Consumption of an electric transformer

[delnoram]

Scalded by the measurements with the PM230 Wattmeter on the external power supplies (for now) of the various low voltage devices connected to the mains.

so I measured the consumption of the 4 types of transformer lying around in my tiny workshop.

Whether "standard", molded or toroidal, the measurements have only confirmed that they are "" gourmet "".

However the last model strongly resembling a type R transformer (said new, yet mine dates from 1989), gave nothing as empty consumption (the PM230 does not measure below ~ 4.6W).

So I connected 2 LED bulbs (2x4.6 = 9.2W) in addition to the 9.2W transformer

I put a load of 3.3W on the secondary of the transformer:
the total varying from 11.4 to 13.8W (including LED spots) which gives us 2.2 to 4.6w for the transformer and its load, i.e. a consumption of -1.1 to 1.3w for the transformer alone
(a negative consumption , here I am lost ).

The transformer + its load without spots 6.9w.
The transformer + its load + a normal bulb (38.59W) = 43.13
The transformer + its load + a fluorescent bulb (9.54W) = 13.4W.

In short an interesting phenomenon, not very understandable.

If someone has an idea........

[elephant]

I think that a wattmeter is not the ideal device for making measurements of such low consumption: it is a particularly economical model.

I would rather make these measurements with an ammeter and a voltmeter

[Other]

Hello,
this is the first time I hear that a transformer is greedy!
A large transformer well designed with good oriented crystal sheet and a well calculated winding has an efficiency in the 95% and more, are efficiency is better in load if the winding is well calculated, connect to the right tapes and the right frequency. When empty it is not so good,
The magnetic losses according to its 3-branched core design as well as the heat generated by the induction plates are losses, as great when empty as when loaded. In load it is the losses due to the size of the wire of the windings.
Still pay attention to what we measure, watts or volt amps.
A welding machine because of the particular case of this transformer has a fairly high reactive consumption when empty
the design of this transformer and wanted to have a higher no-load voltage and a certain magnetic leak wanted when asked for amperage, Its primary winding has more turns than a normal tranfo.

Andre

[Christophe]

Very good initiative that I can only encourage!

I do not know much about it (mechanic requires) and am therefore delighted by this subject!

Note for André: I think Delnoma has measured AC-DC and non-AC-AC transformers, hence the high consumption ...

1) I measured the consumption of my router myself with the PM230 (see https://www.econologie.com/forums/campagne-d ... t2115.html ) I quote :

1) ADSL Modem-Router: 20,7 W when you unplug the router and just leave your tranfo you find: 18,4 W Shocked
The router itself consumes only 2,3 W but its tranfo consumes 18,4! The system yield is therefore miserable, 11,1%! Evil or Very Mad It is a safe bet that all small transformers have similar performance ... hence their heating!

It is obviously an AC to DC transformer (230V to 12V-1A)

2) It is widely accepted that AC-AC tranfo have a yield of around 95% (André's value which I find high, I would rather say 90%). To know (at least) the line losses of the EdF network (for example) it suffices to set 0.9 to the power of the number of transformers.

If we have 4 current transomation (fairly low but realistic value starting from 50 V alternator going up to 000 for transport, then going down to 400, 000, and finally 63 or 000) we already obtain losses 20 ^ 000 or 380 or ... 220% of losses on the processing line! Not to mention obviously the linear losses in the cables themselves (I don't know how to estimate them).

All those who claim (me a while ago) that the online losses of EdF are therefore less than 10% are therefore wrong ... or when they prove to us the opposite ....

[Christophe]

If someone has an idea...

Well you should already tell us what type of transformer it is ... AC-DC I guess ok but what output voltage?

To make precise measurements you would have to measure:

1) 230 V input with PM230

2) Output with Ampere + Voltmeter.

We don't know at all how you measured the exit ...

[delnoram]

I think that a wattmeter is not the ideal device for making measurements of such low consumption: it is a particularly economical model.

I would rather make these measurements with an ammeter and a voltmeter

If you want, I can give you these measurements: Measured
"standard" tranfo 220Vac 160VA - 24Vac 2A.
vacuum 229.5Vac x 119.7mA

Type R transformer (sorry it is Chinese) 220vVac ~ 30VA? 10vAC-24Vac outputs
no load 228.5 x 2.75mA

[delnoram]

Hello,
this is the first time I hear that a transformer is greedy!
A large transformer well designed with good oriented crystal sheet and a well calculated winding has an efficiency in the 95% and more, are efficiency is better in load if the winding is well calculated, connect to the right tapes and the right frequency. When empty it is not so good,
The magnetic losses according to its 3-branched core design as well as the heat generated by the induction plates are losses, as great when empty as when loaded. In load it is the losses due to the size of the wire of the windings.
Still pay attention to what we measure, watts or volt amps.
A welding machine because of the particular case of this transformer has a fairly high reactive consumption when empty
the design of this transformer and wanted to have a higher no-load voltage and a certain magnetic leak wanted when asked for amperage, Its primary winding has more turns than a normal tranfo.

Andre

hi Andrew
Gourmand is between Quotes, it begs the question
the watcher gives us what to measure:
Power Active or Active + Reactive?

[Christophe]

vacuum 229.5Vac x 119.7mA

It means: 27 W empty for 1 AC-AC transformer if I'm fine?

Type R transformer (sorry it is Chinese) 220vVac ~ 30VA? 10vAC-24Vac vacuum outputs 228.5 x 2.75mA

In this case 0,63W for a type R ... uh question: what does type R mean?

[Christophe]

hi Andrew
Gourmand is between Quotes, it begs the question
the watcher gives us what to measure:
Power Active or Active + Reactive?

No wattmetre can measure (well give reactive power I think ...

It therefore gives the active power = A * V * Cos (phi) in W
Reactive power = A * V * Sin (phi) in VA if I remember correctly ... so finally it would be easy for 1 wattmetre to give it (by calculation)

[delnoram]

If someone has an idea...

I do not know much about it (mechanic requires) and am therefore delighted by this subject!

Note for André: I think Delnoma has measured AC-DC and non-AC-AC transformers, hence the high consumption ...

Well you should already tell us what type of transformer it is ... AC-DC I guess ok but what output voltage?

To make precise measurements you would have to measure:

1) 230 V input with PM230

2) Output with Ampere + Voltmeter.

We don't know at all how you measured the exit ...

Neither do I know much about it, I am only a self-taught in electronics, computing, electricity I just adjusted some bases dating from school (about thirty years ).

Not Ac Dc, but only the transformer (for empty measurement).
In charge
I always measure the output with 1 ammeter and 1 voltmeter placed after the ammeter to take into account the drop in voltage generated by it.

The load is 1 bridge rectifier and 1 PC fan.

For the record, my first measurement in charge with the PM230 I made it on 2 12Vac led spots in series on the 24Vac output.
To avoid zero (consumption of minus 4.6w) I therefore put 2 LED spots including the given consumption and always 9.2w (minimal variations due to fluctuations in the sector).
the result of the 2spots 220Vac + transformer + 2spots 12vac in series ........ 9.2w.
With 4 12Vac spots (2x2) 11.7w result.
here you have everything