tranformer diagram

[Joe G]

what are the "black dots" on data sheet diagrams adjacant to 2 of the four pins. I have a Triad VSPP28-2000 transformer and on the diagram, by two of the four pins there is a black dot? i've been trying to find out what they mean, if anything? thanks, I'm just getting back into a hobbie that stopped 20 years ago and picking up where i left off?

 

[kchriste]

The dots indicate which ends of the windings are in phase. They help when you are trying to put windings in series or parallel.

 

[Joe G]

thank you. so they do matter.

 

[colin55]

I think it's a little bit more complex than that.
I have always taken it as the start of each winding - making sure all the windings are wound in the same direction.
If you have a primary winding and mark the start with a dot, and have a secondary winding and mark the start with a dot, what is the phase relationship??
The dots are sometimes necessary to help with a third winding (feedback) to produce oscillation etc.

 

[mbarazeen]

dot convention

if you put an arrow to show the direction of current in the primary winding, and if the head of the arrow is near the dot (ie towords the dot and entering the transformer) then the induced voltage by that current would be having the direction on other windings as denoted by arrows (head- high side) se the attached pic

 

[colin55]

The dots indicate which ends of the windings are in phase.

This means the dots on the primary and secondary are not in phase.

 

[BrownOut]

This means the dots on the primary and secondary are not in phase.

No, they ARE in phase.