I didn't assume. By definition a transformer IS a wire wound component.
Xmas Lights Transformer
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I didn't assume. By definition a transformer IS a wire wound component.
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Most switch mode power supplies and most DC power supplies contain as their main component a wire wound transformer, and they transform 230 volt into a lower voltage with some current limit. What is inside the black plastic case does not interest the user, nor does what it is called, switch mode power supply, pulse width modulated power supply, battery eliminator, driver, or transformer it does not matter.
All that matters is AC or DC, voltage or current regulated, voltage output and current output.
All that matters is AC or DC, voltage or current regulated, voltage output and current output.
Switch mode power supplies do indeed include a small transformer, but I would hardly call it a main component. While what is inside the case (which is not always black or plastic) may not interest the user, it is important he/she refers to it by its correct name. A transformer is a wire wound component that always produces an AC output without changing frequency. A switch mode power supply produces a stabilised supply which can be DC or AC often at a far higher frequency than the input frequency.
You did assume - you assumed that the OP was using terminology in the traditional (which you would call 'only correct') manner, despite the fact that we know (even if you/we don't like it) that a substantial, probably high, proportion of the general public (not to mention many parts of the industry) do not use 'correct' terminology.
Assuming is always dangerous, particularly when there is a substantial probability of the assumption being wrong!
Kind Regards, John
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I don't think the assumption was wrong. Xmas lights are not usually run from switch mode supplies, and switch mode supplies are never quoted with a VA rating?
People should, no must, use the correct terminology. To do otherwise is asking for problems.
We all know the industry don't know what they are talking about. We had an example earlier this evening with GU 5.3 lamps referred to as MR16. Other common errors are "plugtops", and "digital aerials".
However we as professionals should know better. It seems, sadly, this is not always the case.
Some even use electricity to allow them to transform, so today as you say you do need to specify the type of transformer, missing out "wire wire wound" is as bad as missing out "electronic" one should never assume. A transformer is NOT by definition wire wound, you need to specify that like any other feature like iron core etc.
There is NO SUCH THING as an "electronic transformer". It is just another incorrect term used in the industry like "plug tops" and "digital aerials".
We as professionals should know better.
Definition of transformer:
https://en.m.wikipedia.org/wiki/Transformer
I THOUGHT ADMIN WARNED WINSTON1 ABOUT THIS POINTLESS TRANSFORMER CHIRADE
im sure a 3.6va or a 6va wire wound transformer does not even exist
im sure a 3.6va or a 6va wire wound transformer does not even exist
3VA and 6VA relate to size of transformers, they do exist and they come in as many voltages as one wants, you can buy a 3VA in 0-6v, 0-9v, 0-12v , 0-15v. 0-18v, 0-24v and same again in other VA ratings, as the VA ratings go up, so does its physical size. In simple terms 3VA means maximum 3 watts, 6VA means 6watts maximum.
Now the VA confusion, it simply means the product of voltage and current, so a 3VA transformer with 12v output can provide 250mA load current, that means it will provide a maximum safe continuous power of 3 watts, or 250mA at 12volts, but the same 12v rated transformer cannot provide 500mA at 6volts because it is rated at 12v and not 6volts, so even if you were able to reduce the 12v to 6v by means of a voltage regulator or a resistor, you cannot obtain 500mA as it was wound with a wire that cannot supply 500mA, but only 250mA or less at 12v, so this transformer will only be able to supply 250mA at all voltages up to 12v.
However a 3VA transformer rated at 6volts will be able to supply continuously 500mA at 6volts because its windings are rated at 500mA and terminal voltage rated at 6volts, but it is still a 3VA transformer, that means physically all 3VA transformers with different voltages will have same physical size. They will look similar from the same manufacturer.
Always better to use a higher rating than needed, so using a 6VA transformer instead of a 3VA and 3.6VA is much more safer and will run cooler as long as the replacement transformer has the same voltage as the original.
Proof they do exist: https://www.rapidonline.com/Catalogue/Searches?query=3va transformer&filterSearchScope=1
Now, now, now, who is the naughty boy using only 3.6watts for a Christmas lights! you need bigger tree and more power for a brighter Christmas!
must be a tiny Christmas tree!
