High incoming supply voltage EV charger shutting down

[Intsjones]

Hello,

I have a EV charger that is reporting over voltage and is unable to charge. the charger will operate up to 253V
The solar inverter reports voltages below 253V and when the solar is shutdown and isolated the incoming supply reports voltages in excess 248V consistently, peaking at 256V. after a vist from the DNO latest peak is 254, when they visited they measured 252V in the middle of the day and declared no action required. Requested a voltage logger but they declined. The peak voltage measured by the EV charger and a simple plug in device off the main circuit.

The DNO said the high incoming voltage is not a problem and blamed the EV charger, prevalence of solar installation in the area and proximity to the sub station. They say to cope with demand they have upped the voltage so it will typically be around 250V in our area. I have been back to the EV charger company, they say their product is behaving as expected. I have checked the specifications of othe EV chargers and 253V appears to be maximum and I don‘t want to risk damaging the car when charging.

So this brings me to looking at installing a voltage optimisation device. I am only looking at it to limit the incoming voltage to between 220V - 240V, so that voltage remains within the operational range of the EV charger. I have seen various models from GWE, Givenergy, Cudis mostly rated a 63A. There seems to be a significant price difference for those rated at 100A, the primary difference appears to be the presence of a 63A MCB and a possibly smaller transformer. I have an incoming DNO fuse at 100A, the consumer unit with the EV charger and solar circuits has a 100A isolator switch without SPD (this is separate from the main house consumer unit). Is it feasible to just install voltage optimisation for this part of the system or would there be a risk of nuisance tripping using a device limited to 63A?

Let me just stress, I have no interest in saving money by limiting the voltage. I just want to ensure the voltage remains in range that the EV charger will operate safely and doesn’t cause an issue. At present I am stuck between the DNO, the EV charger supplier both saying they are operating correctly. If I can get to a point where the supply voltage is no longer an issue but there is still a problem with the EV charger, I can go to battle on that front.

Thank you for any constructive advice.

 

[Rockingit]

Interesting one, this, and I'd be keen to hear thoughts from @Julie . My initial reaction is that a DNO shouldn't be able to simply increase a nominal voltage just to overcome issues on their network - am sure that ESQCR will have something to say on that.

To expand on the maths a little, in case you/others don't know - the nominal voltage in the UK is 230v. However, that was as a result of European harmonisation many years ago when the UK was 240v. In a means to sidestep actually making any real-world changes to the networks, the UK regulations were amended so that voltage tolerances became -6 / +10% = ie, 230 + 23 = 253v which meant that 240v was still perfectly acceptable. This is why your charger is stated at that rate, however it's unlikely to be having a happy time constantly maxed out.

Also - this does need some precision metering and data logging over time as what you could be seeing is the effect of basically mathematical rounding - so your inverter is saying 252 when it's actually reading 252.5 and then the charger could be declaring 253 (and thus shutting down) when it's reading the same 252.5 To be clear - that's just one guess out of several without having a whole heap more information.

 

[Rockingit]

This is lifted directly from ESQCR 2020 (page 14, for quick ref) -

(2) Unless otherwise agreed in writing between the distributor, the supplier and the
consumer (and if necessary between the distributor and any other distributor likely to be
aVected) the frequency declared pursuant to paragraph (1) shall be 50 hertz and the voltage
declared in respect of a low voltage supply shall be 230 volts between the phase and neutral
conductors at the supply terminals.
(3) For the purposes of this regulation, unless otherwise agreed in writing by those persons
specified in paragraph (2), the permitted variations are—
(a) a variation not exceeding 1 per cent above or below the declared frequency;
(b) in the case of a low voltage supply, a variation not exceeding 10 per cent above or 6
per cent below the declared voltage at the declared frequency;

 

[Rockingit]

Voltage drops on public networks do happen at peak times, thus have to be accounted for, and then will slowly rise back up to maximums in off-peak times - for example it's not unusual to measure 243v in a town centre building by day and then at midnight be getting 248v. It also works the other way, too - I live fairly rurally in Somerset and in a previous house there was always a notable dip in the lights around 4pm - when the farmer down the road fired up the milking parlour!

 

[Intsjones]

Thanks for the responses so far. just to add have been monitoring the voltage over a number of days via the EV charger and a plug in device for example

18 April - middle of the day Max Voltage 258.5 Min Voltage 241.8 Voltage 254.9

Does anyone have a suggestion for an affordable voltage monitoring kit that can be used to monitor the incoming supply over a period of time? that will not interfere with any other CT device on the incoming supply.

 

[Rockingit]

Have a chat with Test Meter (they are/were sponsors on here and are thoroughly nice people) about renting the right bit of kit for a while, although you might have to enlist a local sparks to help you set it up properly.

Hire Power Quality Analysers - UK - Yorkshire - Leeds

Weekly hire of Chauvin Arnoux PEL 103 Power Quality Analyser. Competitive prices on energy loggers please phone 0113 248 9966 to arrange your hire.

www.test-meter.co.uk

 

[Rockingit]

R-Fur has contacted me to post the following for him as he doesn't have access to post in the DIY section.....

The DNO are required to maintain the voltage within the prescribed limits and if it is out with they have a fixed period to rectify (I think 12 months) I would advise the OP to write to the DNO with a registered letter so that the date is noted and they know you are serious. I have used this course a couple of times with favorable results.
Incidentally I was commissioning an IDNO substation last week and the DNO Engineer said that his company is now changing the tap changers in all their secondary substations from tap 3 to tap 2 because of the effect of embedded generation. But it would take years to get around them all as they need to shut them down to do the change.