ECN Forum Forums Technical Discussion Electrical Theory and Applications Polarity Test 1

This Schematic shows how to find the relative polarities of Secondary Windings on a 1 phase Split-Coil Secondary Transformer.

For this test, connect a "Test Jumper" between the Secondary Windings so they are connected in Series.
Using a common DVM [Digital Voltage Meter], measure voltage output, as shown and represented by the "E" in the circle.

Any comments???

Scott SET - posted 07/02/01

Scott,
this is probably lame...
can you define 'polarity' ?

Steve,

Not lame at all! I'll try to cover it with a brief explaination:

This polarity is referring to the relationship[s] between the direction of current flow on a primary winding, the induced flow direction in the core, and the direction of induced current flow on a secondary winding - all at one certain instance [such as above the zero line on a sine wave].
This is considered to be Relative Polarity.
It differs from a Fixed Polarity, which is found on typical straight-line DC sources [such as drycells and Batteries], or on Magnetic Stuff [like Permanent Magnets].

Using the Schematic above, what we are trying to find here is which of the leads should be tagged as "X2" and "X3", so the coils can be properly connected in either Series or Parallel.

***Side note*** If the secondary is to be used as the typical "3 wire" system - tapping into the jumper between the split coils for a Neutral Conductor -, but was setup with polarity as shown in "Fig.2", then each of the L-N circuits would be able to function correctly, however the L-L circuit would not function properly.

Kind'a cool, isn't it???

Sure hope this makes some sense!!!

Scott SET

P.S. - Are these Schematics of any help, interest, or benifits to anyone???
Do they need more information or better drawn symbols???
Basically what I am getting at is what everyone thinks of the Schematics, plus any input or suggestions you might have.
If you would like to see a certain schematic posted here, let me know!

SET

[This message has been edited by Scott35 (edited 07-03-2001).]

Scott,

Really, from looking at this a better graphical display would show the leads for s2 (in fig 2) reversed in relation to fig 1. Am I correct?
I just want to know that I am understanding it correctly.

Where would the input (primary) relative polarity symbol be on these diagrams?

I think that you're doing a great job! And I like the term "Relative Polarity"


Bill

>Really, from looking at this a better graphical display would show the leads for s2 (in fig 2) reversed in relation to fig 1.

I took these to be single line drawings - not pictorial views.

I think what you are saying is that pictorial diagrams are more useful --- and I agree with you on that.


>Where would the input (primary) relative polarity symbol be on these diagrams?
If it is a single-line drawing, you may place it at either input to the primary coil.

In the pictorial view, it would make a difference (and should be at the top in figure 1); but I will be very surprised to find that figure 2 is pictorial.

All the relative polarities on the secondaries show is how they are connected, not how they are wound on the core.

Whether they are series-coordinated or series-opposing makes the difference on whether they add or subtract.

>I think that [Scott is] doing a great job!
I do too!


[This message has been edited by Dspark (edited 07-05-2001).]

Bill and Dspark,

Thanks for the reply Q's!!!

1st off, Dspark has pretty much answered the questions better than I can, so I'll avoid confusing things and only add a little bit of information that should have been included with the original schematic post:

These are definitely 1 line schematics. This makes them more like an actual analysis of how things are working, than a graphical representation of the component - such as the typical pictorial symbols.

On the secondary of Fig. 2, the coil s2 is shown on the 1 line to have polarity opposite that of the coil s1.
This is the equivalent to reversing the leads, as Bill was referring to.
So on a pictorial schematic, the coils' leads would be as follows:

<OL TYPE=1>

[*]X1 would be the lead with the polarity mark on coil s1,

[*]X2 would be the other end of coil s1,

[*]X3 would be the lead with the polarity mark on coil s2,

[*]X4 would be the other end of coil s2.
</OL>

This diagram shows the relative polarity at fixed points, which will reflect on the connections' "X" numbers.

In a round about way, this will show how and why a reversed connection to the s2 coil will have an effect.

There's nothing wrong with how you are thinking!!! That's the end result we are trying to achieve with this test!!!

Now as to the polarity to the primary input, if we setup the secondaries as shown in Fig.1, then the relative polarity on the primary will be at the opposite corner of the secondary.
In other words, if the secondary coils have rel. polarity established at the uppermost end[s] of the winding[s], then the rel. polarity on the primary would be on the lowermost end[s] of the winding[s].
Does this make sense???

To obtain pri/sec polarity, check out the schematic "Polarity test 2".

Hope this answered the Q's properly.

Thanks for the nice words, too!!!

Also, great reply from Dspark as to Bill's questions.

Scott SET

Scott,

I'm working on my honorary P.H.D.

Keep 'em coming. Nice Job. Thanks.

***BUMP***

Scott35