2000va multitap transformer. Suggestions?

[Alexontherocks]

Hi all.

I have been using for some time now a Large transformer rated 2000va featuring multiple secondaries. Only for high current experiments (peltiers, solid state lasers ecc)

An externally hosted image should be here but it was not working when we last tested it.

The secondaries range in discrete steps from 6v to 180v.

I really have no use now for it since for all experiments I use a 2000va variac.

I was hoping this transformer could be transformed for audio use. It is very heavy (25kg) but for a static installation it might be used.

unfortunately the windings are as such:

0-6 to 0-180 so no dual voltages with center tap seem available.


I am currently exploring tube amp construction and since I would have a 180v + 60v + 6v it might make sense to use it for an enormous PPP design (something like a mesa boogie but on a larger scale).

An externally hosted image should be here but it was not working when we last tested it.

I also own several 2000uf 200v caps I could use in a build such as this.

Anyways any suggestions would be very welcome. Fire away with any ideas!

Thanks

Alex

 

[Alexontherocks]

I was actually thinking of doing something like so:

An externally hosted image should be here but it was not working when we last tested it.

However some good input form you guys is what I really need.

Thanks!

 

[Alexontherocks]

On other detail and I hope someone can offer some help on this one:

The input wires are green on the transformer. I have 4 leads

1. 210
2. 0
3. 230
4 30

What is the 30v for? is there anyway I can use this input to elevate all the secondary outputs?

Thanks
Alex

 

[AndrewT]

Alex,
are all 4 tappings on the one Primary Winding?

 

[Alexontherocks]

You know sometimes I should really test and test over again before writing....

the 4 wires are all green aas opposed to the secondaries which appeared to be yellow..

However there is no continuity between the 30v (green) and 230(green) but there is between the 0v (green) and the 230v (green).


basically the 230 + 0 green inputs are one large input

the secondaries therefore range from 0 to 210v (with a color change from yellow to green at 210v) also there is an extra 30v green wire.

So basically I have a

0 yellow
6 yellow
12 yellow
24 yellow
30 green + 30 yellow
60 yellow
90 yellow
120 yellow
150 yellow
180 yellow
210 green


All the outputs in bold show continuity.

 

[Alexontherocks]

yes...continuity between all yellow leads and yellow + 30v/210v green leads.


NO continuity between all the above values and the 0 - 230v input leads

 

[AndrewT]

there is no continuity between the 30v (green) and 230(green) but there is between the 0v (green) and the 230v (green).

basically the 230 + 0 green inputs are one large input

is this confirming you have only one Primary Winding? and that Primary has only two tappings?

I have a

0 yellow
6 yellow
12 yellow
24 yellow
30 green + 30 yellow
60 yellow
90 yellow
120 yellow
150 yellow
180 yellow
210 green


All the outputs in bold show continuity.

is this confirming you have one secondary winding with lots of tappings off the same single winding?

 

[Alexontherocks]

Yes. Also a visual prof of this is that all secondary leads are double which would be expected in case of taps along a single winding. would it not?

I confirm the 230 -0 input leads share no continuity with any other connection on the platic rail connectors.

 

[AndrewT]

The Double Wires going into each terminal may mean that the secondary has separate windings and that these separate (two ends to each winding) are connected in series.
Open up one terminal connection that has two wires and split them. Do you now measure two separate secondaries?

If you can, check the thickness of every wire going into the terminal block.
Check the resistance of every tapping.

Is the Primary on a separate bobbin from the secondary?

 

[Alexontherocks]

You see that is why I love thi forum....always learning something new.

The secondaries appear in series. I f a open up the 30v yellow double lead I get no continutuity between the 24v and the 150v (for example). THis is so for every double lead.

The thickness is almost 2mm OD per wire...

Unfortunately I do not have a thickness gauge here but I would say 2mm is pretty a ccurate (simple metallic ruler used)

 

[AndrewT]

If they are all 2mm diam then they are all the same current rating.
Your eye can be very good at recognising a difference in diameter if the wires are the same colour. I can see the difference between a Weber 150 jet and a 155 jet. That is a difference of 0.05mm in a diameter of 1.5mm

Can you split up the secondaries and give every end it's own exclusive terminal?
Now recheck for continuity of each winding and isolation of each winding from every other. Be thorough, label every end. I find it easier if screw down insulated terminal block grips each enameled wire. It bites through the enamel to help with that testing.
Check again that every secondary is isolated from the Primary.

Now you should have a set of 6Vac and 12Vac and 30Vac windings.

You can combine them into dual equal voltage pairs and/or combine them into centred tapped pairs. You now have a transformer that can drive almost every project.

Don't expect good isolation between the individual secondaries. It depends on how they have wound every turn. Some may only have two layers of enamel insulation between windings. If one of these enamel coatings is cracked or scraped or damaged then you are left with just one layer of enamel as your isolation insulation.

 

[Alexontherocks]

Thanks Andrew!

I actually also found a 2kva 55-0-55 transformer (25kg! more or less) and several large microwave transformers.

I can scavenge parts like no one! 😀