Now the VA confusion, it simply means the product of voltage and current, so a 3VA transformer with 12v output can provide 250mA load current, that means it will provide a maximum safe continuous power of 3 watts, or 250mA at 12volts, but the same 12v rated transformer cannot provide 500mA at 6volts because it is rated at 12v and not 6volts, so even if you were able to reduce the 12v to 6v by means of a voltage regulator or a resistor, you cannot obtain 500mA as it was wound with a wire that cannot supply 500mA, but only 250mA or less at 12v, so this transformer will only be able to supply 250mA at all voltages up to 12v.
However a 3VA transformer rated at 6volts will be able to supply continuously 500mA at 6volts because its windings are rated at 500mA and terminal voltage rated at 6volts, but it is still a 3VA transformer, that means physically all 3VA transformers with different voltages will have same physical size. They will look similar from the same manufacturer.
Always better to use a higher rating than needed, so using a 6VA transformer instead of a 3VA and 3.6VA is much more safer and will run cooler as long as the replacement transformer has the same voltage as the original.
Proof they do exist: https://www.rapidonline.com/Catalogue/Searches?query=3va transformer&filterSearchScope=1
Now, now, now, who is the naughty boy using only 3.6watts for a Christmas lights! you need bigger tree and more power for a brighter Christmas!
must be a tiny Christmas tree!
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More or less correct but VA and watts are not the same thing except for resistive loads. It is quite possible to have a 6VA load with zero watts, a purely capacitive load for example.
Watts = VA x power factor.
Watts = VA x power factor.
Not correct. They are the same for any load with a unity power factor.
True.
Perhaps more to the point, although I agree that ratings are not usually expressed as VA other than for wire-wound transformers, I don't think that there is anything conceptually wrong with using VA (rather than Watts) for any sort of power source, even a DC one (in the latter case inevitably the same as Watts).
Kind Regards, John
Bearing in mind OP's load being Christmas lights, assuming they are LEDs, then they are more or less restive load, if they were incandescent bulbs, again they are almost like a resistor in behavior once lit up, only initially they may present an inductive load drawing 10 times as much current for a split second which rarely effects VA rating of a transformer for momentary overloading.
I agree with Winston that VA rating may exceed if one was continuously using inductive loads as opposed to resistive loads. Inductive loads such as electric motors or drills etc, especially under heavy mechanical loading the electrical power may well exceed many times the rated safe power of both the appliance and the transformer rating, a stalled electric motor can exceed the power rating of a transformer and cause overheat or burn it out as well as itself it can overheat.
So the conclusion is OP asked if he replaces his 3.6VA transformer with a 6VA, as long as his output voltage is also the same , yes it is a better option if anything, probably the manufacturer supplied barely enough power rated transformer to keep his costs down hence why it probably packed up, at the same time one would not really order a transformer that was rated much too higher for his application, so no point using a 100VA transformer for a load that is specified as 3VA, its like taking a Juggernaut on a camping holiday when all you need is a camper van instead of a mini.
I agree with Winston that VA rating may exceed if one was continuously using inductive loads as opposed to resistive loads. Inductive loads such as electric motors or drills etc, especially under heavy mechanical loading the electrical power may well exceed many times the rated safe power of both the appliance and the transformer rating, a stalled electric motor can exceed the power rating of a transformer and cause overheat or burn it out as well as itself it can overheat.
So the conclusion is OP asked if he replaces his 3.6VA transformer with a 6VA, as long as his output voltage is also the same , yes it is a better option if anything, probably the manufacturer supplied barely enough power rated transformer to keep his costs down hence why it probably packed up, at the same time one would not really order a transformer that was rated much too higher for his application, so no point using a 100VA transformer for a load that is specified as 3VA, its like taking a Juggernaut on a camping holiday when all you need is a camper van instead of a mini.
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Generally true but it is not that simple when the power is supplying inductive loads and capacitive loads that are balanced to provide a power factor of approx 1.
I don't really understand. That is surely precisely the situation in which Watts and VA can be roughly (or even exactly) the same despite the load being non-resistive (or, at least, not entirely resistive). In what sense do you think that it is 'not that simple'? - I would have said that winston's formula for the relationship between watts, VA and PF always holds, essentially 'by definition'.
Kind Regards, John
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