50Hz, 415V and 60Hz, 220V system 1

[elecengg010]

What is the difference in the design of transformer and motor (core and windings) in US (220V,60Hz) and India (415V, 50Hz)?

 

[waross]

The Volts per Hertz ratio.

Bill
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"Why not the best?"
Jimmy Carter

 

[waross]

And history.
220V,60Hz went out about a half a century ago.
A standard motor voltage is 230 Volts to be used on a standard system voltage of 240 Volts.
230V,60 Hz = 3.83 Volts per Hertz.
415V,50 Hz = 8.3 Volts per Hertz.
Note; 230 Volt motors are often dual voltage and usable at 460/480 Volts with a V/Hz ratio of 7.67 Volts per Hertz.
Also, motors intended for European markets tend to have one winding per phase for star or delta connection for a dual voltage ratio of 1.73:1
Motors intended for North American markets tend to have two windings per phase for series or parallel connection for a dual voltage ratio of 2:1

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

 

[elecengg010]

How are losses and core size and lamination thickness different in the two cases for transformers?
At some places I have read that core losses increase in case of 60Hz.
But I think it should decrease in case of 60Hz.

 

[ScottyUK]

Magnetic losses are complex. Lower flux density should result in lower losses, and for a given core as frequency rises the flux density reduces so your logic is correct up to this point. However losses actually occur each time the magnetic domains reverse, which is frequency-dependant, so it is also possible that losses increase as frequency rises. The actual behaviour at any specific frequency depends on the core operating conditions.

 

[waross]

When smaller equipment from a 50 Hz system is to be used on a 60 Hz system, or 60 Hz equipment for 50 Hz use, any change in core losses is generally ignored. For motors the change in load characteristics is important especially for unit pumps and fans.
The results are generally:
Maximum rated current; the same.
Maximum rated voltage; changes in the ratio of Hz₂/Hz₁ For 60Hz to 50 Hz, 50/60
Maximum rated KVA or HP; changes in the ratio of Hz₂/Hz₁ For 60Hz to 50 Hz, 50/60
Speed for motors; changes in the ratio of Hz₂/Hz₁ For 60Hz to 50 Hz, 50/60
A dual rating of 110V, 50Hz/120V, 60Hz is common on a lot of small control equipment. eg; Contactor coils, some control transformers, small motors such as shaded pole or verry small synchronous motors.
I do not intend to contradict ScottyUK in any way. I generally work on small equipment, about 1 MW or less. Scotty works on equipment in the MW range. Size matters and effects that are ignored or not even noticed on small equipment become serious issues on the big stuff.

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