Select 460V to 208V transformer
Select 460V to 208V transformer
(OP)
For a 15 HP motor, 208V, six lead three phase motor that is wound for 208V delta or 416V star, what is the best low cost selection for a transformer 460V primary and 208V secondary so that the motor can be run on 208V?





RE: Select 460V to 208V transformer
You need to spec your requirements, especially copper vs. aluminum. Outdoor/ indoor, temperature rise etc.
Look up the standard features offered and review that thye meet your needs.
Rafiq Bulsara
http://www.srengineersct.com
RE: Select 460V to 208V transformer
RE: Select 460V to 208V transformer
There are no motors wound for 208V delta/416V star.
If you can't accurately describe your equipment, I don't want the responsibility of advising you.
Bill
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"Why not the best?"
Jimmy Carter
RE: Select 460V to 208V transformer
Per what Bill said, a decent industrial electrician will know this and be able to properly select and connect some buck-boost transformers for you.
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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RE: Select 460V to 208V transformer
I wish they were!! A true 415V motor in the UK is a 'special' now, which is a real PITA when you work on a site with legacy infrastructure and don't have the ability to get down to 400V on taps.
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If we learn from our mistakes I'm getting a great education!
RE: Select 460V to 208V transformer
The motor shop offered to rewind the motor for 460V at a reduced cost,we'll probably go that way. The customer is maxed out on 208V current but has plenty of 460.
I witnessed the motor shop test the Siemens motor on 416V and 460V. For the record, the motor shop's motor test stand uses a commercially made power supply box and one of the choices for voltage output selection was 416V. Just because 460V is not used in our country does not mean that it does not exist. Its a big world!
RE: Select 460V to 208V transformer
208V and 480V are both standard North American voltages. The standard motor voltages for use on 208V and 480V are 200V and 460V respectively.
A star delta motor for use on 200V would be rated either 200V/346V or 200V star delta/start.
The other option may be 230V/400V or 230V star delta start.
And it is possible to build a motor for 460V and underrate it so that it will have enough torque to develop full horsepower at 208V delta. Kind of wasteful for a 15HP motor.
But,thinking outside the box;
A 208V delta motor would want 360V on the star connection. 15 HP will need about 25 Amps at 360V. Two 480:120V dry type transformers in buck configuration will drop your standard 40V t0 360V. There will be 25 Amps in the 120V windings so you will need two 3KVA transformers in open delta.
If you are subject to heavy loading and/or frequent starting use 5KVA transformers.
May be cheaper than a rewind, depends on the labor cost to install.
Where are you located. In North America 460 went out as a standard voltage in the 50's. I saw a legacy 460 Volt transformer about 10 years ago, but there are not many legacy 460V systems left. If a transformer fails you will most likely be upgraded to 480 Volts. 480 Volt transformers are available off the shelf. A 460 Volt transformer may be a special build with a long delivery time.
Bill
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"Why not the best?"
Jimmy Carter
RE: Select 460V to 208V transformer
RE: Select 460V to 208V transformer