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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 6th Jul 2013, 6:41 pm   #1
crusher19860138
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Wink AC Mains Voltages

Hello ,having just restored a DAC90A for a relative who lives 'out in the sticks', iI returned the set to them,and whilst I was there,decided to check the mains input voltage as they are quite a way from the nearest town, it measured in at 231 volts! so I set the voltage tapping at 230V in the back of the set as I had set it to 250V because where I live, the mains measures at 253V!

What is the supply voltage where you are and are wide differences like those above commonplace in the UK?
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Old 6th Jul 2013, 7:11 pm   #2
GrimJosef
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Default Re: AC Mains Voltages

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Originally Posted by crusher19860138 View Post
Hello,having just restored a DAC90A for a relative who lives 'out in the sticks',i returned the set to them,and whilst i was there,decided to check the mains input voltage as they are quite a way from the nearest town,it measured in at 231 volts!,so i set the voltage tapping at 230V in the back of the set as i had set it to 250V because where i live,the mains measures at 253V!

What is the supply voltage where you are?and are wide differences like those above commonplace in the UK?
Be a bit careful. As well as differences from place to place we also suffer from differences from time to time. If you happened to catch your relative's mains at an unusually low moment you may find that it has since recovered and the radio is now being fed by more like 240V. As a general rule the mains in my workshop varies from about 237V to 245V. But I've seen it at 235V and also at 248V, and I don't check very often so these can't be really freak readings.

Mrs GJ was (ahem) 'a few decades ago' a student sponsored by the then Central Electricity Generating Board. She spent a summer working for them and got to learn some of the ins-and-outs of the system's operation. She once told me that demand variations were dealt with by a combination of letting the voltage drift and letting the frequency drift. The relative importance of the two varied from country to country and in the UK we worked hard to keep the frequency steady which meant we let the voltage flap about quite a bit. The French, for example, tended to do the opposite. A lot may have changed since then. But this is a pretty fundamental issue and I wouldn't be surprised to learn that the practice now is the same as it's always been. That would explain the poor standard of voltage stability that I, for one, have to live with.

Cheers,

GJ
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Old 6th Jul 2013, 7:35 pm   #3
TrevorG3VLF
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Default Re: AC Mains Voltages

I made a note of the required voltage some time ago, whether it still applies I know not.

230V +10% -6%
i.e. 216.2V to 253V

I never did understand why dropping the frequency drops the power, certainly fluorescent lights will consume more.

Trevor
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Old 6th Jul 2013, 7:41 pm   #4
paulsherwin
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Default Re: AC Mains Voltages

Rural housing can be at the end of a long low voltage circuit. They often don't have mains gas supplies, and when everybody turns their ovens and washing machines on in the evening the voltage can drop quite low. I once stayed in a remote cottage in Sussex and the lighting would dim dramatically when the oven thermostat switched.

It's usually best to set mains selectors to 240V in the UK unless you have a very good reason to do otherwise.
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Old 6th Jul 2013, 8:31 pm   #5
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Default Re: AC Mains Voltages

What it should be: The Electricity Supply Quality and Continuity Regulations 2002, (http://www.legislation.gov.uk/uksi/2002/2665/made)

Paragraph 27:

(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 affected) 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;

If your mains supply is outside these limits you would have a good case for a complaint to the supplier.

PMM
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Old 6th Jul 2013, 8:53 pm   #6
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Default Re: AC Mains Voltages

Well, yes, but that's not much help if your prized valve radio has been knackered because you set the voltage tapping to 230V and the supply goes to 255V in the afternoon when everybody turns their appliances off.

Life is much easier in urban areas where the voltage varies very little.
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Old 6th Jul 2013, 9:31 pm   #7
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Default Re: AC Mains Voltages

Tedious as it sounds, it is worth keeping an eye on trends with a respectable AC meter and setting voltage selection, the variation might seem trivial but some consequences can be disproportionate. It's not at all unusual for output valve screen grid to be fed more or less directly from the main HT rail, i.e. from low source resistance. As HT goes up, so does screen volts- therefore likely anode current. More volts x more milliamps= rather more heat, and many output valves run a bit on the edge at the best of times. Also, high quality radios may have shunt regulators- say we have a 150V stabiliser designed to be fed with 250V HT, i.e. 100V across its feed resistor. HT unfortunately is actually 270V- that's 20% more current through the feed resistor, more heat and more for the stabiliser to cope with.
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Old 7th Jul 2013, 1:17 am   #8
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Default Re: AC Mains Voltages

Does it hurt a radio, tv or similar electronics to be under-run regarding voltage? I am talking reasonable deviation, such as ten volts approx.
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Old 7th Jul 2013, 8:49 am   #9
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Default Re: AC Mains Voltages

There is a unit which is available now to regulate the voltage to your house supply. I have one fitted, and it's set to 230v. It's called a V-Phase unit, and here is a link to their site http://www.vphase.co.uk/
As well as a stabilised power supply; the idea is that it will save electricity by only using 230v instead of 240-250v
I've had mine for about a year now, and there is no need for seperate stabilised power supplies for computer equipment, or anything else which might be sensitive to voltage spikes.
I hope this has been of some help.

