Electronics > Power/Renewable Energy/EV's

do you know this inductance with three wires

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iso14000:
Hi folks

I have , from a former teardown, this inductance in a drawer.
I decided to measure it .
with L/C ringing after a voltage ramp up I found a quite large inductance : 4 Henry, for ESR of 4 ohms between two wires
the third wire seems almost shorted one the two that exhibit an inductance behavior

This (large) inductance comes from a UPS that gived up, and I was surprised to find it , thinking of chopper filter

the question is : do you have an idea about the third wire?

TimNJ:
Depending on the topology it was used in: Some sort of tapped inductor? Do you measure any inductance between the third wire and some other wire?

4H seems pretty large though! Feel like I'm off.

For example:

Andy Watson:
Probably a custom part made to order. Looks like rasmi are still in business:
https://rasmi.com/
Does the type number align with any of their current products?

Magnetic amplifier ? Auto-transformer ?

iso14000:
Hi

thanks both of you.
at the beginning I didn't believed my RLC meter (a creepy one) , so I used the good old method to make ringing the L by a known C, and I found the L=4H.....
yes  :o like you.

after reading your comments, I did some extra investigation, and Yes it looks like a tapped inductor.
I found a transformer effect by a 1:5 ratio

I'm puzzled about the utility for such a thing...

If i remember well, that UPS used 2x12V lead acid , so I guess by this ratio , a chopper could give 24*5=120V
.... but here in europe we are set with 230Vrms....

floobydust:
It might be wired as an autotransformer, to provide a fixed voltage boost to cover line voltage sags. I have seen that in UPS as well.
I would inject say 6-12VAC into a winding and see what comes out.

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