Delta and Star Xformer Connections

To: tesla-at-pupman-dot-com
Subject: Delta and Star Xformer Connections
From: Mike McCarty <mmccarty-at-dnaco-dot-net>
Date: Sat, 14 Sep 1996 13:05:19 EST
> From: huffman <huffman-at-fnal.gov> 
> To: tesla-at-pupman-dot-com 
> Subject: Re: More Tuning/Debugging 
 
>snip 
> > > 2) Since I have already have an investment in the 25KVA pig which 
> > > is rewired on the low voltage side so that both 120 volt windings 
> > > are in parallel ("Star")... If I plunk for another 7200-120/240 
> > > pig, would it be better to rewire the second pig to match the 
> > > first, and run the two "Star" wired LV windings in series to get 
> > > to 240 volts input... Or, should I rewire my existing pig so that 
> > > Richard Quick 
> > >  
> > > ... If all else fails... Throw another megavolt across it! 
> > > ___ Blue Wave/QWK v2.12 
> >  
> > Richard, 
> > 	If I were you I'd buy a second 7200-240/120 pig. That way 
> > your original investment is'nt wasted. Unless of course you 
> > can trade your old pig in. Second, I'd rewirer your LV back to the 
> > Delta configuration and wire the pigs together for parrelel 
> > operation (While your HV are in series). This is my opinion, 
> > I like keeping things simple. 
> >  
> > 	Last, who do you know that sells 14,400 10 KVA pigs? 
> > 	I'd like to have thier phone number. 
 
> What is this 'star' 'delta' stuff anyway? I thought these pigs were single 
> phase? I am familiar with these terms in a three phase system however. I 
> also realize that the  120/240 side is two phase 180 deg. ( my roommates 
> and I once got 240 by using two separate wall sockets in our appartment). 
> dave huffman 
 
When setting up these transformers for use in a three phase bank the secondary   
windings are wired in series for a delta service and in parallel for a wye (or   
"star") service.  Yes, he is using a single transformer for single phase power but   
is using the star and delta references to explain how the the secondary coils are   
connected.  These references can be confusing at times.  To me it's easier to say   
"they are in parallel or series"  than to say "they are in a delta or wye   
configuration" when making references to a single phase setup. 
 
By the way, the 240 volt power you speak of in a residential setup isn't "two   
phase".  It's still single phase power, you just have two ungrounded conductors   
instead of the one grounded, one ungrounded conductors that you have with 120 volt   
power. 
 
-Mike McCarty