Two Xfrmrs, Quadplex, What's This?

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  #1  
Old 04-09-11, 06:38 PM
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Two Xfrmrs, Quadplex, What's This?

I had recently seen a couple of services where there are two xfrmrs connected to two seperate phases, and then connected to the building using quadplex. One of the service conductors usually has red heatshrink. What is this and how does it work? Thanks for all of the help and patience, guys!
 
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Old 04-09-11, 07:10 PM
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re-read your post,you said 2-wire primary.maybe just two services.other wise not sure.or 2 phase.
 

Last edited by oleguy; 04-09-11 at 07:45 PM.
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Old 04-09-11, 08:45 PM
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Are you sure it isn't three phase primary? Open delta supplying 240 three-phase and 240/120 single-phase will often use two transformers if the three-phase load is significantly smaller than the single-phase load. Usually there will be a larger transformer for the siingle-phase load.

 
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Old 04-09-11, 09:16 PM
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There are few spots that have open wye - open delta system as well it is common with some of the resdentanal area and commercal with limited triphase loads { typically a/c units or compressour motour }

Merci,
Marc
 
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Old 04-10-11, 05:11 AM
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The one I saw yesterday was only connected between phase A and B, phase C was nowhere to be found for at least a mile, if not more.
 
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Old 04-10-11, 09:59 AM
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Are you saying that the two individual transformers each had their primary connections to ONLY the two visible phase conductors? Essentially two transformers paralleled on the primary but separate on the secondaries and only two conductors on each transformer secondary with no interconnection between the two transformers on the secondaries? Any shared connections with the messenger or connections of the messenger to any of the building's service entrance wiring?

Posting a few CLEAR pictures may help.
 
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Old 04-11-11, 09:55 AM
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It's probably an open delta configuration, a.k.a. cheap three phase out in the boonies. You have to derate the transformers to about 50% though so it should only be used when the three phase loads are not too big.
 
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Old 04-11-11, 05:17 PM
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Originally Posted by ibpooks View Post
It's probably an open delta configuration, a.k.a. cheap three phase out in the boonies. You have to derate the transformers to about 50% though so it should only be used when the three phase loads are not too big.
Actually, becoming more popular with lift stations around here. Even the smaller 25kva transformers are more than required.
 
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Old 04-11-11, 05:30 PM
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Here are some of the places that I saw these odd services:
2 gas stations, third phase at the pole
Daycare :scratchhead: ,third phase also at the pole
Abandoned train station, third phase 100'away
Agway, third phase at pole
Resturaunt, third phase 1+ mile away

I'll try to get pics sometime.
 
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