What size/style circuit breaker do I need?

[fiatfan]

I'm planning to use this http://www.bakatronics.com/shop/item.aspx?itemid=581 motor control, this http://www.radioshack.com/product/index.jsp?productId=2102702&filterName=Type&filterValue=Transformers# transformer, and this http://www.radioshack.com/product/index.jsp?productId=2062583 rectifier to run a G scale engine.  The manufacturer (USA Trains) confirmed in an e-mail to me that the engine requires 2.5 amps.  The engine has two can-type motors.

I have about 145 feet of track in a single loop.  No other engines/ track accessories will be run from this circuit.  My question is what amperage and type of circuit breaker should I use and where in the circuit should I mount the breaker?  If possible, I'd rather not use a fuse.

Any information, guidance, or suggestions will be greatly appreciated.

Tom

[dwbeckett]

I would put one inline with the power feed and one inline with the track feed that's off the top of my head without looking up what u are using.

Dave

[fiatfan]

OK.  Thanks, Dave.

Tom

[kstrong]

I have a few questions. First, have you run the loco at 12 volts to see if it runs as fast to suit your tastes? Most "diesel guys" tend to operate on the higher end of the speed spectrum, and 12 volts likely ain't gonna get you there. At the same time, with only 145' of track, operating at slower speeds will make the railroad "feel" larger since it takes longer for the train to go around.

Second, does the throttle controller require a filtered DC input? Simply rectifying an AC transformer isn't going to cut it. I don't see any filtering capacitors or other things on that controller, so I'd guess it would need a filtered DC input.

Lastly, I think your choice of transformer is pretty wimpy for use in the garden. I'd get something with a bit more guts.

If it were me, quite frankly, I'd look at buying a good regulated power supply from Meanwell or similar. These can usually be found for under $50, even for a 24volt, 10-amp unit. That takes care of your filtering needs for the input to your throttle, and it will also already have circuit protection built in on the AC side of the equation. You'll only need to add a circuit breaker to the output of the throttle. I'd probably go with 5 - 7 amps on that.

Do that, and I think you'll have one dandy set-up that will give you plenty of speed and power to handle not only this railroad, but also allow you plenty of room to grow.

Later,

K

[piercedan]

instead of fuses and circuit breakers, go with a polyfuse.

The polyfuse is a thermal device and heats up to be a high resistance on over current.

When load(short) is removed, this device cools down thus acts like a self resetting circuit breaker.

LGB installs these in the reat power jack of engones for feeding trailing cars with lights/sound.

Train-li uses these on the powered switch frogs (you would not want to remove a switch on your layout to change a fuse!!).

[fiatfan]

Thanks for the tips.  The twelve volts provides adequate speed for three reason:

1.  I have a couple of small radius loops - ~7' diameter.

2.  Grandkids.

3. Great-grandkids.

Tom