Question about Allied & Hammond Power Transformer Ratings

Bitrex · 4th March 2009, 07:41 AM

I'm wondering how Allied & Hammond rate their power transformers maximum current output - are the current maximums shown for both sides of the secondaries under load, or is that the maximum current that can be drawn in the standard center tapped arrangement where only one side of the transformer is under load at a time?

Jeb-D. · 5th March 2009, 01:50 AM

The transformer current rating is AC, from 1 end of the secondary winding to the other (not to center tap). The permisable average DC current draw is about equal to the AC rating, when using the standard full wave rectifier with capacitor input(centertap grounded, 2 diode config).

If your using bridge rectification (four diodes), the permissable DC current draw will be between .5 to .7 that of the transformers rating. However, your DC output voltage will be aprox. twice that of a full wave rectified.

read this
http://www.hammondmfg.com/pdf/5c007.pdf

I also recomend downloading PSUD2 for simulating power supplies. It's more accurate than the generalities I mentioned above.

pmillett · 6th March 2009, 08:31 AM

On the Allied and Hammond plate transformers, the HV secondaries are actually rated in DC mA using a full-wave rectifier (not bridge) and a cap-input filter.

You can a bit draw less current if using a bridge (I guess .5x to .7x is reasonable), and more using a choke-input filter.

Pete

4th March 2009, 07:41 AM	#1
Bitrex diyAudio Member Join Date: Jan 2009	Question about Allied & Hammond Power Transformer Ratings I'm wondering how Allied & Hammond rate their power transformers maximum current output - are the current maximums shown for both sides of the secondaries under load, or is that the maximum current that can be drawn in the standard center tapped arrangement where only one side of the transformer is under load at a time?

6th March 2009, 08:31 AM	#3
pmillett diyAudio Member Join Date: May 2005 Location: Dallas (but I am not a Texan!)	On the Allied and Hammond plate transformers, the HV secondaries are actually rated in DC mA using a full-wave rectifier (not bridge) and a cap-input filter. You can a bit draw less current if using a bridge (I guess .5x to .7x is reasonable), and more using a choke-input filter. Pete __________________ When life hands you a jeffery, stroke the furry wall.

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5th March 2009, 01:50 AM	#2
Jeb-D. diyAudio Member Join Date: Nov 2005 Location: SoCal	The transformer current rating is AC, from 1 end of the secondary winding to the other (not to center tap). The permisable average DC current draw is about equal to the AC rating, when using the standard full wave rectifier with capacitor input(centertap grounded, 2 diode config). If your using bridge rectification (four diodes), the permissable DC current draw will be between .5 to .7 that of the transformers rating. However, your DC output voltage will be aprox. twice that of a full wave rectified. read this http://www.hammondmfg.com/pdf/5c007.pdf I also recomend downloading PSUD2 for simulating power supplies. It's more accurate than the generalities I mentioned above.

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