[time-nuts] Anyone (ideally in the UK) got a spare rotary knob for the 5370B TI counter?

Adrian Godwin artgodwin at gmail.com
Sat Dec 31 22:06:41 UTC 2016


David,

You're a volt-nut too, aren't you ?
Maybe motorise the variac and keep your lab at 240V +/- almost-nothing ?


On Sat, Dec 31, 2016 at 7:57 PM, Tom Miller <tmiller11147 at verizon.net>
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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