From Newsgroup: sci.electronics.equipment


Setting up a new shop, but will need a 220 line for servicing some high
power equipment.

This transformer sits on the floor near the breaker panels:

General Electric 9T23B3872 https://www.rexelusa.com/p/193724/abb/transformer-dry-type-30kva-480-delta-primary-208y-120v-secondary-/783173004920/9t23b3872

Specs say it steps down 480 to 120 and 208.

Is 208 gonna work for 220? Never heard that voltage mentioned in my travels.

The 120V wall outlets read about 123V on the DMM, sort of high than where I was previously.

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From Newsgroup: sci.electronics.equipment

On 2026-02-28 10:55, UFO wrote:

Setting up a new shop, but will need a 220 line for servicing some high power equipment.

This transformer sits on the floor near the breaker panels:

General Electric 9T23B3872 https://www.rexelusa.com/p/193724/abb/transformer-dry-type-30kva-480-delta-primary-208y-120v-secondary-/783173004920/9t23b3872

Specs say it steps down 480 to 120 and 208.

Is 208 gonna work for 220? Never heard that voltage mentioned in my
travels.

The 120V wall outlets read about 123V on the DMM, sort of high than
where I was previously.

Hopefully you have a real electrician coming to do the
installation--480V mains power is no joke whatsoever.

208 is the nominal voltage across two phases of a three-phase feed. |240*sin(120 degrees)| = 207.85.

I once had an actual electrician mistakenly connect 208 to a 240V
single-phase load (a brand-new, fancy lamp-pumped Nd:YAG laser). This effectively browned out the internal switching converter, resulting in overcurrent large enough to cause the (underrated) fuseholder to catch fire.

Exciting times in the lab. :(

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

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