Generally you see transformers for EU rated at 220/230V AC, this I guess is to achieve a general standard to suit European mains and please most people.
Here, certainly in my area we get 238 - 243 V AC all the time, as you know the mains vary according to time of day.
So - Is it certainly better to ask for 240V AC primaries on my new toroid?
Can someone tell me the difference this would have to the secondary voltages, the extra 10V AC would manifest as a slight increase to the same secondary voltage if found on a 230V AC toroid?
For instance: a 230v AC with 32V secondary would give 1.414 x 32 = 45.2V
How would this compare to a 240v AC with 32V secondary? Is it as simple as increasing by 4.3% (percentage of 10 of 230)?
Hope this is clear, this for Toriody who generally offer 230V primaries.
Here, certainly in my area we get 238 - 243 V AC all the time, as you know the mains vary according to time of day.
So - Is it certainly better to ask for 240V AC primaries on my new toroid?
Can someone tell me the difference this would have to the secondary voltages, the extra 10V AC would manifest as a slight increase to the same secondary voltage if found on a 230V AC toroid?
For instance: a 230v AC with 32V secondary would give 1.414 x 32 = 45.2V
How would this compare to a 240v AC with 32V secondary? Is it as simple as increasing by 4.3% (percentage of 10 of 230)?
Hope this is clear, this for Toriody who generally offer 230V primaries.
The ratio of primary to secondary voltages remains constant, when the line varies.
If you can choose the primary for your exact line voltage, so much the better.
> a 230v AC with 32V secondary ... compare to a 240v AC with 32V secondary?
Yes, just ratio it out, as Rayma says.
A "stock" and IDEAL "230:32" fed 240V would give 33.4V. 238-243 gives 33 to 33.8. This much variation should be zero problem.
A REAL transformer sags to the rated voltage at Full Load, and will be 2% to 20% higher No Load. Small iron un-sags more than big iron. A 10VA "32V" winding may be near 38V when un-loaded.
Do NOT feed more than 15% over-voltage. A "230" should not eat 265V unless you consult with the maker. You are far from that point. (UK may be over 230V but they know nominal 230V gear must work smokelessly or there will be complaints.)
1.414 never quite happens. As said you get more when tested no-load. You lose 1V in rectifier. At heavy DC load there will be 1%-10% ripple, so the average (DC meter) is less than the Peak, and the ripple-dips (amp clipping) even less than that. Design so much slop is tolerable. i.e. do not figure to put 45V on a 45V chip/device because it may be 52V idle and 38V clip-notches.
Yes, just ratio it out, as Rayma says.
A "stock" and IDEAL "230:32" fed 240V would give 33.4V. 238-243 gives 33 to 33.8. This much variation should be zero problem.
A REAL transformer sags to the rated voltage at Full Load, and will be 2% to 20% higher No Load. Small iron un-sags more than big iron. A 10VA "32V" winding may be near 38V when un-loaded.
Do NOT feed more than 15% over-voltage. A "230" should not eat 265V unless you consult with the maker. You are far from that point. (UK may be over 230V but they know nominal 230V gear must work smokelessly or there will be complaints.)
1.414 never quite happens. As said you get more when tested no-load. You lose 1V in rectifier. At heavy DC load there will be 1%-10% ripple, so the average (DC meter) is less than the Peak, and the ripple-dips (amp clipping) even less than that. Design so much slop is tolerable. i.e. do not figure to put 45V on a 45V chip/device because it may be 52V idle and 38V clip-notches.
220/230V is a compromise to suit most possible customers.
IF you have a **Custom wound** transformer, by all means have it specc´d for your real mains voltage available, whatever it is.
After all, you are paying extra for it, waiting extra time, etc. , so why not?
IF you have a **Custom wound** transformer, by all means have it specc´d for your real mains voltage available, whatever it is.
After all, you are paying extra for it, waiting extra time, etc. , so why not?
no, I don't think you need to have 240V spec
230V will do, unless your AC goes as high as 255V like in Australia in some places
230V will do, unless your AC goes as high as 255V like in Australia in some places
The EU 'harmonized' mains voltage at 230V by sleight of hand. In practice the UK is still 240V and is likely to stay there, with perhaps a very slow drift upwards. My guess is that most of the rest of Europe is still 220V, but with a faster drift upwards. Electricity suppliers like higher voltages, as they can supply more power (which they get paid for) using less current (which they have to pay for, in terms of thicker cables).
