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-   -   Isolation Transformers/ Auto-Transformers (https://www.electriciantalk.com/f2/isolation-transformers-auto-transformers-187689/)

DerekS 12-19-2016 11:41 AM

Isolation Transformers/ Auto-Transformers
 
Hey everybody, I had an interesting discussion about transformers over the weekend. Particularly the difference between Auto-Transformers and Isolation Transformers. I realize Isolation Transformers have no electrical connection between the primary and secondary windings, and are also bigger in size, but what other characteristics make it easy to identify an isolation transformer over an auto-transformer.

PlugsAndLights 12-19-2016 01:10 PM

I'd look at the diagram on the nameplate first. Other info on the nameplate
would also give it away.
Wondering if I missed the point of the question.............
P&L

telsa 12-19-2016 01:37 PM

The connection diagram ?:)

brian john 12-19-2016 03:17 PM

Most to Autotransformers are isolation transformers, just the connection is such that the secondary is connected to the primary and is used to boost (increaser) or buck (decrease) voltage typically in small steps. 120 to 24 isolation can be buck or boost depending as noted on the connections made in the field.



Boosting or bucking from 120 to 277 or 208 to 480 would require additional steel and copper or aluminum and therefore is not practical, as there is little to know cost savings,

Cl906um 12-19-2016 04:46 PM

Isolation transformer for surgery that monitor loss to ground or any loss for that matter?

dmxtothemax 12-19-2016 07:23 PM

with an ohm meter you test for any continuity between promary and secondary windings, with isolation there should be none, but with auto-trasfomer there will be.
in other words auto = no isolation.

brian john 12-19-2016 10:26 PM

Quote:

Originally Posted by Cl906um (Post 3477849)
Isolation transformer for surgery that monitor loss to ground or any loss for that matter?

While you are correct the question is broader than just an ungrounded isolation transformer used in operating rooms.

brian john 12-19-2016 10:27 PM

Quote:

Originally Posted by dmxtothemax (Post 3478201)
with an ohm meter you test for any continuity between promary and secondary windings, with isolation there should be none, but with auto-trasfomer there will be.
in other words auto = no isolation.

Yes but I can take an isolation and make it a Auto transformer. .

Cl906um 12-20-2016 06:00 PM

Quote:

Originally Posted by brian john (Post 3478777)
While you are correct the question is broader than just an ungrounded isolation transformer used in operating rooms.

Was just wondering where his question was derived from. Kinda wondering why so vague.just thought I would put out one of its benefits used in the field.

Frank Mc 12-21-2016 04:31 AM

Not sure if i got this right , but i recall that an isolation transformer has a physical mechanical barrier between primary and secondary...??

Frank

inetdog 12-21-2016 03:37 PM

Quote:

Originally Posted by Frank Mc (Post 3481561)
Not sure if i got this right , but i recall that an isolation transformer has a physical mechanical barrier between primary and secondary...??

Frank

That would be a "high isolation" transformer. Typically including a grounded electrostatic shield between the windings. Minimizes capacitive coupling between windings but does nothing do anything for magnetic coupling (Duh!)
To get rid of differential mode noise you would have to add tuned filtering.

Sent from my XT1585 using Tapatalk


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