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From: cees@maestro.htsa.aha.nl (Cees Keyer)
Newsgroups: sci.electronics
Subject: Re: Transformer Troubles
Message-ID: <999@maestro.htsa.aha.nl>
Date: 28 Jul 89 09:10:13 GMT
References: <536@winnie.fit.edu> <1496@ns.network.com> <2541@ccnysci.UUCP>
Reply-To: cees@maestro.htsa.aha.nl (Cees Keyer)
Distribution: sci.electronics
Organization: AHA-TMF (Technical Institute), Amsterdam The Netherlands
Lines: 47

In article <2541@ccnysci.UUCP> sukenick@ccnysci.UUCP (SYG) writes:
>>Multiple parallel transformers do work (as long as you get all the
>>polarities correct!)  In fact, internal to many transformers are parallels
>
>Wouldnt you have to find matched transformers (close in real voltage)?
>What if the voltages are slightly different?
>(ie: there may be variations in voltages of 12.6 V transformers)
>Wouldn't one act as a sink and heat up if the voltages arent matched?
>What is a good rule of thumb for the max diff in volts?
>
>Where is Theremagoochymin's rule when you need it?

A rule of tumb is that the secundary voltage of two parallel transformers
must be with in 0.5% equal to each other for small <1 KW trans.

The difference between the power output off the transformers must be within a factor 3
So if 1 trans. is 1 KW the other must be smaller than 3 KW.

Last but not least the factor 
				e = Vshort/Uprimary * 100% 
 
 must be the same. Vshort is the voltage aplied to the primary coil with
 the nominal current flowing trough the primary coil and the secundary coil
 is shortend, like this

	 -------) || (-----------
	Inom >  ) || (		|
		) || ( 		|
		) || (		|
		) || (		|
	--------) || (-----------

So these are the rules for transformers parallel.

The terms I used are poor translations from dutch so don't flame me
about the language used.

#include disclaimer.h 
#include language.h

Cees Keyer.

-- 
DISCLAIMER: I am not insane, I am a plane.
Cees Keyer, Algemene Hogeschool Amsterdam.      
department of electrical engineering.          
UUCP:  {backbones}!tamtam!cees cees@htsa.aha.nl cees@tamtam.htsa.aha.nl