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#70800 - 10/13/06 12:22 PM Isolation Transformers  
polarice66  Offline
Junior Member
Joined: Oct 2006
Posts: 4
Good Day,
I have a question regarding an Isolation Transformer where I work
It is a GE type QL-TE
Model # 9T23C3035
75 kva
3 phase 208 Volt
The windings have a lead (14AWG)coming out of each one, Does anyone know what these leads are for? Any help would be appreciated

Thanks,
polarice


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#70801 - 10/13/06 03:34 PM Re: Isolation Transformers  
Dnkldorf  Offline
Member
Joined: Dec 2004
Posts: 1,064
nowhere usa
The shield between each winding?


#70802 - 10/13/06 03:48 PM Re: Isolation Transformers  
earlydean  Offline
Member
Joined: Dec 2003
Posts: 751
Griswold, CT, USA
voltage taps? Are there lugs as well?
There should be an instruction booklet that comes with it.


Earl

#70803 - 10/13/06 05:20 PM Re: Isolation Transformers  
polarice66  Offline
Junior Member
Joined: Oct 2006
Posts: 4
I was thinking along the lines of the ground shield,but coming from the factory shouldn't they be already connected? They may have been removed prior to when I started working here but why? As for taps, There are several taps comoing out of the front of the wondings. It is an older transformer and there are no shop drawings on site and I couldn't find anything on the GE website


#70804 - 10/13/06 05:58 PM Re: Isolation Transformers  
Dnkldorf  Offline
Member
Joined: Dec 2004
Posts: 1,064
nowhere usa
If this is a 480X208, and someone backfed the thing to get 480 out, and corner grounded it at the transformer, they would of had to removed the shield wires to do this.

I did a search on that model number and came up empty.

Do the tap positions have any wires connected to them?


#70805 - 10/13/06 06:03 PM Re: Isolation Transformers  
polarice66  Offline
Junior Member
Joined: Oct 2006
Posts: 4
strictly isolation, the secondary windings are tapped at 210 volts. there are no wires on the taps other tahn the secodary leads


#70806 - 10/13/06 08:19 PM Re: Isolation Transformers  
Dnkldorf  Offline
Member
Joined: Dec 2004
Posts: 1,064
nowhere usa
post a pic?


#70807 - 10/16/06 01:17 AM Re: Isolation Transformers  
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
Sounds very much to be Shield Leads.

All White Insulation, possibly Tinned stranded conductors?
Should have some tagging either imprinted to the Insulation, or as a label tag - but not always.

Transformer's nameplate may indicate these shield leads on the schematic. The shield would be a dotted line between the coil and the core, and the lead would tap off one side (typically the right side), and run out to a termiantion number.

Not sure why they are not terminated - maybe because there are a couple methods of termination, or possibly some liability issues (???).

Here are some images of Transformer Core/Coil assemblies with Shields:

[Linked Image]

Image #1: 3 Phase 4 Wire Transformer with Shield Leads.
**Note the small white conductors running from each winding at the top (between the coil and the core).
They all collect around the middle, and run upwards on the core.
--------------------------------------------------------------

[Linked Image]

Image #2: Core-Coil view of Spec. Transformer with Shielded Windings.
It's kind of hard to see, but there are small shield leads running out of each winding area.
--------------------------------------------------------------

[Linked Image]

Image #3: Shield Leads Terminations Diagram.
This is from the Transformer above (Image #2), and describes the terminations of shield leads.
--------------------------------------------------------------

[Linked Image]

Image #4: Coil and Shield Leads Schematic.
This is also from the Transformer above (Image #2).
Note the Core is bonded to Ground, and for each winding section, there is Tap info, Lead info, and Shield info.
--------------------------------------------------------------

[Linked Image]

Image #5: Core/Coil view of another Spec. Transformer.
*** Note the Terminal Blocks where the shield leads terminate.

Contact General Electric, and ask them about the terminations of the shield leads, and what to bond them to.
They might refer you to an on-line document, or answer your question directly - or a little of both!
If they reference an on-line document, let us know where the document is at (paste the link in your reply).

Nevertheless, let us know what the outcome is!

Good luck!

Scott35


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

#70808 - 10/17/06 12:18 PM Re: Isolation Transformers  
polarice66  Offline
Junior Member
Joined: Oct 2006
Posts: 4
thanks for the pics and offers of answers, The transformer looks nothing like the ones in the pics, I'll try and provide a few pics within the next day or so,


#70809 - 10/18/06 11:19 AM Re: Isolation Transformers  
SteveFehr  Offline
Member
Joined: Mar 2005
Posts: 1,213
Chesapeake, VA
Built-in current transformers, perhaps? K-factor shields seems more likely, though. Do you know if that transformer has a rated K-factor on it?

As it's a TE, it may also be integrated thermocouples so you can hook up an overtemperature alarm.

[This message has been edited by SteveFehr (edited 10-18-2006).]



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