Three-phase power supply US?

[Henas87]

I am working on getting a breathing air system approved for use in North America.

This is a brand new market for me, and i have a basic questions.

I am trying to find out what the most commonly used three-phase powersupply is onshore and offshore?

Thanks in advance.

 

[waross]

120/208 Volts wye
277/480 Volts wye
In Canada;
347/600 Volts wye
Occasionally 240 Volts delta and 480 Volts delta. Delta service is not available in many areas.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Henas87]

And these voltages apply to both onshore and offshore?

Is it accurate to say that 480v is the standard for motors aswell?

 

[itsmoked]

What do you mean by offshore?? Offshore typically means "other countries". If you mean on a pier or something there's no real difference.

No it is not fair to say 480V is the standard for motors. Probably 2/3rds of all motors are 208 or 240.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

In the European area 'offshore' typically means on a platform in the middle of the sea. The North Sea is a hostile place for anything, and especially anything electrical.

"Other countries" are 'abroad'. Divided by a common language!

 

[jraef]

So if it is a breathing air system, and you are asking about "off shore", we can guess that this is for underwater equipment, such as SCUBA tank filling, or dive suits, or mini-subs? If that's the case, you may want to consider a single phase option. Many small commercial areas near docks will not have 3 phase power available.

If you want it to be more universally acceptable, you could consider using a VFD and a 208V 3 phase motor. That way if they have 208V, 3 phase, great, if they have 240V 3 phase, the drive is fine with 240V input and giving 208V output, and if the motor is 3HP or under, you can get a VFD that will accept 240V 1 phase or 3 phase input without derating. If they have 480V available, they will likely also have 120/240V single phase available as well for lighting and other single phase loads.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[waross]

I suggest selecting a motor rated for 230/460 Volts. (230 Volts and 460 Volts are the standard voltage ratings for motors used at 240 Volts and 480 Volts.
If there is more than occasional air required, the power requirements may be too great for the reasonable use of single phase.
In the smaller sizes there are motors available that are rated for 200:230/460 Volts or 208:230/460 Volts. If you will be over about 10HP or 15HP you may want to consider a 230/460 Volt rated motor slightly oversized so as to be able to function properly on nominal 208 Volts on a day when the voltage is at the lower limit of the utility's voltage tolerance range.
Another option may be to include a pair of auto-transformers in open delta boost configuration to boost 208 Volts up to 240 Volts for 208 Volt applications.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[melspuds]

480V wye or delta systems are the most common Low Voltage in industrial settings. 208V or 240V systems are mostly light industrial loads. 208V systems are normally used in offices, schools, ect.
NOTE: Motor nameplate voltage is listed as 230V nominal for 240V systems. And 460V nominal is listed as for 480V systems.
Sometimes 200V or 208V is listed for 208V systems. Common 3 phase motors are dual voltage in smaller sizes, meaning that the windings either field wired for series (higher voltage) or parallel (lower voltage)and listed as 230/460V.
Hope this helps and good luck,
Dave

 

[Henas87]

Thanks for all the replies.
If any of you wonder what kind of a system i am talking about you can check out

http://www.pusteluft.no

As ScottyUK says, when i say offshore i mean on platforms and installations in the sea I cant believe I didnt realise there was a difference!

230/460v 7,5HP is what I need then. I have compared IEC frames(112) to NEMA frames and found that I need a 184T frame.

A question on the side: Hazardous locations. I am used to the IEC 3-zone system, the class/div is new to me. As Class1 div1 involves both zone 0 and 1, is it given that a Class1 Zone 1 certified equipment would be rejected at a class1 div1 site, or would it be sujected judgement by authority having juristiction?