Are Over Voltage Problems widespread

[matthunt]

Are any of you seeing High voltage problems in houses with Solar/PV installed in same street?

I attended a call out a few weeks ago due to the fuse board apparently smoking. When i arrived it transpired it was the shower circuit, the voltage measured was 246v and the current 36 amps meaning a 7.5kw shower drawing 8.8kw through a cartridge type Wylex db. The fuse was rated at 30amps and you just could not touch it due to the heat. We all know of the inherant problems with this type of fuse whilst continuing to operate on steady over current. Has anyone else seen this type of problem? as i am aware that multiple PV installs in a street on the same phase will obviously boost the voltage due to the nature of the invertors.

 

[Knobhead]

You can’t escape these two.
W=I*V
Input power x ((1/Efficiency)+1) = Output power.
So 1000W O/P @95% efficiency = 1010.526W I/P.

Most of the places I’ve worked we used 433/250V some of the earlier plants used 550V or 660V. (The higher the voltage, the more power you can cram down a cable).
As an experiment I lowered the voltage at our intake sub. I got nothing but complaints from across the works and two local villages. I’d lowered it to give 400V nominal.
400/230V is, in short, impractical.

To lower the voltage to our works and the villages I turned the AVR down on the 4 20MVA 33/11KV transformer OLTC (On Load Tap Changer). Soon turned it back up again, problems were flooding in from all over.
This all came about due to a problem with cheap crappy VSD’s on one plant. We did change the local tap changer there.

 

[UNG]

Thanks for your coments and link darkwood

I agree with the posibility of the install but unfortunately i do not know what if anything had been changed during the life of the install, shower size / fuse etc. The point was that the increasd voltage had caused the overheating problem due to the excess current.

I find it difficult to wholly suggest that increased voltage is the prime cause of this fault

That was changed in 2008 Glennsparko +/-10%

253-207v and 440-360v nowadays, anyway thats not important to this thread, the thing that surprises me is the lack of undertanding of voltages and the effect on equipment it potenially has with Electricians in the UK

From a Carbon Trust Document published in June 2011

Historically the supply voltage in mainland Europe has been 380/220 volts with a typical
tolerance of ±6%. Steps to harmonise voltage levels were taken in 1995 when the statutory
supply specification in the UK changed to 400/230V+10% -6%. This remains the current
UK position today.

The +/- 10% part of voltage harmonisation was never enacted talking to an SP engineer earlier this year when I found an installation with voltages down at 213v - 218v he said discussions had recently started on possibly introducing it in 3 - 4 years time so at the moment the lower voltage limit is 216v or 376v

So if the 17th Edition Regs are based on 230v (of which the calculations are) and we design the cable calcs disconnection times around this,whose fault is it if the incomming supply is 240-250v (of which it is) and the circuit cannot take this voltage/current and subsequent load.

As with a lot of regulations they will have quite a healthy safety margin built in so I don't think there is anything to worry about