Posted By: Scott35
Polarity Test 3 - 07/02/01 07:12 AM
This Schematic demonstrates how to find relative polarities of two individual and separate 1 phase 2 wire transformers.
The series connection between the Secondary Windings is a "Test Jumper", which is used only during the test procedures.
Test equipment consists of a common DVM [Digital Voltage Meter] - which is represented by the "E" in the circle.
**NOTE** Both Transformers need to be identical for Pri/Sec voltage, KVA and Z.
Scott SET - posted 07/02/01
Posted By: Anonymous
Re: Polarity Test 3 - 07/03/01 07:54 PM
This is a great pair of diagrams!
It shows how when voltages are of the same polarity, they subtract; but of opposite polarity, they add.
Posted By: Scott35
Re: Polarity Test 3 - 07/07/01 09:02 PM
Thanks for the reply!!! Glad the schematics are of use to the members of this forum.
As you said, the schematic demonstrates how relative polarity can either add voltages ["in phase" connections], or subtract voltages ["out of phase" connections].
It's all according to the direction of current flow on the secondary coil[s] - Vs - the magnetic flow in the core.
These polarity test schematics are really aimed more at the "How-To" or the "FYI" angle of things, rather than at anything that is trade applicable [except that anyone performing "in the field transformer connections" would benifit from this info.].
This particular schematic would be helpful if someone was planning to connect two separate transformers for a common output [Parallel Primary connections, Parallel, Series, or even "Multiwire" Secondary connections].
Transformers need to be exactly the same - even as much as being "Cloned" from the other - in order to function properly.
This meaning that not just the input/output voltage being the same, but the core material, winding density, KVA, %Z, reflected Z and all that jazz. Otherwise one winding will circulate a large level of current.
*** NOTE ***
The NEC does not allow the permanent usage of Paralleled Transformers!!! I can understand the reason[s] why!!!
so much for the disclaimer!
Once again, thank you!!! Glad these schematics are of interest.
P.S. Do you have any drawings, or similar tech. data that you could post here???
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