Frequency limits for the equipment

[Electrical]

What is the operating limit for which electronic devices work properly? In the US we see it is 60 Hz and in other parts of the world it is 50 Hz, so what are the upper and lower limits for which a device can operate properly?

[Strange]

That is the frequency of the electrical supply expected by the power supply. I just checked the data sheet for a random switched-mode power supply and it was specified for 47 to 63 Hz. I would guess this is typical as there is no reason to work at any other frequency. It would probably work outside that range but possibly with reduced efficiency.

[John Cuthber]

For special purposes (In aviation) the range also includes about 400 Hz

[Enthalpy]

Some boats have 400Hz too. Trains get electricity at 25Hz in Switzerland and 16Hz2/3 in Germany. Other parts of the world have other frequencies than 50Hz and 60Hz.

Just for fun (when you're not involved): Japan has (or had) different electricity systems among the islands.

And for fun too: The Itaipú dam produces electricity, 50% for Brasil and 50% for Paraguay. But since Paraguay covers all its needs with 2% of the production, it sells the rest to power-hungry Brasl. Of course, to let Brasil pay, the switch and power meter are located in Paraguay, so the current first goes there, then crosses back. Little difficulty : Brasil has its current at 60Hz there but Paraguay at 50Hz and the 10 alternators from 20 match. The choice was to transport everything in DC to São Paulo.

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Frequency limits: for a computer power supply, no worry. The input is a resonating circuit that often guarantees both frequencies and voltages. Most electronic equipment won't see the difference.

But electromagnetic machines do make the difference, because d(phi)/dt depends on F. A transformer for 60Hz may over-saturate its iron core at 50Hz hence draw too much current. A synchronous or asynchronous motor runs at the wrong speed, and this changes the counter-electromotive force, which may not match the main's voltage.

[John Cuthber]

Electrical power is traded between the UK and France- in spite of the fact that we use 50 Hz and they use 60.
It's converted to DC for transmission under the channel. It has the side benefit of being more economical to do that for some cases (and this is one of them).

 

[studiot]

2 minutes ago, John Cuthber said:

Electrical power is traded between the UK and France- in spite of the fact that we use 50 Hz and they use 60.
It's converted to DC for transmission under the channel. It has the side benefit of being more economical to do that for some cases (and this is one of them).

 

Please check this

https://www.google.co.uk/search?q=mains+frequency+in+France&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&dcr=0&ei=N9_wWYu4H6bHXsSZuIgF

The EU (ie French) standard is 230 volts 50 Hz.

I'm willing to believe that they have some oddities over there as well.

[John Cuthber]

5 minutes ago, studiot said:

Please check this

https://www.google.co.uk/search?q=mains+frequency+in+France&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&dcr=0&ei=N9_wWYu4H6bHXsSZuIgF

The EU (ie French) standard is 230 volts 50 Hz.

I'm willing to believe that they have some oddities over there as well.

Oops!

the transfer is still DC.

Does anyone know if the UK grid is synchronised with the rest of Europe?

If not, that might have been part of the original reason for using DC.

[studiot]

45 minutes ago, John Cuthber said:

Oops!

the transfer is still DC.

Does anyone know if the UK grid is synchronised with the rest of Europe?

If not, that might have been part of the original reason for using DC.

Yes high voltage DC transmission through special cables can be more efficient than AC, especially underwater.

I think there is one in New York under the Hudson.

 

What do you mean by synchronised?

The UK electrical power standards had to be dumbed down to meet the EU requirements.

They were by far the best in Europe.

 

 

[John Cuthber]

Our mains supply is nominally 50Hz and it's very close to it, but it varies slightly.

You can monitor it if you get bored

http://www2.nationalgrid.com/uk/services/balancing-services/frequency-response/

But all the power stations in the UK run at the same  frequency at any given time.

Presumably the French grid does the same.

But are the two grids synchronised to eachother?

 

[studiot]

1 hour ago, John Cuthber said:

Our mains supply is nominally 50Hz and it's very close to it, but it varies slightly.

You can monitor it if you get bored

http://www2.nationalgrid.com/uk/services/balancing-services/frequency-response/

But all the power stations in the UK run at the same  frequency at any given time.

Presumably the French grid does the same.

But are the two grids synchronised to eachother?

 

"But are the two grids synchronised to each other?

I'm sorry I don't know what you mean by synchronised. That is why I asked.

Both systems are poly phase at intermediate voltage, single phase at very high voltage and poly or single phase at supply voltage.
But are you asking if the sine waves match?
Well the phase of the waves will depend upon where you take measurements. It is over 1,000 miles direct from Aberdeen to Marseille and the phase can change according to the travel distance and intervening transformers.
 

The history of the mains stability is worthy of mention.

In the days before all the (portable) clever electronic gadgets we have nowadays, important timekeeping was kept by counting mains cycles.
This was so important that the power supply acts included very strict requirements on the accuracy and stability of the mains frequency.

Clocks for railway stations signalling, points etc, works time clocks for clocking on and off, post office clocks, etc etc were all mains driven.

Th issue is that one way of controlling (reducing) supply when demand is too high is to reduce the frequency.

Today the power companies have to maintain the correct number of cycles over a 24 hour period, but can reduce frequency at say tea or breakfast time and increase in the night.

Edited October 25, 2017 by studiot

[Enthalpy]

Not the sought answer, sorry...

On the European continent, the networks are synchronized, and because transmission delays shift the phase, 3-phase transformers with extra windings adjust the phase for smooth connection. That is, to phase A add the proper amount of phase B or C to get in-phase with the rest of the grid.

DC under the channel because of the stray capacitance. I can't tell if the 3-phase grids are synchronized between the British Isles and the continent. DC is also better over long distances against ohmic losses and becomes easier presently in the GW and MV range; in the 70's for Itaipu it was badly difficult.

Presently, offshore wind turbines transmit a few MW with DC for the same reason. It's even more meaningful because modern wind turbines run at variable speed (less variable than wind speed) so they make DC at some step.

[studiot]

Good answer, Enthalpy and much shorter than mine.

+1

[John Cuthber]

On 10/25/2017 at 10:55 PM, studiot said:

Well the phase of the waves will depend upon where you take measurements. It is over 1,000 miles direct from Aberdeen to Marseille and the phase can change according to the travel distance and intervening transformers.

All the way from Aberdeen to land's end they will be in synchrony.
From Calais to Gibraltar they will be in synchrony.

They grids have to be in lock step with themselves.

 

But is the French mains in synch with ours?