3 phase 100A power supply - voltage at each phase goes up to 250+ Volts should I be worried?

As I pointed out, you must use accurate metering of a particular type, which must be a very accurate true RMS meter. Normal average reading meters are no good at all if the waveform is even slightly distorted. Data loggers are of this type. Normal multimeters are usually average reading, RMS calibrated, so not much use. The car accuracy is probably very dubious! Its charger will be very well protected against most mains incidents, spikes and excess voltages, including automatic disconnection if it is not happy.

If these voltages are reported by the car software, they may not be that accurate  (5 to 10% off does not affect the cars internal 'is it OK to charge' decision)- if you are concerned, a then a comparison with readings from a proper meter is needed.

Officially the supply may be 230V +10%-6% , so 253 would be the upper bound for 'normal' operations.


In use quite a bit of voltage variation is not normally a  problem unless there are other indications the voltage really is a bit high, the classic used to be failing light bulbs, but less so nowadays with electronically ballasted LEDs and so on.

It may be set up wrongly if a new transformer has gone in to support your supply, and the wrong tap connections  have been set, or if for some reason lots of generation has been added to your substation (I'd think solar panels as a source of voltage rise, but obviously not if the volts only go up at night ?.)

Before panicking, I suggest a cross check with a real meter, or seeing what the car  reports when charging elsewhere.

Agreed - the official range for mains is 230V-6%+10% - i.e. anything between 216.2V and 253V. But then you've got the accuracy of your meter to contend with (which are usually a lot worse than you would hope). If it really is high then the DNO should do something about it - but it might be a fight. I've been on a commercial site where several of the UPSs were complaining of high supply voltage every night (probably >254V) yet the DNO's logger allegedly couldn't see the problem.


If it's high on one or two lines, but low on the others - there is a possibility that there's a bad connection on the N and that's skewing things. (effectively the Ls are right but N (and Earth if TN) have moved from where they should be). That could be an early warning of quite a serious problem (broken PEN).

 

I also got a 4 pole Type 1 surge protection device to be installed (Hager JK101SPD) in-line with the mains incomer so that all the ciruits behind it will be protect.

Unusual - do you have lightning conductors on the building (or close by)? Generally a Type 1 is only specified where lighting in involved and typically only protects the type 2 SPD behind. Normally a Type 2 is needed to protect downstream circuits (and possibly a type 3 downstream of that to protect particularly sensitive equipment). There are combined Type 1+Type 2 where you need both at the same location.


   - Andy.

HI FaeLLe


I assume the ICP has connected you to the national grid - a public supply - and not a private supply? I assume you don't have your own transformer? 


In which case - other than maybe the 4 pole isolator - and how that makes/breaks the neutral; I'd let the national grid worry about the amount of volts they put out there. The kit can almost certainly take 257V. 


All should be OK I think.


Kind Regards


Tatty

It is normal for voltages to move around a bit, although the 257V you suggest is a bit higher (253V) than one would expect. To measure this properly one needs a high accuracy true RMS meter (0.1% or better) which you may not have. It is not a cause for concern anyway, and is very unlikely to damage your car.