[time-nuts] Line Voltage [Was: Anyone (ideally in the UK) ...]

Jeremy Nichols jn6wfo at gmail.com
Sun Jan 1 00:19:12 EST 2017

[Sorry for the blank post earlier—TVB reminded me posts have to be plain 
text. My post was sent from my new-to-me iPad, probably in HTML. Have to 
learn how to turn that off!]

I too am concerned about high power-line voltage harming my collection 
of new and old electronics. A couple years ago I spent a lot of time 
documenting the line voltage at our home in northern California. The 
utility was consistently in excess of their 125 VAC specification. It 
took weeks of data before I got them to bring a recorder to my home and 
make their own measurement; once that was done they bumped the voltage 
down a little. The frequency also wanders but averages out to 60 Hertz, 
more or less (not Time-Nuts quality).


On 12/31/2016 11:57 AM, Tom Miller wrote:
> ----- Original Message ----- From: "Dr. David Kirkby (Kirkby Microwave 
> Ltd)" <drkirkby at kirkbymicrowave.co.uk>
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Saturday, December 31, 2016 11:01 AM
> Subject: Re: [time-nuts] Anyone (ideally in the UK) got a spare rotary 
> knob for the 5370B TI counter?
>> On 31 December 2016 at 13:03, EB4APL <eb4apl at gmail.com> wrote:
>>> Hi,
>>> I'm not totally sure about the limits, but I have read several times 
>>> that
>>> in the UK the nominal supply voltage is 230 V +10%/−6% to 
>>> accommodate the
>>> fact that most supplies are in fact still 240 V. The context was 
>>> that a lot
>>> of test equipment failed when operated at around 250 V and many input
>>> capacitors (particularly the ones inside a know brand IEC socket - 
>>> filter)
>>> caught fire.
>>> Wikipedia says that several areas in UK still have 250 V because this
>>> value is withing the current limits.
>>> I think that the governing document is British Standard BS 7697: 
>>> Nominal
>>> voltages for low voltage public electricity supply systems —
>>> (Implementation of HD 472 S1).
>>> Regards,
>>> Ignacio, EB4APL
>> Hi,
>> I have just been on to the phone of a friend of mine who spent much 
>> of his
>> like working in the electricity generating industry. Working at both
>> Darlington (coal) and Bradwell (nuclear) power stations in the UK. Among
>> many other things he said
>> * He did not know the current specifications limits for certain, but he
>> said easy to check. (What you say - 230 -6%/+10% does seem to be 
>> quoted in
>> many places, but I guess I should check it out.)
>> * Supply voltage is likely to be highest about at 2-3 am in Summer
>> * Supply voltage is likely to be lowest on a cold Winter's afternoon.
>> * Voltages in use around the county include at the least 11, 22, 33, 66,
>> 132, 275 and 400 kV.
>> * There's not much standardization of generator voltage - Bradwell 
>> nuclear
>> power station was 11.1 kV.
>> * There are taps on the 275 kV transformers to keep the 132 kV close 
>> to 132
>> kV
>> * There are 6 taps on the 11 kV transformers feeding my house to 
>> adjust the
>> voltage. Those can only be adjusted with the 11 kV off - they can't 
>> be done
>> with it online. Essentially this means to change the taps, an area would
>> need to be powered off.
>> * If voltage is out of spec, it should be possible to get something done
>> about it.
>> * The electricity board can install monitor equipment.
>> * Since I am right by the 11 kV transformer, and other places further 
>> away,
>> dropping the voltage at my place might put other places too low.
>> I think short-term I will put the auto transformer in line. I will 
>> monitor
>> the mains, and report it in the summer, when I'm told it is likely to go
>> higher.
>> It hit 250.04 V in the last hour or so, but I have not seen the magic
>> figure of 253 V.
>> I'll get my 3457A calibrated by Keysight, then look to measure this 
>> and if
>> appropriate make a formal request to have the voltage checked, and
>> hopefully the problems would occur during the time it was monitored.
>> Dave
>> _______________________________________________
> There are some devices that benefit from the higher voltage. Motors 
> usually run cooler and last longer due to the lower I2R losses.
> Maybe just use a buck transformer in your lab for the (older) test 
> equipment.

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