60hz transformer on 50 hz 1

[rashy70]

We have one transformer 1000kVA,4.160kV/0.480kV,Delta/Star, 60Hz.If we coonect with 3.3 kV, 50 hz , will that work ? . I need to get 380 volts at secondary.

 

[RRaghunath]

Yes, I don't see any problem - 4.16/0.48kV, 60Hz should be same as 3.3/0.38kV, 50Hz from design point of view - frequency is 20% less and correspondingly primary and secondary voltages each are 20% less, math seems OK.

 

[dpc]

Turns ratio is OK and Volts/Hertz is OK, so it should work.

(I'm assuming you meant 480 V, not 480 kV)

But you won't have a 1000 kVA transformer any longer.

 

[MAGTiger]

dpc makes an important point. Your rated output current will remain the same as at the higher voltages so KVA is reduced by the same amount as the voltage reduction. However, your % impedance will increase.

Neil

 

[rashy70]

Load on the transformer will be less than 300kVA

 

[dpc]

Load on the transformer will be less than 300kVA

That's what they always say....

You should add a new nameplate indicating the reduced kVA rating.

 

[waross]

Isn't that the truth dpc. Been there, done that, Have the tee shirt. The tee shirt covers most of the scars. grin
The new KVA rating will be 1000 KVA x (3300/4160) = 793 KVA. Call it 790 KVA.
To calculate the new impedance you will have to know the X/R ratio of the transformer. It may be easier to just connect a Variac to the primary, short the secondary and measure the impedance voltage, if you need this information.

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

 

[prc]

rashy70, It will not work.Vice versa will.ie You can use a 50 Hz trf in 60 HZ grid.Voltage will not change with frequency as raghun is thinking.Applied voltage remains the same so the flux density in core will go up by 20 % when you connect to 50 Hz and in normally designed units it means transformer core will move in to saturation flux density regions. E=4.44fBAT 10E-08 where T=no of turns A=Area of core B =Flux density in core.

Imagine a case you have a 60 Hz trf with flux density 20 % less than normal.(today's trfs have 1.7 T as B)Then you can connect to 50Hz.You can work on the same kVA rating.But percenatge impedance will come down by 20 % so that voltage dip with loading will be less.

 

[edison123]

prc - you may want to reconsider.

Muthu

http://www.edison.co.in

 

[itsmoked]

prc; Yes you can use a 60Hz trafo in 50Hz land!!

But to reduce the flux density you have to reduce the voltage as described above.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[prc]

Gentlemen, Iam sorry.I made a mistake.rashy is planning to connect to -20 % less voltages.Then he can use it at 80 % of original kVA.

In real practical applications, it is always a FAQ with same voltages.Once again sorry for wrong answer.

 

[slavag]

Hi
AFAIK, very important only one thing:
U/f=const ( as Dave pointed)

Best Regards.
Slava

 

[waross]

RE impedance; The impedance is the vector sum of the resistance and the inductive reactance. The resistance remains unchanged but the inductive reactance is frequency dependent. You must know the X/R ratio to calculate the new impedance. Voltage dip with unity power factor loads is mostly dependent on the resistance. The voltage dip will be about the same (but not exactly) in volts, but will be greater when expressed as a percentage. Voltage dip is dependent on "REGULATION" and is mostly dependent on the R of the transformer. Symmetrical short circuit current is dependent on the "IMPEDANCE". Percent regulation is less than the percent impedance.

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