3 Phase Voltage Levels

[hash80]

Here what I have confusion:

What 3 phase actual voltage should be? 400 or 415 or 480 or 440, 380 Volts at 50 Hz. for calculations both design and running conditions.

What makes these levels vary?

 

[jpatricksss]

IEC 60038 Standard Voltages:

Three-phase 50 Hz
230 V / 400 V
400 V / 690 V
1000 V
Suppliers using 220 V / 380 V or 240 V / 415 V systems were expected by the standard to migrate to the recommended value of 230 V / 400 V by the year 2003. This migration has already been largely completed, as least within the European Union.

Three-phase 60 Hz
120 V / 208 V
240 V
277 V / 480 V
480 V
347 V / 600 V
600 V
One-phase, three-wire 60 Hz
120 V / 240 V

 

[rbulsara]

Design voltage is dictated by the existing system voltages, local codes and wish of the designer within limits of the codes.

Although there are "standard' voltages, which more common in a country or region, it is not illegal to have different voltages but many non-technical reasons may not make them a wise choice.

What makes it vary? - Long history, development of separate systems before they were interconnected. Evolution of standards and harmonization, which is still an on going process.



Rafiq Bulsara

http://www.srengineersct.com

 

[waross]

Further to Rafiq's post, I service a small generating station that was built with second hand equipment so old that the transformers were 460 Volts instead of 480 Volts because that was the standard voltage when the transformers were built. When one burned out, we had to replace it with a 480 Volt transformer with the taps turned down to 456 Volts. The better regulation of the newer transformer made it a good match under load. That was about 12 years ago. The other two transformers may be changed out for 480 Volt units by now.

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