A 230V transformer should be OK in the UK, provided it is not too cheap. Running unloaded is most likely to cause saturation. If specifying the transformer yourself, I would go for 240V unless you know your mains is normally lower than this.
A 230V transformer should be OK in the UK, provided it is not too cheap. Running unloaded is most likely to cause saturation. If specifying the transformer yourself, I would go for 240V unless you know your mains is normally lower than this.
Many thanks for the answers guys. I get it... 230V is no real problem but I will certainly ask for 240V.
Gold old Terry Monaghan at Canterbury Windings makes UK trafo's at 240V as standard unless asked otherwise. He is off his feet right now bless him.
Load and no load voltages at secondaries is something I forget about.
Gold old Terry Monaghan at Canterbury Windings makes UK trafo's at 240V as standard unless asked otherwise. He is off his feet right now bless him.
Load and no load voltages at secondaries is something I forget about.
Actually just got off the phone to Terry Monaghan. He will be clear for orders very soon, possibly later this month.
About one month lead time for custom orders, I simply cannot recommend his work enough. He will make anything especially to certain size constraints or practically any dimension to suit you. He is a rare breed these days.
So I will send my order and go with him. All good in the end.
Thanks again people.
About one month lead time for custom orders, I simply cannot recommend his work enough. He will make anything especially to certain size constraints or practically any dimension to suit you. He is a rare breed these days.
So I will send my order and go with him. All good in the end.
Thanks again people.
Yes make that one 240V and maybe it is even better to have it suitable for 250V. There are plans for years now to up the EU voltage to 250V. Less losses, more green, more profit, new impulse for people to renew devices, etc. UK regulations already specify 230 volts +10% - 6% (ie. between 216.2 volts and 253 volts),!!!
Maybe it is exxagerated but it costs practically nothing extra to have it wound for 250V and there is no negative effect. I recall many 220V transformers humming at 230V when that change happened. They mostly ended up in the bin. The devices that had selectable 240V windings for the UK survived.
BTW EU transformers are not rated 220/230V anymore as the 220V standard was abandoned more than 25 years ago. It is 230V.
Maybe it is exxagerated but it costs practically nothing extra to have it wound for 250V and there is no negative effect. I recall many 220V transformers humming at 230V when that change happened. They mostly ended up in the bin. The devices that had selectable 240V windings for the UK survived.
BTW EU transformers are not rated 220/230V anymore as the 220V standard was abandoned more than 25 years ago. It is 230V.
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In Portugal nominal Voltage is 230V for L-N and 400V for R-S-T, but was 220V & 380V years ago, and I haven't changed transformers. I guess gear should handle up to 250V
I wonder how older electronic would hold up with going up to 250V. And if you then still have those 10% up, that could start being a problem
Now that was a long time ago! It has been tens of years that the phases are called L1, L2 and L3 🙂 It is not something a normal citizen notices. 15 years after the change to 230V I still noticed devices that had selectable mains voltage to be set to 220V... People here still call mains voltage "two-twenty"....
My suggestion to have a new transformer wound for 250V is because it does not make it noticable more expensive and mains voltage is already often higher than 235V. A little bit more headroom for the primary winding won't hurt while a too tight wound primary winding does have drawbacks. The change from 220V to 230V immediately made clear that many manufacturers had too tightly specified mains transformers. Consumer stuff -> make it cheaper wherever you can.
I knew the numbers from the change to 230V here but I forgot. I only recall light bulbs having a shorter lifespan (cut by almost 50% when mains voltage is 10V higher). Electronic stuff that still has the original electrolytic caps won't live long when mains voltage is upped. As consumers we are supposed to buy new stuff and not continue with gear that is 20+ years old 😉
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> People here still call mains voltage "two-twenty"....
My "One-Ten" is a solid 125V 364 days a year. On the hottest day it might dip to 124V.
(That's at the street. I'm too far back, my line is long. I get 121 a lot, but can see 108V on laundry day when all the "Two-Twenty" loads run.)
My "One-Ten" is a solid 125V 364 days a year. On the hottest day it might dip to 124V.
(That's at the street. I'm too far back, my line is long. I get 121 a lot, but can see 108V on laundry day when all the "Two-Twenty" loads run.)
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