Wow, confusing ..so what will be the best rate for 220v@50Hz?
I really wondering if a AC regenator will not be the solution, isn't it?
there is dc on you lines, that is why your toroids bussed...
toroids are easily persuaded to saturate due the the high flux density they
are made to run on....
do a search of the forums on how to solve this problem...
then it is time to use EI cored traffos...
other people's homes uses microwave ovens some appliances
may use thyristor power controllers.....
you can not do anything about these if they are outside your house
and in your neighbor's.....
or maybe a power isolation traffo big enough for your gears....
other people's homes uses microwave ovens some appliances
may use thyristor power controllers.....
you can not do anything about these if they are outside your house
and in your neighbor's.....
or maybe a power isolation traffo big enough for your gears....
Best is to use a transformer rated for a 240 volt 50 Hz primary.
The test is to use a seperate transformers to buck the line voltage down. The good news is that it need not be as large as the power transformer. If I get a chance later I can post the schematic.
I had few gear using those in the past and AFAIR they were the most huming ones.
I will check if they used EI (Promitheus Audio).
Thanks for tips anyway
I will check if they used EI (Promitheus Audio).
Thanks for tips anyway
There is some good advice and lots of inexact one above, basically because most do not know about old (popular in the 30´s , go figure) system "triangle" (might be called Delta in some countries) system of power distribution.
I live in Buenos Aires where large areas of the city were fed using such system.
replaced by now, but I used to live and have my Electronics shop in such a powered house from `76 to ´83 and sometimes had to rely on it as a backup in my current home/shop from ´86 to `95 or so 🙁 .
1) the line is three phase "Triangle/Delta" 3 x 220V , meaning 220V phase to phase, "in theory" 127V phase to neutral, but that depends on line balancing.
2) home wiring is phase to phase so you have good steady 220V BUT both pins are Hot.
No big deal for electrical appliances but in the old days of European 2 round pin plugs (we follow European rules, usually DIN) all amps buzzed a little (unless grounded to a cold water faucet or similar) and all "tingled" a little (same thing).
If anything, it forced me to be very careful with internal grounding, layout, etc.
As they say: "what doesn´t kill you makes you stronger".
3) your toroid primary does not know or care whether it gets 220V phase to phase or phase to ground; if it buzzes it´s most probable that mains waveform is either unsymmetrical (so it has a DC component) or very distorted.
No way you can really solve that, it´s a Power Company problem, out of your reach.
4) if, besides Toroid problems, you want a less noisy system, you might buy a *big* 220:220V transformer (suggest an EI type 😉 ) hook primary Phase to Phase, secondary supplying Phase and Ground. Not sure you want that.
5) nowadays a similar mains distribution system is making a comeback in Brazil, they are replacing old single phase 2 x 110V in series systems, center tap grounded, which can give you both 110V and 220V from the same line, depending on how you wire the outlet (both voltages are in current use there), by way more efficient 3 x 220V Star (is it Wye?) wiring , 3 x 220V *with* a neutral line, so guaranteed 127V phase to ground or 220V phase to phase.
Old amps designed for straight 110V are having big trouble with 127V ; both very high +V and filaments, so a couple entrepreneur guys are selling "brown down" converters "for old equipment", actually 127 to 110V autotransformers.
Back yo your toroids: I doubt you have a *voltage* problem, as mentioned above "modern" 230V is still 220V.
A scope (on the secondary) can show weird waveforms and lack of symmetry.
***Maybe*** you can re-impregnate your toroid and make it less mechanically buzzy.
I live in Buenos Aires where large areas of the city were fed using such system.
replaced by now, but I used to live and have my Electronics shop in such a powered house from `76 to ´83 and sometimes had to rely on it as a backup in my current home/shop from ´86 to `95 or so 🙁 .
1) the line is three phase "Triangle/Delta" 3 x 220V , meaning 220V phase to phase, "in theory" 127V phase to neutral, but that depends on line balancing.
2) home wiring is phase to phase so you have good steady 220V BUT both pins are Hot.
No big deal for electrical appliances but in the old days of European 2 round pin plugs (we follow European rules, usually DIN) all amps buzzed a little (unless grounded to a cold water faucet or similar) and all "tingled" a little (same thing).
If anything, it forced me to be very careful with internal grounding, layout, etc.
As they say: "what doesn´t kill you makes you stronger".
3) your toroid primary does not know or care whether it gets 220V phase to phase or phase to ground; if it buzzes it´s most probable that mains waveform is either unsymmetrical (so it has a DC component) or very distorted.
No way you can really solve that, it´s a Power Company problem, out of your reach.
