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60 Hz Transformer in 50 Hz
3

60 Hz Transformer in 50 Hz

60 Hz Transformer in 50 Hz

(OP)
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?"

RE: 60 Hz Transformer in 50 Hz

it will have a lower impedance than on the nameplate.

RE: 60 Hz Transformer in 50 Hz

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 *

RE: 60 Hz Transformer in 50 Hz

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.  

RE: 60 Hz Transformer in 50 Hz

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

RE: 60 Hz Transformer in 50 Hz

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.    

RE: 60 Hz Transformer in 50 Hz

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)

RE: 60 Hz Transformer in 50 Hz

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

RE: 60 Hz Transformer in 50 Hz

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.

RE: 60 Hz Transformer in 50 Hz

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.   lol

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: 60 Hz Transformer in 50 Hz

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

RE: 60 Hz Transformer in 50 Hz

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

RE: 60 Hz Transformer in 50 Hz

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

RE: 60 Hz Transformer in 50 Hz

Keith!

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

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: 60 Hz Transformer in 50 Hz

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

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: 60 Hz Transformer in 50 Hz

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

RE: 60 Hz Transformer in 50 Hz

smile  smile  smile

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: 60 Hz Transformer in 50 Hz

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

RE: 60 Hz Transformer in 50 Hz

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

RE: 60 Hz Transformer in 50 Hz

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.

RE: 60 Hz Transformer in 50 Hz

Keith;
Shirly you haven't forgotten this lesson on power systems.

Quote:

The Beer Analogy
KVA is Apparent Power.
It is the "vectorial summation" of KVAR and KW.
Let's look at a simple analogy in order to better understand these terms....
Let's say you are at the ballpark and it is a really hot day. You order up a mug of your favorite brewsky.
The thirst-quenching portion of your beer is represented by KW (Figure 1).
Unfortunately, life isn't perfect. Along with your ale comes a little bit of foam. (And let's face it...that
foam just doesn't quench your thirst.) This foam is represented by KVAR.
The total contents of your mug, KVA, is this summation of KW (the beer) and KVAR (the foam).
http://www.nakahoma.com/POWER_FA.PDF
Sorry, I meant to stop calling you surely.
Sorry Gunnar, the devil made me do it.

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

RE: 60 Hz Transformer in 50 Hz

Surely we will both fail this interview, Keith.

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

RE: 60 Hz Transformer in 50 Hz

Saturation may be explained by the "Toilet Bowl analogy".
Think of a dry toilet bowl. Now imagine that it is being filled. Consider the depth of fluid to represent the voltage and the surface area to represent the current density.
As the fluid starts to rise in the bottom part of the toilet, the surface area stays relatively constant. This represents operation at voltages below the saturation voltage.
As the level increases, the toilet bowl starts to flare out, and the surface area starts to increase. This represents the increase in current as the voltage approaches saturation.
The toilet fills faster at 60 Hz. than at 50 Hz.

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

RE: 60 Hz Transformer in 50 Hz

Wait now I am confused, wouldnt it fill faster at 50 Hz than 60 Hz per the V/Hz analogy?

RE: 60 Hz Transformer in 50 Hz

You are probably right Zogzog.
I think that I have just failed toilet flushing 101.
flush

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

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