Use of the word "transformer"

[JohnW2]

Perhaps, but what does it transform?

An earth (or whatever)-referenced supply to one that is not earth (or whatever)-referenced.

Kind Regards, John

 

[JohnW2]

For what it's worth, IEC 61558 "SAFETY OF POWER TRANSFORMERS, POWER SUPPLIES, REACTORS AND SIMILAR PRODUCTS" contains the following: NOTE 1 The distinction between transformers, power supplies and switch mode power supplies is as follows: ....

Are they therefore saying or impyling that power supplies and switch mode power supplies are different from (hence 'not') transformers?

Kind Regards, John

 

[stillp]

A pair of cutters would do that. Does that make a pair of cutters a transformer?

Edit: refers to post #76

 

[stillp]

Are they therefore saying or impyling that power supplies and switch mode power suppliers are different from (hence 'not') transformers?

Yes, that was my point.

 

[JohnW2]

A pair of cutters would do that. Does that make a pair of cutters a transformer?

I can but presume that's what EFLI would say! He appears to be insisting that anything which 'can transform' is a transformer.

As I said, plants, livers and goodness-knows-what also qualify as transformers by that definition!

Kind Regards, John

 

[JohnW2]

Yes, that was my point.

That's what I thought was your point. Do you agree with it? If so, then welcome to the club

Kind Regards, John

 

[stillp]

That's what I thought was your point. Do you agree with it?

In the context we're discussing, that of "black boxes" that are used convert 230V mains supplies to 12V for the purpose of powering luminaires, I don't think the distinction made in 61558 is relevant, since the frequency of the output has no significant effect on the function. However, bear in mind that 61558 is a safety standard, and the test needed to prove a PSU is safe will be very different from those needed to prove a wound transformer is safe. I can only suppose that is why the distinction is made.

 

[bernardgreen]

Not forgetting that almost all switch mode power supplies create and in many cases radiate radio frequency energy. A wound transformer does not create radio frequency energy.

 

[JohnW2]

In the context we're discussing, that of "black boxes" that are used convert 230V mains supplies to 12V for the purpose of powering luminaires, I don't think the distinction made in 61558 is relevant, since the frequency of the output has no significant effect on the function.

I think the context of the discussion has actually been a lot wider than that, since some involved would seemingly want to justify calling an SMPSU a 'transformer', regardless of its size or the nature of the load. Furthermore, some of the participants in these discussions have suggested that some 'light-producing loads' (I want to avoid that discussion ) might not be happy with high-frequency AC.

However, bear in mind that 61558 is a safety standard, and the test needed to prove a PSU is safe will be very different from those needed to prove a wound transformer is safe. I can only suppose that is why the distinction is made.

That's true. However, in that context, the primary distinction seems to be whether or not the output frequency differs from the input frequency, without any mention of whether or not the device is, or includes, a wire-wound 'whatever' (!) - and that (the frequency change) would seem to me to be fairly irrelevant to the type of safety testing required.

Kind Regards, John

 

[stillp]

However, in that context, the primary distinction seems to be whether or not the output frequency differs from the input frequency, without any mention of whether or not the device is, or includes, a wire-wound 'whatever' (!) - and that (the frequency change) would seem to me to be fairly irrelevant to the type of safety testing required.

But an assembly of electronic components will have many possible failure modes, that are different from those of a wound transformer, hence the test to reveal those failures will be different.

 

[JohnW2]

But an assembly of electronic components will have many possible failure modes, that are different from those of a wound transformer, hence the test to reveal those failures will be different.

That was my point. As you say, the failure mode of those two would be very different, requiring different safety tests - but 61558 does not seem to make a distinction on the basis of whether it is primarily 'electronics' or wire-wound - only by frequency (and waveform) changes. Admittedly, a wire-wound transformer will not change frequency (although may introduce some harmonics), although it may change (distort) waveform - but, the other way around, one could certainly create (soemthing that you and I would call) a 'power supply' that did not significantly alter either frequency or waveform -in which case I'm not sure what 61558 would regard it as.

Kind Regards, John

 

[stillp]

I'm not sure what 61558 would regard it as.

It (61558) wouldn't regard it at all, since it would be outside the scope.

 

[JohnW2]

It (61558) wouldn't regard it at all, since it would be outside the scope.

If something such as I described (which surely would qualify as a "power supply") is not within the scope of a Standard entitled "SAFETY OF POWER TRANSFORMERS, POWER SUPPLIES, REACTORS AND SIMILAR PRODUCTS", what would it be within the scope of? (or, for EFLI, "... within the scope of what would it be?")

Kind Regards, John

 

[stillp]

No idea without some research. The point is that the standard covers power supplies that change the frequency, so for the ones that don't, you'll have to find a different standard, or use generic standards.

 

[JohnW2]

No idea without some research. The point is that the standard covers power supplies that change the frequency, so for the ones that don't, you'll have to find a different standard, or use generic standards.

Fair enough. However, I would have thought that a power supply such as I described would require the same safety tests as one which did change the frequency, wouldn't it? After all, it would seem that a power supply which changed the frequency from, say, 50Hz to 50.1 Hz, or from 50Hz to 49.9 Hz (and effected some equally trivial change to waveform) would be within the scope of 61558.

Kind Regards, John