4) if, besides Toroid problems, you want a less noisy system, you might buy a *big* 220:220V transformer (suggest an EI type 😉 ) hook primary Phase to Phase, secondary supplying Phase and Ground. Not sure you want that.
5) nowadays a similar mains distribution system is making a comeback in Brazil, they are replacing old single phase 2 x 110V in series systems, center tap grounded, which can give you both 110V and 220V from the same line, depending on how you wire the outlet (both voltages are in current use there), by way more efficient 3 x 220V Star (is it Wye?) wiring , 3 x 220V *with* a neutral line, so guaranteed 127V phase to ground or 220V phase to phase.
Old amps designed for straight 110V are having big trouble with 127V ; both very high +V and filaments, so a couple entrepreneur guys are selling "brown down" converters "for old equipment", actually 127 to 110V autotransformers.
Back yo your toroids: I doubt you have a *voltage* problem, as mentioned above "modern" 230V is still 220V.
A scope (on the secondary) can show weird waveforms and lack of symmetry.
***Maybe*** you can re-impregnate your toroid and make it less mechanically buzzy.
a DELTA do not have a neutral but a WYE has, so over here
where line and neutral is used to supply homes....
it is a 380 volt and neutral, so line is 220 volts...
where line and neutral is used to supply homes....
it is a 380 volt and neutral, so line is 220 volts...
Very instructive AJT, I'm reading stuff about DELTA now, thanks.
From what I understand, getting a NEUTRAL will no happen :-(
Stupid question what happens if I connect both phases with ground? I will obtain 254v? Or a fire ;-)
Or if I had the three phases available, I can have a Ov (so the same as NEUTRAL?)
I don't want to do it, I'm just trying to understand...as the sum of three phases should equal O.
From what I understand, getting a NEUTRAL will no happen :-(
Stupid question what happens if I connect both phases with ground? I will obtain 254v? Or a fire ;-)
Or if I had the three phases available, I can have a Ov (so the same as NEUTRAL?)
I don't want to do it, I'm just trying to understand...as the sum of three phases should equal O.
There is no Ebreak because there is a single wire on that node which you can't split. In delta arrangement there is no neutral and you should not try to get one by connecting any phase to ground. You already measured it and any phase has 127VAC to ground. So you will just short it and risk some serious damage if your safety switches aren't quick enough.
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Very instructive AJT, I'm reading stuff about DELTA now, thanks.
From what I understand, getting a NEUTRAL will no happen :-(
Stupid question what happens if I connect both phases with ground? I will obtain 254v? Or a fire ;-)
Or if I had the three phases available, I can have a Ov (so the same as NEUTRAL?)
I don't want to do it, I'm just trying to understand...as the sum of three phases should equal O.
there will be power interruptions when you do that....so don't do it....
in a DELTA, you derive power from two phases...
Ebreak, in a properly connected three phase DELTA, there will be no circulating currents....but you still get your power from two phases, and that will be a balanced lines...
you picture shows how a three phase delta should measure when phasing of the phases are correct, only then can you close it...
other wise if the reading is high, reverse the phase of one leg.
***********************************
That's a "High Leg Delta"
Jim Brown writes about these:
High Leg Delta
BUZZ is nearly always the result of leakage current from the AC power
(mains) system. It can be identified as such because there is very little
50 or 60 Hz, but mostly harmonics. Those harmonics occur because mains
current flows in pulses that recharge the power supply input filter cap,
which causes IR drop to consist of harmonics of 50/60 Hz, causes the mains
voltage to be a distorted sine wave (more IR drop at the top of the
waveform). LOTS of equipment all over the building produces this leakage
current, and more equipment OUTSIDE the building produces this leakage
current.
In 3-phase systems, triplen harmonics ADD in the neutral rather than
cancelling. This is well known. What is NOT well understood is that they
also add in the ground! How does this affect us? In most of the world, the
power system is a 3-phase system, and earth currents from that 3-phase
systems are flowing in places where we don't expect them. An especially
nasty power system connection, called High Leg Delta, uses 240V Delta 3-
phase to feed single-phase power to residences and 3-phase power to
businesses on the same street. That system uses a center-tapped transformer
(at the street) to feed single phase, so WE get two legs of that 3-phase
power plus a neutral. That neutral carries all the ground current, much of
it harmonics, from the 3-phase system!
Neil Muncy first taught me about the mess that High Leg Delta could make in
an audio studio. He was troubleshooting a buzz problem in an urban studio
that he diagnosed as ground currents from that High Leg Delta system going
to ground via a pipe that ran under the studio, almost directly under the
guitar booth. The current created a huge magnetic field that got into
everything.
