Optimizing a transformer for both 50 and 60Hz 1

[IvarA]

Something I have wondered on for a while:
Lets say you have a big transformer that will be used on both 50 and 60 Hz. i.e. a land-supply transformer on a ship.
When you make the transformer you would select the optimum transformer frequency to be somewhere in between. At first, one would think that 55Hz would be it. However, 50 to 55Hz is a 10% increase, but from 55 to 60 Hz it is 9.09%.

To find the right frequency f I put this equation:
50*x=f
60/x=f

then 50*x = 60/x

so x is sqrt(60/50)

And the frequency f would be 50*sqrt(6/5)=54.77

Not a big change, but I really wonder what would be the best. I thought about the problem for other engineering cases too, with wider operating conditions.

 

[MacGyverS2000]

Why would that equation hold to the question "what is the best frequency"? You've simply created a ratio but provided no reasoning behind its purpose.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[itsmoked]

IvarA; I don't believe you would build a transformer "somewhere in between". The reason is because an 'optimal' transformer has a barely big enough magnetic circuit to just work at the designed frequency. Using a lower frequency will cause it to saturate whereas using it at a higher frequency will not. This means you would build the transformer to be 'optimal' at the lower frequency which means it will certainly work at the higher frequency too - not halfway between the two.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Skogsgurra]

Ivar, can't be done. If you want to run a transformer at two different frequencies (and perhaps also different voltages) you simply have to use windings with taps that fit the different frequency/voltage combinations. Or build a transformer that can handle the lower frequency at its highest voltage and then be satisfied with a not-so-optimal utilization at the higher frequency.

Stadt?

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[IvarA]

MacGyver2000 - you are right, Ive should have said most efficient.

itsmoked - Makes sense to me! I remember those 400Hz transformers we had at work was pretty small compared to their rating. They were used transmitting power to underwater ROV's. Guess they would saturate quickly at lower frequencies.

I havent been deep into transformer theory, but i have installed many bobbins and torodials and im pretty sure they say 230v 50-60Hz, even if they only got one Primary.

Thanks for answers.

 

[waross]

An AC solenoid coil will saturate and burn out at over voltage.
An AC solenoid coil may not develop enough force to pull in at low voltage.
A solenoid coil rated for 230 Volts 50-60 Hz will have enough impedance at 50 Hz to prevent burnout at 230 Volts and will generate enough force to pull in at 60 Hz, 230 Volts although the Volts/per/Hertz relationship tells us that normally the proper voltage at 60-Hz is 230 x (6/5) or 276 Volts.
A a solenoid coil designed for use only at 230 Volts, 50 Hz may need as much as 276 Volts at 60 Hz to pull in.

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

 

[VEBill]

"...a land-supply transformer on a ship."

I guess you'd have to go through the entire ship to make sure everything connected to this supply is compatible with 50/60 Hz.