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Message started by deucekazoo on 05/17/19 at 17:00:47

Title: Transformer
Post by deucekazoo on 05/17/19 at 17:00:47

A while back my company was recycling a lot of their unused stuff. One day one of the guys asked me if I could look at something and let him know what it was, that it looked like a big donut. The donut was a huge toroidal transformer. It was a power supply from a server rack. So I save this thing from the recycling place. I had it sitting in the basement for a while but after reading comments on the new (ZLC) I pulled it out just to see if it would even power up. I dragged it into the garage and put a welding plug on it so I could test it. Plug it in and everything works like it should. This thing runs on 240V and it weighs 120 pounds with most of the weight being the transformer. So I decide to run a 240V line to my room. That is why I love conduit for wiring a house. Pulled old wires out and pulled 4 new 10 awg wires into my outlet by my audio. Plug all my stuff in and everything works! The only thing I am fighting right now is the noise. There are two fans on the Power Supply and one runs all the time. I bought one quieter fan that runs on 120V, but it is still too loud. So I unplugged all of them and watched the temperature. It hit 121 degrees F  after a few hours of running the audio stuff. Not sure if that is too hot for the transformer or not. I am looking into other fan options that run on USB power that only produce 18 db of noise when running with a controller and temp probe. That will probably be the next step to see if I can get this quiet enough. Just to mention you can not hear the fans now during music, its only between songs.
So just wanted to mention my latest experiment. I have not done any test yet to see if it improved the sound compared to the basic 120V outlet. I want to get the fan issue fixed first before I do anything else.
Also let me know if anyone knows the safe temp of a transformer. The transformer has an output of 120v 5000VA, its huge.  
Thanks,
John

Title: Re: Transformer
Post by deucekazoo on 05/17/19 at 17:02:15

Picture of the power supply.

Title: Re: Transformer
Post by Archie on 05/17/19 at 21:55:48

This may not be big enough for your purposes but I mounted a computer fan behind my ZMA.  I keep it at a low speed and it's extremely quiet.  Even at it's highest speed its quiet enough.  It keeps the air from getting stagnant with a light breeze.  The ZMA transformers used to get in the low 120s before the Anniversary mods and adding the ZLC.  Now they run cooler and I doubt I even need the fan, if I ever did but I liked the peace of mind it gave.

Title: Re: Transformer
Post by bandrade on 05/18/19 at 02:27:40

John,
The transformer winding temperature rise above ambient would depend on the Class of insulation of the windings. The class of insulation should be listed on the name plate somewhere. At any rate even at the lowest class i.e. Class A insulation the acceptable temperature rise is 131 F. Note this is the temperature rise above ambient so you should be well covered at 121 F as that is your actual temperature inclusive of ambient. Note these readings are for new transformers. As the transformer ages its insulation deteriorates due to oxidation, but you should still be fine at 121 F actual temperature unless the transformer is 20 years old or more and even then it should be fine as you have a fair bit of margin but there is a chance that it will fail. The likely reason the temperature is somewhat lower without the fans is because you are running it well below its designed full load (5000VA - which is high).

BTW 131 F is for normal long life running. The max temperature for Class A insulation is 221 F above which the transformer will likely fail in a short time. And in between the two temps the life of the transformer decreases at you go up.

Looks like you are taking the temperature readings after a few hours of operation with the top removed and fans disabled. The winding temperature will be higher with the top back in place and fans disabled. Also if you load it higher with even more equipment being run off it the winding temperature will increase.

Title: Re: Transformer
Post by deucekazoo on 05/19/19 at 14:38:10

Archie,
I was thinking the same thing as to running the fan slower. Right now it runs at full speed and loudest possible. I ordered a speed controller for the fan from the same company. We will see if running it slower will drop the noise down enough.

bandrade,
Thanks for the explanation. When I took the temperature readings the cover was off but I have the unit placed under my component rack and there is only a 1/4" gap between the unit and the bottom shelf. Not the same as having the top on but still not fully open. I pulled it out a little to take the temp with one of those laser thermometers. The center of the transformer had the highest temp reading. I could probably run it like this but I would feel better having a little bit or air flow. I only had a CD, amp and pre-amp hooked up at the time, so the draw was probably minimal to what it would usually see running a server rack.

Guys, thanks for input.

John

Title: Re: Transformer
Post by deucekazoo on 05/21/19 at 14:15:14

So received the speed control and it worked. I originally thought the speed control would have 3 speeds (low, medium, hi) but it is variable. So plugged it in and dialed in the speed so the fan was quiet. It now has air flow and I can't hear it from the listening chair. Ran it for a few hours and checked the temp, which was 102 F. It should be good to go.

Title: Re: Transformer
Post by 4krow on 05/27/19 at 23:54:31

 John,

 I laughed when I saw this transformer. It's not just me that thinks this way! No doubt, this tranny will have no trouble with any system that you choose to hook up to it. What I like about the 220 volt input, is that noise is already being cancelled out (common mode noise, that is).
I bought a BPT power unit. It also uses a large transformer... well, only 80 lbs. but who's counting. In it's design, there are 6 separate secondary windings and shields, making each outlet less prone to noise transmission from other equipment.

 Anyway, just wanted you to know you have my vote for this piece... and, nobody can argue much about a lack of current supply using this transformer.
Lastly, good call using conduit that can handle larger wiring.

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