earlier i was working in India where the line frequency was 50hz & now in middle east it is 60hz. can you tell me why the voltage rating is changed with frequecy cycle, as 33kv has changed to 34.5 kv 11kv has changed to 13.8kv? Same way calculating the current rating of motors is also varys comparing 50hz/60hz. Pl solve this puzzle.

1) Is it can be used 60hz to 50hz or 50hz to 60hz.
2) How to calculate the single phase and three phase power ratings or the ampere rating with frequency changes.
3)What are the formulas to calculate.

 

Most of the differences are due to the magnetics involved. A 50 Hz magnetic component needs more copper or more iron or both to have the same inductance. Many secondary and tertiary effects come into play and exact calculation would be specific to a particular piece of equipment. These low frequencies were originally chosen so AC wiring "behaved" more like DC. Higher frequencies are used when efficiency is paramount, but would make distribution much more problematic. You'll find the per cent change in ratings is often similar to the per cent change in frequency.

Regards

cww