Led strips on shelves

[winston1]

Genuine query.

As a matter of interest, Winston, why is that the case?

I realise you are right according to the definition given but could it be that the definition is out of date?

Why cannot something transform 230VAC to 12VDC?
Transform means to change something therefore transformer is merely something that changes something else.
Is your definition just out of date and it has been superseded by the modern world?


If that is out of the question then what does the apparatus do (what verb) when 230VAC goes in and 12VDC comes out?

You can say it is a switched mode power supply but the voltage hasn't been "switch-mode-power-supplied" has it?

A transformer is a device that changes voltage or current by electromagnetic induction. (There is also the special case of a 1:1 transformer used for isolation either of mains or audio circuits). It cannot convert to DC or change the frequency. The definition has not changed but some manufacturers misuse the term. But we know manufacturers (or their marketing people) are ignorant idiots. Other examples of manufacturers stupidity is "digital aerials" and "plugtops".

One device that converts AC to DC is the rectifier. It can also be done with a motor/dynamo set but we would call that a rotary converter rather than a rectifier.

To change voltage and convert to DC would be a power supply. In its simplest form this would contain both a transformer and a rectifier, more complex forms would use electronic switch mode techniques. Can't think of a true verb for this however.

 

[EFLImpudence]

A transformer is a device that changes voltage or current by electromagnetic induction.

Yes, but why? Is that because that was the only method when the definition was written?

After all, definitions of other machines do not include a description of the components or method of operation - just what it does.
Cannot a modern device which achieves the same by 'changing' 230VAC to 12VAC be described as a transformer?
Why can you not have an electronic transformer?

(Conversely: A printer was originally a man with inky fingers who operated a printing press. Now a printer is an electronic device which does not actually print. Also, taking a camera film to the chemist, you may have been asked "How many prints do you want?". They were certainly not 'printed'.)

(There is also the special case of a 1:1 transformer used for isolation either of mains or audio circuits). It cannot convert to DC or change the frequency. The definition has not changed but some manufacturers misuse the term. But we know manufacturers (or their marketing people) are ignorant idiots. Other examples of manufacturers stupidity is "digital aerials" and "plugtops".

Ok.

One device that converts AC to DC is the rectifier. It can also be done with a motor/dynamo set but we would call that a rotary converter rather than a rectifier.

So, why do we not, at least, call them rectifiers?

To change voltage and convert to DC would be a power supply.

Yes, but your 'genuine' transformer supplies power. So does a generator and battery.

In its simplest form this would contain both a transformer and a rectifier, more complex forms would use electronic switch mode techniques.

As it contains a transformer, why can we not call it some different kind of transformer?

Can't think of a true verb for this however.

Perhaps that is the real problem.
There is no word to use if it is not your 'genuine' transformer

 

[winston1]

These modern devices do not achieve the same thing as a transformer. I once tried to use a PWM supply to operate a 12 volt caravan fridge. It didn't work. The load was around 12 volt 8 amp resistive, so well within min/max of the supply. I came to the conclusion that the supply needed an almost short circuit (as provided by a filament lamp) to get started. Or maybe the high frequency was a problem, the fridge heater was after all a wound component with some inductance.

The real problem is that no one has thought of short snappy names for these various devices. Quartz halogen driver, 12 volt DC supply etc don't roll off the tongue. Wallwort is one term sometimes used for supplies built into a mains plug, however this can be anything from a transformer to a switch mode DC supply. Supplies for phones are often called "chargers"

 

[EFLImpudence]

Something which 'changes' 12VDC to 240VAC is an 'inverter', which is just another word which really means something else. Is the voltage turned upside down?
Its definition is an electrical 'converter' - so there we go again.
Unfortunately the opposite of inverter, 240VAC to 12VDC is what? Is that also inverter (turning upside down again) or righter (righting it)?
We can choose any word for it; how about 'transporter'. That won't be confused with anything else.

These words are all badly chosen as they clearly mean something else commonly used as well.

Perhaps there should be a distinction between Transformer (capital T) for your 'genuine' wire-wound chunky lump and transformer (small T) for when people are just using an English word and want something that changes the voltage in some other way.

 

[EFLImpudence]

Of course, I fogot about 'driver'.

What idiot thought of that?

 

[JohnW2]

Of course, I fogot about 'driver'. What idiot thought of that?

Dunno - but its been around for a long time, certainly all my life, in electronic circles - not to mention the more recent usage of the word in relation to computing (and the very long-established meaning in relation to 'driving' screws etc.), quite apart from those who sit behind steering wheels!

I don't want to start off another endless linguistic discussion but, whether we like it or not, and whether it is 'correct; or not, our language is full of 'accepted' examples of words with multiple meanings - in many/most cases at least some of those meanings having been 'added' after whatever was the original one.

Kind Regards, John

 

[EFLImpudence]

That might be the case, but then the converse cannot be held up as sacrosanct either.

Namely that an electronic transformer is not a transformer (especially as it actually contains a small 'genuine' transformer) - it seems perfectly authentic to me.

 

[stillp]

The IEC definition of a transformer is "electric energy converter without moving parts that changes voltages and currents associated with electric energy without change of frequency". There is nothing to say it has to use induction, and nor does it say that it cannot change the waveform. The world has moved on from the days when the only device that could meet that definition consisted of a couple of coils of wire on a ferrous core.
http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=151-13-42

 

[winston1]

The IEC definition of a transformer is "electric energy converter without moving parts that changes voltages and currents associated with electric energy without change of frequency". There is nothing to say it has to use induction, and nor does it say that it cannot change the waveform. The world has moved on from the days when the only device that could meet that definition consisted of a couple of coils of wire on a ferrous core.
http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=151-13-42

By that definition a DC power supply would not be a transformer as the frequency is changed to zero.

Also the PWM switch mode supplies used for halogen lights would not be a transformer either as the frequency is changed to tens of KHz.

So can you tell me what device other than 2 coils on a core would qualify as a transformer in this moved on world?

Here is a suggestion from me: A series resistor.

 

[stillp]

Also the PWM switch mode supplies used for halogen lights would not be a transformer either as the frequency is changed to tens of KHz.

Sometimes.

So can you tell me what device other than 2 coils on a core would qualify as a transformer in this moved on world?

For example, a PWM switch mode supply with a fundamental output frequency equal to its input frequency.

 

[winston1]

Sometimes.

For example, a PWM switch mode supply with a fundamental output frequency equal to its input frequency.

Examples?

 

[stillp]

Examples?

Honeywell electrostatic air filters.

 

[winston1]

Honeywell electrostatic air filters.

Googled that but couldn't see anything relavent.

 

[JohnW2]

For example, a PWM switch mode supply with a fundamental output frequency equal to its input frequency.

Although theoretically possible, I can't say that I have ever come across such an animal, and I'm not sure that I can see what the point might be. As I understand it, the main reason for the high frequency in most PWMs is so that the ('real', inductive) transformer that most of them contain can be physically small. If one were going to "do everything at 50Hz", with all the power going through a transformer (inductive), then I would think one might just as well forget the PWM bits and use just the (relatively large) transformer.

Kind Regards, John

 

[stillp]

Googled that but couldn't see anything relavent.

Well, they can't possibly exist then!

Another example would be soft-starters.