Can't See Images? Troubleshoot Here!

[phyq]

Hi, is the correct picture this one:


or:

Not sure why can't you see them. When I open this post incognito mode i can see them.

first one:
https:// imgur.com/p6YSBOs
second one:
https:// imgur.com/a/UhAmJKF

(remove space before i to open them)

 

[Borek]

Please attach your images to your post, at the moment they are not displayed to everyone.

 

[berkeman]

I can see both images now, and they look the same. Are they supposed to be different? Are you asking about the dot convention for the input and output voltage polarities? If so, you are not showing any dots on the windings so far...

https://www.electronics-tutorials.ws/wp-content/uploads/2018/05/transformer-trans63.gif

https://www.electronics-tutorials.ws/wp-content/uploads/2018/05/transformer-trans63.gif

EDIT -- @Merlin3189 noticed that the bottom secondary winding has an inverted sine wave when it should not. Because of the labeled polarity of the Va and Vb outputs, both of those waveforms will be in phase. The equations are correct to the right of the drawing, but the phase of the bottom secondary waveform should not be inverted. Further discussion here:

https://www.physicsforums.com/threa...center-tapped-transformer.982403/post-6295679

 

[DaveE]

Is this one of those puzzles where you're supposed to find the difference in the pictures? I seem to have failed.
Your links don't work.
Well formed questions get better answers. Perhaps you should try again with a little more detail?

 

[phyq]

I'm not sure what happened with the pictures
I must have change the second one when I was editing the post. :/
The pictures are:



I'm asking what is the correct way to represent sine of the output voltages (on a same plot) for a center-tapped transformer.

 

[Tom.G]

I'm asking what is the correct way to represent sine of the output voltages (on a same plot) for a center-tapped transformer.

Image 53, the top one in your post #5, is correct.
The voltage on each part of the secondary winding is centered around Zero.

Another way of saying it is that they change polarity just as the primary does. (This is true for a Sine wave and some other common conditions. There are some special cases (they get kinda involved) where this is approximately, not strictly, true.)

Cheers,
Tom

 

[Baluncore]

I'm asking what is the correct way to represent sine of the output voltages (on a same plot) for a center-tapped transformer.

 

[Merlin3189]

https://www.electronics-tutorials.ws/wp-content/uploads/2018/05/transformer-trans63.gif

I was just looking at this to try to steal a picture to answer another thread, but it looks wrong.
The sin graphs shown on the two secondaries should be in phase.
Apart from being obvious, the maths on the right says so.
$\frac {N_A}{N_P} and \frac {N_B}{N_P}$ are numerical constants. So when multiplying the vector $V_P$ only the amplitude is changed, not the phase. So both must be in phase with $V_P$

Although $V_A$ and $V_B$ are marked with double headed arrows, suggesting phase is irrelevant, the + and - marks do indicate the oscilloscope should be connected a certain way round. The currents are also indicated in one direction, presumably that of positive phase.

I note in Baluncore's oscillogram, the centre tap is shown as ground, so that the opposing phases are appropriate there.

 

[berkeman]

I was just looking at this to try to steal a picture to answer another thread, but it looks wrong.
The sin graphs shown on the two secondaries should be in phase.

Yes, I agree now that I look at it again. The way they have the +/- secondary terminals labeled, they have to be in phase. When you flip the +/- terminal definitions of the bottom winding (like for the full-wave rectifier example), that's when you get the inverted waveform.

Good catch! I'll deprecate that other post when I get a chance. Thanks.

 

[Windadct]

Personally - when this type discussion comes up I prefer to use the terms Van and Vbn, this emphasizes the reference to the neutral ( center tap).

Also valuable in 3Ph to list Vab, Vbc and Vca