60 Hz Transformer in 50 Hz 3

[Dary67]

Can any body answer this common question in some technical interview:
" What will hapend to a 3 phase 60Hz transformer if supply with 50Hz and same voltage?"

 

[whycliffrussell]

it will have a lower impedance than on the nameplate.

 

[edison123]

It will saturate magnetically and the no-load current would shoot up. Excessive core heating would result.

* Women are like the police. They can have all the evidence in the world and yet they still want a confession - Chris Rock *

 

[dpc]

Just think in terms of volts/hertz. If this ratio goes up, as in this case, the core will probably saturate, as edison notes. Power transformers operate at flux densities very close to saturation.

 

[Zogzog]

Interesting dpc, can you explain that a little more in detail?

 

[dpc]

Changing from 60 Hz to 50 Hz at the same voltage effectively increases the V/Hz by 20%. If operating at rated voltage, many (most?) power transformer cores will become saturated at this level.

 

[Zogzog]

Sorry, I think you just reworded your 1st post, maybe I am having a complete brain fart here but I dont follow the V/Hz theory applied to transformers. (My guess is brain fart)

 

[itsmoked]

V/Hz speaks to the amount of magnetic flux required. A transformer's core size directly equates to how much magnetic flux it can hold while still giving a linear response. If you exceed that amount the inductance plummets, current skyrockets just before the transformer does. 60Hz transformers are physically 20% smaller than the equivalent 50Hz transformer.

Using a 60Hz in 50Hz land is a disaster. Using a 50Hz in 60Hz land is no problem.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Zogzog]

OK, hit the books, got it now, looking at a saturation curve again made the light come on, thanks for helping and making me (re)learn something today. My transformer theory was a little rusty.

 

[itsmoked]

Just look at the flux as being a bunch of spaghetti noodles. Only so many will fit into a given core. V/Hz => how many noodles.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[slavag]

Keith, Nice explanation!!!!!
Zogzog, it's usually problem in the generator step-up trafos, if AVR not work correct.

 

[Zogzog]

OK, I just unlearned everything I relearned today and more.

 

[slavag]

Zogzog, I learned it before one year after unwanted trip of step up trafo differential protection 87T.
Regards.
Slava

 

[Skogsgurra]

Keith!

This is supposed to be an Engineering site. Not a recipee exchange!

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[itsmoked]

Gunnar I left out the marinara sauce.. => magnetic domains.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[waross]

Keith, is there a direct (or inverse) correlation between the percentage of foam on the beer and the amount of spaghetti in the core? Does the spaghetti have to be cooked first?
LOL

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

 

[Skogsgurra]

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[itsmoked]

For proper modeling the spaghetti should be cooked first.

Beer? Yuck!
I only use it for killing snails.. Same thing it does to brain cells.

Oh, and the chickens have completely eliminated all snails. Haven't seen one in 4 years.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[capuchi]

itsmoked

you said using a 50Hz in 60Hz land is no problem. Question: What happens to the voltage on the secondary? Will it increase proportionately?

rick

 

[davidbeach]

Voltage ratio between primary and secondary (at power system frequencies) is only a function of the ratio of the number of windings. For a given kVA rating a 50Hz core (transformer or motor) will be larger than a 60Hz core. Voltage ratings still apply and since many 50Hz voltages are somewhat less than the 60Hz equivalent (400V vs. 480V, 11kV vs. 13kV, 400kV vs. 500kV, etc.) you may find you have voltage rating issues trying to use a 50Hz transformer for 60Hz applications but the core won't saturate.