Transformer wiring question

Thread Starter

stujohns

Joined May 1, 2021
6
I hope this is allowed to be posted here.
I have a whole case of these transformers with no wiring instructions.
I can't find any info online with the maker or part number.
Being US made I'm going to assume it is a 120VAC primary but who knows?
I am unsure how to hook it up and see what the output measures.
Anybody have a suggestion about wiring this unit?
Thanks in advance
Stu. DSCF1331.JPG
 
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crutschow

Joined Mar 14, 2008
27,756
You can try hooking the transformer up to 120Vac using a small 120V incandescent bulb (e.g. 5-25W) in series to limit the current in case the primary is not rated for 120V.
If connected properly the bulb will be dim or not lit.
The you can check the secondary (presumably the colored wires) for the voltage outputs.

You can use an ohmmeter when power is not applied to determine which wires are connected.

In your picture the primary is likely the black and white wires.
The reason for three wires may be the transformer is for 120V or 240V depending on which two you use.
 

Thread Starter

stujohns

Joined May 1, 2021
6
Awesome!!! I never thought about the light bulb in case of a bad guess on applying primary.
Thanks much! I'm on it!
Stu
 

dl324

Joined Mar 30, 2015
13,142
Welcome to AAC!
Being US made I'm going to assume it is a 120VAC primary but who knows?
It wouldn't be unusual for US manufacturers to make transformers intended to operate from 240VAC. Just as it wouldn't be unusual for equipment manufacturers to make devices that can operate from 120VAC or 240VAC.
 

Ian0

Joined Aug 7, 2020
3,280
Yes. That's the stuff. I've heard it said on the telephone but never seen it written down.
My transformer supplier made an inductor unvarnished, and send some with it so I could dismantle it to adjust the inductance.

The point is that if it's an inductor not a transformer, all the E's and I's will be stacked the same way up and you will be able to see the presspahn that makes the gap.
 

MaxHeadRoom

Joined Jul 18, 2013
23,642
Presspahn is the name of the company, that's vulcanized fibre (fish paper).
It was commonly known as Presspahn when i did a stint motor winding, it was developed around 1924, and has been the popular choice ever since.
Everyone I knew in the industry called it by Presspahn.
 

Ian0

Joined Aug 7, 2020
3,280
The product probably says "Presspahn" on it, so that's what people called it!
Even the company website acknowledges that the product is called "presspahn".
 

MaxHeadRoom

Joined Jul 18, 2013
23,642
When I went through my training in UK it was extensively know as a product descriptor, most likey as it was developed in the UK.
These seem to prove the point.
Oxford English Dictionary:
Origin

Meaning of presspahn in English:
Early 20th century. From German Preßspahn, variant of Preßspan (now Press-Span) pressboard (originally pieces of card for pressing clothes) from press-, combining form of pressen to press hard, compress + Span shaving, chip, splinter from the same Germanic base as spoon

Current ad example.
 

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Thread Starter

stujohns

Joined May 1, 2021
6
Ok, who is the transformer expert here. It is not me.
I have a case of these. I was unable to really determine anything useful in playing around with regular 120VAC current.
I'm happy to mail one of these NEW to a select expert free of charge who is willing to tell me the primary and secondary and wiring on this rascal.
Any takers or nominations?
I did email the OEM but have not heard anything back.
Thanks!
Stu
 

Thread Starter

stujohns

Joined May 1, 2021
6
I recorded no output voltage from any combination of the red and yellow wires when supplying 120VAC via the lightbulb safety method input thru any combination of the black, blk white stripe or white wires. I am not even sure these are the inputs???
I direct wired 120VAC into the black and white and dimmed the shop lights and created a lovely buzzing sound.
Just seemed safer to cease the experimenting on my own.
 
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