General ? On Dual Primary Transformers - Double UP?

Super_BQ · 26th July 2004, 02:58 AM

This question might be related to 50/60Hz cycle on transformers.

Let's take a toroidal transformer with the following description:

Dual Primary: 115/230VAC
Dual Secondary: 0-18 & 0-18

From a 230VAC mains power source. We would SERIES the primary and to get 0-36 volts on the secondary we would series them also.

My question is, would it be safe to run 230VAC if we PARALLEL the primary so we can get double the voltage output on the secondary? What impact would doing this have? (more noise?)

BQ

jh6you · 26th July 2004, 07:10 AM

As far as I understand, the transformer will anyhow keep its original maximum power rating. If so, doubling up the voltages as you plan will pull the maximum current rating down to half.

moamps · 26th July 2004, 07:52 AM

Quote:

Originally posted by Super_BQ
My question is, would it be safe to run 230VAC if we PARALLEL the primary so we can get double the voltage output on the secondary?

No.
Usually, you will destroy transformer.

Regards
Milan

AudioFreak · 26th July 2004, 08:34 AM

Quote:

Originally posted by Super_BQ
My question is, would it be safe to run 230VAC if we PARALLEL the primary so we can get double the voltage output on the secondary? What impact would doing this have? (more noise?)

Unless you specifically know otherwise with the transformer in question, the answer is no. The usual effect is destruction of the transformer.

jh6you · 26th July 2004, 09:37 AM

Audiofreak,

Is the destruction happening due to increased current in primary side? Or, is the story more complicated? Thanks.

kilowattski · 26th July 2004, 10:20 AM

I don't understand why the transformer would be destroyed? Maybe someone could explain that to me. The only reason I can think of is that the primary current would be doubled and the primary windings may not be able to handle the extra current.

moamps · 26th July 2004, 10:30 AM

Quote:

Originally posted by kilowattski
I don't understand why the transformer would be destroyed? Maybe someone could explain that to me. The only reason I can think of is that the primary current would be doubled and the primary windings may not be able to handle the extra current.

Hi,

You can find some infos here:
http://www.allaboutcircuits.com/vol_2/chpt_9/11.html

Regards
Milan

dnsey · 26th July 2004, 10:34 AM

Depending on how it's wound, the primary winding might not be designed for the resulting voltage gradient, leading to insulation breakdown, shorted turns, and a possible fire hazard.

jh6you · 26th July 2004, 11:08 AM

Thanks, moamps!!!

moamps · 26th July 2004, 11:29 AM

Quote:

Originally posted by jh6you
Thanks, moamps!!!

26th July 2004, 02:58 AM	#1
Super_BQ diyAudio Member Join Date: Sep 2001 Location: New Zealand / Canada	General ? On Dual Primary Transformers - Double UP? This question might be related to 50/60Hz cycle on transformers. Let's take a toroidal transformer with the following description: Dual Primary: 115/230VAC Dual Secondary: 0-18 & 0-18 From a 230VAC mains power source. We would SERIES the primary and to get 0-36 volts on the secondary we would series them also. My question is, would it be safe to run 230VAC if we PARALLEL the primary so we can get double the voltage output on the secondary? What impact would doing this have? (more noise?) BQ __________________ Yellow People for a Yellow World Vote for Super_BQ, the Asian Alternative

26th July 2004, 10:20 AM	#6
kilowattski diyAudio Member Join Date: Aug 2003 Location: Long Island, New York	I don't understand why the transformer would be destroyed? Maybe someone could explain that to me. The only reason I can think of is that the primary current would be doubled and the primary windings may not be able to handle the extra current. __________________ ----------------------------------------------- Kilowattski

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26th July 2004, 07:10 AM	#2
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	As far as I understand, the transformer will anyhow keep its original maximum power rating. If so, doubling up the voltages as you plan will pull the maximum current rating down to half.

26th July 2004, 09:37 AM	#5
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	Audiofreak, Is the destruction happening due to increased current in primary side? Or, is the story more complicated? Thanks.

26th July 2004, 10:34 AM	#8
dnsey diyAudio Member Join Date: Mar 2004 Location: Shropshire, England	Depending on how it's wound, the primary winding might not be designed for the resulting voltage gradient, leading to insulation breakdown, shorted turns, and a possible fire hazard.

26th July 2004, 11:08 AM	#9
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	Thanks, moamps!!!

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