Cost Performance Power Supply

Interesting.

What do you plan to use as a housing?

Way above my pay grade, but I've seen discussions regarding the type of wave and compatibility (or lack thereof) - how does this power supply fit into that? 

@carl552 posted:

The Antek An-6218-600VA 18V Toroidal transformer with Airpax Sanpac 10A instant trip breakers, PP11-0-10.0A-OB-V, is a good cost performance power source.  The $82 Antek An-6218-600VA has four 18V 8.3A outputs.  Four Airpax Sanpac 10A instant trip breakers cost $48.  Connectors and switches will add several more dollars.  For the cost of a Lionel 180W Powerhouse Power Supply brick 4 150W power supplies can be built.  My layout design will require 3 or 4 TIUs and The Antek toroidal transformer helps to keep the costs down

I only see two ??

John

Carl, I appreciate your resourcefulness and desire to find a frugal solution for multiple 18VAC power sources.  I am familiar with AnTek toroidal transformers due to their use in high end audio components requiring a low noise, pure sine wave, positive and negative power supply.

I also noticed what Craftech questioned that the spec sheet for the AN-6218 has what we would call 2 output (pairs).  They may be referring to the four output wires, aka number of output taps.  Two outputs are typical in the types of applications most would use these transformers.

Also in the specs they claim: "In most of the cases, this transformer can be output 20%
more power from its rating at 60Hz power source
without any problem."

That would mean usually they can output about 10Amps.  However the 10A Instant Airpax you're considering are not guaranteed to trip until the current through them reaches 13.5Amps.  If it were me, I'd go with one 7.5A breaker per output.

Well, they mentioned only two 18V outputs, but Carl's picture has twelve wires, so it appears that it indeed has four outputs.  The spec for that transformer doesn't account for the orange and brown wires.  The real question is, where's the actual specification for that specific transformer with four outputs?

Another question.  How are the secondaries configured and how would they be wired to have a single 0 Volt reference?

It may be a good idea to call Antek to answer some of these questions before ordering.

If there are four separate windings, I can't think of a scenario where the four couldn't be used and phased properly.  However, it certainly would be useful to have the proper specification for the transformer in question as the one you find with that number isn't the right one.

Would this be the recommended way to connect the secondaries to produce 4 x 18V phased sources with a single 0V common reference?

Looks right to me Steve, and for 115VAC input, the two primaries are in parallel.

Remember that the phasing of the four secondaries have to be checked, without knowing what the color code is, you'd just have to do a small science project to figure out the phasing.

Sorry for the delay in responding.  I wanted to use my oscilloscope to check the phases.  In my test track I used the Antek AS-3218-300VA 18V transformer which is a 2x output transformer.  The diagram GRJ posted is correct for that transformer.  I made the blue outputs the common.

I measured the 2 output waveforms.  CH1 is slightly offset to be visible.

After working with the $50 Antek AS-3218-300VA 18V transformer I will probably use this transformer instead of the 4x Antek An-6218-600VA 18V.  The cost per output will go up about $4 but at 7 lbs it will be much easier to work with than the 12lbs Antek An-6218-600VA.  I will take Steve's recomondation and ust the Airpac 7.5A breaker.  I will build a panel for each TIU with the transformer and all the 120V AC behind the panel and in circuit boxes.  The Antek AS-3218-300VA 18V transformer in my electronics test track worked well.  Only 2-3 minor parts of the design were not tested.  Test Track Post - https://ogrforum.com/...tive-of-the-engineer

Looks good, probably a very good transformer for the task.

My one remaining suggestion would be to go for the belt & suspenders approach and also put a 5A breaker in the primary.   Use a standard thermal circuit breaker, we're just going to transformer protection here, we don't need a super quick response.

Interesting project with multiple secondary outputs from a single transformer.  Deja Vu for me.

In the pre-Z4000 days, I built power supplies using Hammond "filament" 18v 20A transformers.  Enclosures were a challenge but I found metal boxes of sufficient dimensions at the big box home store.  The power supplies were assembled with some effort and cost with drilling, wiring, breakers, and adding analog meters in a separate enclosure.  These are beasts and I've run one with a TPC-400 at up to 20A at shows with three Pullmore-powered trains on a loop.   The TPC thermal breaker allowed significant overcurrent and spot welding before it tripped, so I went with 10A Airpax instant trips and a limit of two trains per loop.  I use a variable voltage transformer upstream of the Hammond to trim the max output to 18V.

WRT Airpax instant trip breakers, damage done by a short is amps * duration of the overload - typically manifested by the heat and burning of components.  A dead short will quickly spike amps beyond 13A and the breaker trips immediately.  To test the  breakers holding at 10A, I rigged up a resistance load (heater coils) for testing and could not go much above 10A constant current without tripping (about 10.2A max IIRC).

If you plan on running multiple trains on a power district, 7.5A may not be enough.

A Polyfuse application sheet recommended paralleling the fuses if the required amperage is beyond the largest Polyfuse available:  "The most sensitive fuse will trip first and the second immediately after".  This seemed like an approach to having dual aperage protection - run at 7.5A and if the breaker trips running multiple trains, try 15A by paralleling two 7.5A breakers.   I tried this with two 7.5A Airpax push/pull instant trip breakers.  My resistance load test could not get much beyond 10A with both breakers paralleled.  Why the paralleled breakers could not handle up to 15A is mystery that I didn't resolve.

My Airpax 10A breakers trip before a Z4000 senses an overload.

Powerhouses are an UL-approved solution and is my recommendation these days. So much simpler than building the supply and testing power protection.

It looks like they sell cases for their power supplies albeit a bit pricey.

JOhn

@Tracker John posted:

I tried this with two 7.5A Airpax push/pull instant trip breakers.  My resistance load test could not get much beyond 10A with both breakers paralleled.  Why the paralleled breakers could not handle up to 15A is mystery that I didn't resolve.

Not a big mystery, even a very slight imbalance in impedance through the individual current path to each breaker makes a big difference with high currents.  A slight impedance imbalance will put a greater load on one breaker and it will trip first, then of course the other one can't sustain the combined load and will also trip.  I've observed the same issue with people trying to parallel the Lionel PH180 bricks.

Hi Carl,

How did this project turn out?

Thanks,

John

I have built one and it works great.

Carl

@carl552 posted:

I have built one and it works great.

Carl

Hi Carl.

I am interested in building one.  Did you use the $42 housing or some other method to mount it?

If you could post a photo that would be truly appreciated.

Thanks,

John

I built the power supply and electronics board shown in the figure using the ANTEC transformer.

The front of the board is shown in this picture.  It is not going to win any industrial design awards.

c

Not all the cables or wall warts have been installed.  The only TMCC to DCS electronics is not shown and is on my test track

The back of the board is shown in this picture.

John, I have not enclosed the transformers.  I have designed enclosures that can be 3D printed for a low cost.

Carl

Where's the pictures of the actual transformer, that's the topic of the thread?

Carl,

I agree with John.  We would like to see what you did with the transformers.  If you haven't printed the 3D enclosures, can you show us the design?

Thanks,

John

I corrected the back view picture.  It shows the transformers and how they are imbedded in the electronics.  There is an on/off switch for each transformer, an on/off switch and airpax instant trip circuit breaker for each TIU input.

OK, that makes more sense.   I'd suggest labels for all the switches.

@carl552 posted:

I corrected the back view picture.  It shows the transformers and how they are imbedded in the electronics.  There is an on/off switch for each transformer, an on/off switch and airpax instant trip circuit breaker for each TIU input.

OK.  Nice project Carl

John