I live in a somewhat remote area of the Santa Cruz Mountains, and have
single phase 120/240 power, but it's fed from a High Leg Delta system.
There's a lot of buzz current on the neutral that feeds me. I've had to be
quite careful about grounding of the power system to avoid buzz problems.
The buzz is due to the mains, not due to wiring errors. There is nothing you can do about it, other than keep it outside your audio equipment enclosure.
The audio equipment does not need an electrical Protective Earth to work.
It only needs the PE to be safe.
Supply clean isolated DC from the PSU box to the audio enclosure and keep the buzz outside.
The audio equipment does not need an electrical Protective Earth to work.
It only needs the PE to be safe.
Supply clean isolated DC from the PSU box to the audio enclosure and keep the buzz outside.
This is how to do a buck transformer.
I would try this first.
If it has no improvement then buy a power amplifier on eBay and use that with an oscillator to power your equipment. An amplifier rated at a real 1800 watts in the bridged mode 8 ohms will give you 120 volts AC. One really rated at 1500 watts per channel will give you 220 volts when bridged. In theory that should allow a fairly large domestic audio power amplifier to be the load.
You might want to experiment with frequency as some gear works better at a line frequency around 90 Hz.
Some amplifiers have built in DSP and can generate the sine wave without any external gear.
(Jim if the meter is a standard peak reading RMS calibrated meter then when it shows 127 & 127 that means the peaks are symmetric and no DC on the AC offset. A true RMS meter will not show this!)
I would try this first.
If it has no improvement then buy a power amplifier on eBay and use that with an oscillator to power your equipment. An amplifier rated at a real 1800 watts in the bridged mode 8 ohms will give you 120 volts AC. One really rated at 1500 watts per channel will give you 220 volts when bridged. In theory that should allow a fairly large domestic audio power amplifier to be the load.
You might want to experiment with frequency as some gear works better at a line frequency around 90 Hz.
Some amplifiers have built in DSP and can generate the sine wave without any external gear.
(Jim if the meter is a standard peak reading RMS calibrated meter then when it shows 127 & 127 that means the peaks are symmetric and no DC on the AC offset. A true RMS meter will not show this!)
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the wiring of the dual 110:dual 12Vac transformer shown in post57 uses all four windings adding up to 244Vac to give an output of 220Vac.
That 244Vac of total input winding ensures the "primary" can never saturate even when the mains is at top tolerance, 253Vac.
It also means that the output will always be ~ 220/244 = 90% of the input voltage.
i.e. if the actual mains input voltage is at 225Vac, then the output will be at 202Vac
This will lower the risk of mechanical hum/buzz when under heavy load and when the mains is badly contaminated.
That 244Vac of total input winding ensures the "primary" can never saturate even when the mains is at top tolerance, 253Vac.
It also means that the output will always be ~ 220/244 = 90% of the input voltage.
i.e. if the actual mains input voltage is at 225Vac, then the output will be at 202Vac
This will lower the risk of mechanical hum/buzz when under heavy load and when the mains is badly contaminated.
Following on from those two posts.
You are more likely to find new transformers are being built to 230Vac, or dual 115Vac primary.
If you buy a 230:dual 9Vac you have a choice of using one, or both, 9Vac winding in series with the 230Vac Primary.
The total output is the Primary Vac plus the secondary Vac times the rated Secondary current
Thus a 230:9+9Vac 200VA using 248Vac and 11.1Aac (for the secondary) gives an effective VA rating of 2700VA. If that calculation proves to be optimistic, then the Lowest VA rating would be 11.1Aac times 230Vac = ~2500VA
You are more likely to find new transformers are being built to 230Vac, or dual 115Vac primary.
If you buy a 230:dual 9Vac you have a choice of using one, or both, 9Vac winding in series with the 230Vac Primary.
The total output is the Primary Vac plus the secondary Vac times the rated Secondary current
Thus a 230:9+9Vac 200VA using 248Vac and 11.1Aac (for the secondary) gives an effective VA rating of 2700VA. If that calculation proves to be optimistic, then the Lowest VA rating would be 11.1Aac times 230Vac = ~2500VA
Half the transformer loss typically is from the core and half from winding loss, so just doing a ratio gets close but not exact values. Using a standard transformer as an auto transformer as shown will also vary a bit. I like to do at least a 10% reduction as transformers are designed to be a bit into saturation at target voltages as there is that core loss allowance to compensate for it on the output. That makes the variation in output voltage with the mains variations a bit less.
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