 120 watts (12 x 10).
Whereas if a heater were to draw 10 amps from a 230V supply the power dissipated would be 2300 watts (230 x 10).
My point is that 30A doesn't mean much without a voltage reference.

When you said that 30 A was drawn I was not sure if meant that this was the DC current drawn from the output side of the car charger at a (possibly) lower voltage or if it was 30 A drawn from the mains voltage supply.

Out of interest how did you measure 30A ? Is this displayed on the EV charger or on the car dashboard ?

Got ya, its 30A @ 230V. The car charger is 6.6kVA.

There is an app for the car that interrogates the telematics and it shows it pulling 6.6kW. I also have an energy monitor on the charge point and can see it pulling 6.6kW and its well documented that the Leaf pulls 30A (I think its actually 29A).

xl500

KCross wrote: »

Shifting the charging wouldn't help. The heat pump comes on whenever it wants to 24/7.




Yes, thats what we believe it is, but probably only happens when the voltage is already low to begin with, as both heat pump and car charging occur at the same time everyday and it isn't tripping daily.

Ok its almost certainly UV and will probably get worse as other houses increase loads

I was just thinking that those times it tripped was probably the same time as heavy loads in other houses If you set the Car to charge earlier then that load would be removed at that peak time

Its not a long term solution but may help in the short term Voltage is probably much better in the Early part of the night ie 2-4am

KCross

Voltage monitor from ESB attached!

They had to cut power to the house to attach it!

It has a normal clamp on the live but it also has two other cables connected to the meter so they had to cut power to connect those.

I presume that's so they can monitor voltage and current?

Anyway, it's in for a week I think so let's see what happens.

2011

Will be interested to see what happens.

xl500

KCross wrote: »

Voltage monitor from ESB attached!

They had to cut power to the house to attach it!

It has a normal clamp on the live but it also has two other cables connected to the meter so they had to cut power to connect those.

I presume that's so they can monitor voltage and current?

Anyway, it's in for a week I think so let's see what happens.

any results from Voltage monitor

KCross

They haven't come back for the monitor yet.

KCross

After sending them an email earlier in the week they came to pickup the monitor today.

Hopefully I'll have a result in a week or two. I dont know how long it takes them to analyse the data and come up with a solution, if there is indeed a voltage issue.

Will post once I hear something.

KCross

The results are in! Drum roll!....


No issue, according to ESB. Its within spec.


They do see some instances where it is outside the 10% allowed deviation. I requested the raw data and they sent me a graph, which I will post shortly. I need the raw data though as the graph is all bunched up data that doesnt show the spikes. e.g. it doesnt show any instances below 215V and I know it goes there and they have admitted it too.

I am waiting on a call from them today to discuss the results as I'm not entirely happy considering they are admitting it has on occasions gone below 207V!


Maybe there is no issue. Maybe its just their first reply to see if I will go away!

I'll be interested in your opinions once I get the graph and stats posted.

Dardania

KCross wrote: »

The results are in! Drum roll!....


No issue, according to ESB. Its within spec.


They do see some instances where it is outside the 10% allowed deviation. I requested the raw data and they sent me a graph, which I will post shortly. I need the raw data though as the graph is all bunched up data that doesnt show the spikes. e.g. it doesnt show any instances below 215V and I know it goes there and they have admitted it too.

I am waiting on a call from them today to discuss the results as I'm not entirely happy considering they are admitting it has on occasions gone below 207V!


Maybe there is no issue. Maybe its just their first reply to see if I will go away!

I'll be interested in your opinions once I get the graph and stats posted.

I wonder if their defence will be that something happened out on the network somewhere that affected you, and they have addressed the problem so that it won't occur again? You were the only victim of a brownout effectively, due to your high demand.
What's your next step if it happens again - CRU?

KCross

Just off the phone with them.
They are allowed a 5% deviation from the 10% range... i.e. they have to provide voltage at 207V-253V but they can go outside that range 5% of the time... they are well within that 5% in my case so it meets the spec.

The spec (EN50160) is fairly flexible and gives them a lot of wriggle room so I think I'm at the end of the road.

They have also now sent me the raw data which is aggregated at 10min intervals showing min/max/avg for voltage and current. I'm still digesting that data.

Example

13 Mar 2018 05:16:54
V min/avg/max 215.9. 218.8. 222.4
A min/avg/max 40.8 52.3 63.8

The car and the heat pump would be running together at this time which would be 30A+17A and then background house load. The 63A max is probably the start-up current when the heat pump comes on.

Another example..
13 Mar 2018 23:46:54
V 206.8 217.8 225.3
A 16.2 52.2 98.2

tweek84

KCross wrote: »

J

Another example..
13 Mar 2018 23:46:54
V 206.8 217.8 225.3
A 16.2 52.2 98.2

98Amps or am i reading that wrong?

xl500

KCross wrote: »

Just off the phone with them.
They are allowed a 5% deviation from the 10% range... i.e. they have to provide voltage at 207V-253V but they can go outside that range 5% of the time... they are well within that 5% in my case so it meets the spec.

The spec (EN50160) is fairly flexible and gives them a lot of wriggle room so I think I'm at the end of the road.

They have also now sent me the raw data which is aggregated at 10min intervals showing min/max/avg for voltage and current. I'm still digesting that data.

Example

13 Mar 2018 05:16:54
V min/avg/max 215.9. 218.8. 222.4
A min/avg/max 40.8 52.3 63.8

The car and the heat pump would be running together at this time which would be 30A+17A and then background house load. The 63A max is probably the start-up current when the heat pump comes on.

Another example..
13 Mar 2018 23:46:54
V 206.8 217.8 225.3
A 16.2 52.2 98.2

Is there any chance of Putting a Soft start control on Heat pump or you could get a car charger which will adjust its output depending on Voltage of Mains I think some of the newer smart chargers do this

KCross

xl500 wrote: »

Is there any chance of Putting a Soft start control on Heat pump or you could get a car charger which will adjust its output depending on Voltage of Mains I think some of the newer smart chargers do this

There is a soft starter on the heat pump already.

There are charge points that do as you say.... the Zappi will reduce power to the car when the current goes above a certain level. The Tesla Wall connector will share the load to two EV's to ensure you don't blow the fuse.

When I get a second EV I will be installing one of those but however I cut it, when I add a second EV I will be increasing the load not decreasing it so I don't know how that is going to pan out.

The guy did say that there is no issue with putting another monitor in when that happens.

KCross

tweek84 wrote: »

98Amps or am i reading that wrong?

Correct, thats a max rather than a sustained load.

The HP could have been starting while there was already high loads and so it could spike. It is soft start limited to 33A and runs at about 17A.

The car draws 30A continuous.... not sure if it spikes on start or not.

Any other devices that happen to be running (oven, kettle etc) could have been on that that time... I don't know.

That particular data point seems an outlier example tbf. Most of the data points are <60A max when the car and HP are running together.... not sure why that 98A happened.

I did see one other weird example...
17 Feb 2018 14:06:54
V 212.4 223.5 228.1 (min/avg/max)
A 3.7 18.7 110.6

No idea how/why 110A would be possible since 212V is not the lowest voltage recorded (205V) and the average was only 18.7A! Measurement anomalies, I suppose.