[AMPS] Re: Two XFMRs Parallel...

[J. Bradshaw]

OK, so that being the case, there would be no need to isolate them 
at all if the output voltages were fairly close.  The only thing to worry 
about would be that the lower voltage transformer would become 
part of the load.

Actually I thought that switching grids would be a bit of a nightmare.  
I have seen this done at the generator end, and some attention to 
detail is required to prevent one of them from becoming the motor.

Jim
----- Original Message ----- 
From: "Tom Rauch" <w8ji@contesting.com>
To: "David Kirkby" <drkirkby@ntlworld.com>; "J. Bradshaw" <ac6tk@cybertime.net>
Cc: <amps@contesting.com>
Sent: Friday, January 19, 2001 12:00
Subject: Re: [AMPS] Re: Two XFMRs Parallel...



Hi Jim,

> Ok, I thought the phase (with respect to the primary) could be varied
> by the lead dress off the secondary, and how they come off the core.
> That is, the position of the exit with respect to the alignment of the
> field at any given instant.  

No, that would only control the amplitude.

The flux lines would cut that area at a different angle, and that 
would produce a different voltage, but not a different phase.

The exception is when the wire parallels the flux lines. Moving past 
that point can suddenly flip phase 180 degrees.


If two transformers have different
> winding exits, won't they have different phases with respect to the
> input and each other?  

No. They do not.

Or is the output phase completely dependent on
> the primary phase?

Yes it is. The only exception is if the transformer has so much flux 
leakage that the current is limited or controlled by transformer 
reactance. That would be a poor transformer.

We could simulate that by placing a capacitor or inductor in series 
with the winding. In that case, phase would b depend on load 
impedance and reactance. 

  My suspicion is that the output may be something
> besides 0 and 180.  Heck this is easy to test with a dual-trace scope
> on both Xfmrs (with appropriate resistive voltage dividers).

Sometimes it helps to look at other systems. If it did happen, 
imagine the nightmare utility companies would have in connecting 
power grids! 

If you can come up with a way to make a simple transformer fed 
from a single phase source be able to rotate phase without adding 
ESR or reactance to the system or being large in terms of the 
wavelength, patent it! You will quickly become a millionaire.

 
73, Tom W8JI
w8ji@contesting.com

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