230v 800va toroid on 115vac

InlineTwin · 28th April 2010, 04:34 PM

I have a 230V single primary toroid transformer with 50-0-50 output. I would like 25-0-25 output and I don't have 230V input. So is there any issue with using the available 115V to get the desired output?

AndrewT · 28th April 2010, 04:37 PM

Hi,
running a transformer at half voltage will reduce the VA by half as well, i.e. the current output rating remains the same.

InlineTwin · 28th April 2010, 04:46 PM

Thanks.

Tony · 2nd May 2010, 08:01 PM

Quote:

Originally Posted by AndrewT

Hi,
running a transformer at half voltage will reduce the VA by half as well, i.e. the current output rating remains the same.

only secondary voltage is halved, you should be able to get the same power output,

woody · 2nd May 2010, 08:57 PM

No the power output is halved. One of the major limitations on the power handeling
is the heat caused by the I R power loss and this loss will be the same at 115v or
230v.

Tony · 09:05 PM

power delivery is a function of the physical dimensions of the core, and as far as i can see, it did not change....only the input voltage has changed....

yes, copper losses will set you back....but not half va's worth...

chipnho · 3rd May 2010, 03:35 AM

Quote:

Originally Posted by Tony

power delivery is a function of the physical dimensions of the core, and as far as i can see, it did not change....only the input voltage has changed....

yes, copper losses will set you back....but not half va's worth...

than tang

AndrewT · 3rd May 2010, 09:32 AM

the current is limited by the primary copper resistance, by the core size and by the secondary copper resistance.
These all give heat.

If you reduce the primary voltage by half you reduce the core losses slightly. If you take out the same current then the Isqrd R losses are identical.

If the VA is set by maximum internal temperature then effectively the half voltage transformer is limited to it's original secondary current rating, i.e half power.

Tony · 3rd May 2010, 07:56 PM

power draw is determined by the load connected to the transformer's secondary, not it's specs per se....

event horizon · 3rd May 2010, 08:04 PM

Quote:

Originally Posted by Tony

power draw is determined by the load connected to the transformer's secondary, not it's specs per se....

So what you are saying is it's fine to overload the primary & secondary windings by drawing twice the current they were designed to supply?

I don't think so

Rewind the transformer with thicker primary & secondary windings & yes you'll get double the current with half the primary voltage, but then you'd have a 120V transformer anyway

28th April 2010, 04:34 PM	#1
InlineTwin diyAudio Member Join Date: Jan 2008	230v 800va toroid on 115vac I have a 230V single primary toroid transformer with 50-0-50 output. I would like 25-0-25 output and I don't have 230V input. So is there any issue with using the available 115V to get the desired output?

28th April 2010, 04:37 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, running a transformer at half voltage will reduce the VA by half as well, i.e. the current output rating remains the same. __________________ regards Andrew T.

2nd May 2010, 09:02 PM	#6
Tony diyAudio Member Join Date: May 2003 Location: Palatiw, Pasig City	power delivery is a function of the physical dimensions of the core, and as far as i can see, it did not change....only the input voltage has changed.... yes, copper losses will set you back....but not half va's worth... __________________ http://www.electronicslab.ph/forum/i...?topic=32688.0 Last edited by Tony; 2nd May 2010 at 09:05 PM.

3rd May 2010, 09:32 AM	#8
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	the current is limited by the primary copper resistance, by the core size and by the secondary copper resistance. These all give heat. If you reduce the primary voltage by half you reduce the core losses slightly. If you take out the same current then the Isqrd R losses are identical. If the VA is set by maximum internal temperature then effectively the half voltage transformer is limited to it's original secondary current rating, i.e half power. __________________ regards Andrew T.

3rd May 2010, 07:56 PM	#9
Tony diyAudio Member Join Date: May 2003 Location: Palatiw, Pasig City	power draw is determined by the load connected to the transformer's secondary, not it's specs per se.... __________________ http://www.electronicslab.ph/forum/i...?topic=32688.0


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28th April 2010, 04:46 PM	#3
InlineTwin diyAudio Member Join Date: Jan 2008	Thanks.

2nd May 2010, 08:57 PM	#5
woody diyAudio Member Join Date: Jan 2002 Location: Tyrone Ga. U.S.A.	No the power output is halved. One of the major limitations on the power handeling is the heat caused by the I R power loss and this loss will be the same at 115v or 230v.

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