Regards

Ralph.
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Old 7th Jul 2013, 9:50 am   #10
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Default Re: AC Mains Voltages

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the idea is that it will save electricity by only using 230v instead of 240-250v
Doubtful at best, good idea for the radios, it uses a large torroidal transformer the output of which is put in antiphase series with the incomming mains. Not sure how it controls the output of the transformer.
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Old 7th Jul 2013, 10:06 am   #11
matthewhouse
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Default Re: AC Mains Voltages

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..the idea is that it will save electricity by only using 230v instead of 240-250v
It's 220V out not 230V, though I see this can be changed by buying optional jumpers. I've never seen one installed, they are designed to connect to only some of the circuits. If you are really having problems with voltage variation, automatic variacs are available cheap second hand for connecting small appliances. Most are adjustable internally to set the output voltage you want. I have seen a mains supply to a house at about 262V, the resident of the house complained that light bulbs failed often and certain appliances also had short lives.

Last edited by matthewhouse; 7th Jul 2013 at 10:15 am.
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Old 7th Jul 2013, 10:19 am   #12
ralph2472
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Default Re: AC Mains Voltages

Mine is set at 230v and supplies everything in the house.

Regards

Ralph.
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Old 7th Jul 2013, 10:38 am   #13
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Default Re: AC Mains Voltages

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Originally Posted by TrevorG3VLF View Post
I made a note of the required voltage some time ago, whether it still applies I know not.

230V +10% -6%
i.e. 216.2V to 253V
If you look at this you will see that it is in fact tweaked around 240 Volts nominal. 230 volts as a perceived UK standard was only adopted because to comply with EU regs . In reality the UK network was designed and set up for 240 volts nominal and all LV transformers supplying customers are set on 240 volts per phase delivered to the customer. In reality if there is very little load the volts go up slightly whilst if heavily loaded they go down. If you are on a long bit of rural damp string you have to add in the resistance as well. Thus the volts will be lower but theoretically still above the 216 volts. I live in rural Lincolnshire and have my own pole transormer. My voltage is nearly always 253 and most modern kit is designed to cope with this.
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Old 7th Jul 2013, 10:44 am   #14
crusher19860138
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Default Re: AC Mains Voltages

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Originally Posted by paulsherwin View Post
Well, yes, but that's not much help if your prized valve radio has been knackered because you set the voltage tapping to 230V and the supply goes to 255V in the afternoon when everybody turns their appliances off.

Life is much easier in urban areas where the voltage varies very little.
My relative is an electrical engineer,and tells me that the AC mains into his property rarely goes above 235V, mostly hovers around 230V ,so I am happy to leave the voltage setting at 230V.
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Old 7th Jul 2013, 10:48 am   #15
crusher19860138
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Quote:
Originally Posted by ralph2472 View Post
..the idea is that it will save electricity by only using 230v instead of 240-250v
It's 220V out not 230V, though I see this can be changed by buying optional jumpers. I've never seen one installed, they are designed to connect to only some of the circuits. If you are really having problems with voltage variation, automatic variacs are available cheap second hand for connecting small appliances. Most are adjustable internally to set the output voltage you want. I have seen a mains supply to a house at about 262V, the resident of the house complained that light bulbs failed often and certain appliances also had short lives.
262V? Now that is too high!
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Old 7th Jul 2013, 1:06 pm   #16
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Default Re: AC Mains Voltages

In a way, I'm lucky in that my mains on the edge of London tends between 225-232V (traceable Fluke 83), with an occasional giddy surge towards 235V- all quite benign, really. If it's significantly and consistently above 240V, it could be simply and efficiently "bucked" by 10V or so with an appropriate transformer- it won't correct the range of the variation but it will shift the centre-point. You could have a separate "vintage" feed.
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Old 7th Jul 2013, 3:13 pm   #17
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Default Re: AC Mains Voltages

I just checked the voltage on one of my sockets and got a reading of 227v
I used to have the exploding light bulb problem; but not any more. I've now changed all my lights to low energy ones now so that problem shouldn't happen anyway.
I was told by the installation electrician that all modern appliances must be able to run correctly on 220v. I have some old appliances, and they seem to be coping o.k. on the lower than 240v supply that they were designed for.
My T.V. is an old 21" Matsui 2096R CRT model, and that works perfectly.
My radio is an even older Fergusson 388A.

Regards

Ralph

Last edited by ralph2472; 7th Jul 2013 at 3:15 pm. Reason: addition
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Old 8th Jul 2013, 2:02 pm   #18
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Default Re: AC Mains Voltages

Our voltage has always been on the high side - it normally hovers between 248V and 251V.

Once I nearly found this out the hard way, when I used a Uher tape recorder mains adapter that had been set on the voltage dial to the 230V position. After about a minute it had heated up to such an extent it was not possible to hold it.

Suffice to say it was promptly disconnected and changed to the 250V setting, with no further problems or heating.

I now always make sure where appliances have a mains adjustment setting it is always set at least to 240V!, and on some older appliances where there is an additional setting 0f 250V - set it to that.

Out of interest we live only 60 feet away from an electricity substation.

Ian.
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Old 8th Jul 2013, 6:22 pm   #19
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Default Re: AC Mains Voltages

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Originally Posted by Hampus1982 View Post
Does it hurt a radio, tv or similar electronics to be under-run regarding voltage? I am talking reasonable deviation, such as ten volts approx.
Probably not. Significantly under-run (20% or more) is a different story though. And the same could apply to reasonably modern electronic equipment too.
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Old 8th Jul 2013, 6:59 pm   #20
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Default Re: AC Mains Voltages

One thing that doesn't like to be underrun is heating. We have electric heating using a Nightstor boiler, and when the volts drop from 250 to 225 it can't charge overnight. Have wondered about a stabiliser but it does take 80A or so. And we are only about 100' from the 11kV transformer.
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