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Author Topic: Power Supply Unit  (Read 44448 times)

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Offline kolias

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Re: Power Supply Unit
« Reply #70 on: January 15, 2011, 07:38:30 AM »
I’m planning this weekend to order the transformer and rectifier online and at the same time I would like to order the fuse and fuse holder

I think I will not install a fuse on the 110VAC incoming line but definitely I will have a fuse on the outgoing DC line.

Since my transformer has an output of 24VDC @ 10A (12V-0V-12V) should I get a 10A fuse or 15A or 20A?

Thanks
Nicolas
Re: Power Supply Unit
« Reply #71 on: January 15, 2011, 10:24:04 AM »
I’m planning this weekend to order the transformer and rectifier online and at the same time I would like to order the fuse and fuse holder

I think I will not install a fuse on the 110VAC incoming line but definitely I will have a fuse on the outgoing DC line.

Since my transformer has an output of 24VDC @ 10A (12V-0V-12V) should I get a 10A fuse or 15A or 20A?

Thanks


That is completely backwards.  Put the fuse on the AC input, NOT on the DC output.  If the fuse on the DC blows while the machien is moving, the back EMF frpm the motors can blow the stepper drivers.  Plus, with no fuse on the input side, if the transformer develops an internal short, you'll be completely unprotected, and could havd a fire.

Regards,
Ray L.
Regards,
Ray L.
Re: Power Supply Unit
« Reply #72 on: January 15, 2011, 10:42:22 AM »
Antec has rectifier modules on ebay -  $25 For 50v 30A ,or 80V 25A. Probably the best way for you to go.
Visit his store and you will also find fuse modules

Offline kolias

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Re: Power Supply Unit
« Reply #73 on: January 15, 2011, 04:01:44 PM »
Thank you Ray, it shows how much I know about power supply units LOL.

So I will only install a fuse on the incoming AC (black wire). Since this is 110VAC, 15A circuit should I put a 15A fuse? perhaps less?

And how you install a fuse on the 110VAC? with the same fuse holder they sell for the DC circuits? or perhaps a 15A breaker?

Richard thanks for the tip but we have settled the bridge rectifier; Hood suggested earlier a 400PIV, 25A which I will purchase from mpja.com at $2.70 (item #5248 BR)
Nicolas
Re: Power Supply Unit
« Reply #74 on: January 15, 2011, 04:10:35 PM »
Thank you Ray, it shows how much I know about power supply units LOL.

So I will only install a fuse on the incoming AC (black wire). Since this is 110VAC, 15A circuit should I put a 15A fuse? perhaps less?

And how you install a fuse on the 110VAC? with the same fuse holder they sell for the DC circuits? or perhaps a 15A breaker?

Richard thanks for the tip but we have settled the bridge rectifier; Hood suggested earlier a 400PIV, 25A which I will purchase from mpja.com at $2.70 (item #5248 BR)


The primary power will be roughly equal to the secondary power.  Since the secondary is 24V/10A, that's 240W.  Since the input is 120V, the input current will be roughly 240W/120V = 2A.  You want to use a larger fuse, for some safety margin, so I'd go with something in the 3-5A range.  You'll also NEED a slow-blow fuse, to prevent it from blowing due to the turn on transient caused by the large capacitors.  Use a 3AG style fuse, and any style holder that will accomodate it, and is rated for >120V AC, will be fine.

Regards,
Ray L.
Regards,
Ray L.

Offline kolias

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Re: Power Supply Unit
« Reply #75 on: January 15, 2011, 04:28:01 PM »
Thank you Ray, much appreciated
Nicolas

Offline kolias

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Re: Power Supply Unit
« Reply #76 on: January 15, 2011, 04:43:50 PM »
Sorry Ray to bother you again; I found the fuse holder but all the fuses are “fast blow general use electronic type” and either 2A, 4A, 5A etc. There are no slow blow fuses

Fuse Holder
http://www.mpja.com/prodinfo.asp?number=4476+FH

Fuse
http://www.mpja.com/prodinfo.asp?number=15781+FU

Would you happen to know any other place I can purchase them?

Thanks
Nicolas

Offline Hood

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Re: Power Supply Unit
« Reply #78 on: January 15, 2011, 05:00:40 PM »
Never made it to the workshop today, hopefully tomorrow I will and will try and remember to look for the caps.
Hood

Offline kolias

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Re: Power Supply Unit
« Reply #79 on: January 15, 2011, 11:00:23 PM »
Updated schematic for comments
Nicolas