CW 80 Available Current

5 amps is safe.

Even if the green light blinks only briefly when starting a train or going up a grade you will be fine.

The CW80 has a internal 8 amp fuse. It would require a dead short to pop that fuse.

Even though the transformer core itself is capable of 8-10 amps, it is electronically limited to 5 amps output, and will deliver this continuously.

The fuse is to protect the core and is packed in the primary winding, connected in series with it. Even a dead short at the output won't blow the fuse. It has been known to fail under normal operation, however, rendering the CW DEAD.

I think we are talking about two different fuses.

The one I am talking about is a 8 amp glass tube fuse on the secondary side of the transformer. I have blown this fuse and replaced it. (its not easy)

I think the one you are talking about is a thermal fuse inside the transformer core. I have never seen it myself because I have never gotten that deep into the core. But yes, when that thermal fuse pops, just throw the whole thing in the trash.

I have never experienced a problem with that fuse and have no idea what conditions will cause it to open.

I will say this...

The cooling fan in the CW80 is very important for reliable operation. If that fan dies the rest of the CW80 will eventually die also.

Even a dead short at the output won't blow the glass fuse. It too has been known to fail under normal operation, however, rendering it dead unless you disassemble it.

And you would be right with that estimate.  I've never been able to get the 5 amp continuous from the CW-80.  The four I have range from 3.5 to 4.5 before the light blinks.

I sold 21 or so of these on eBay and tested every one with an ammeter and a 2333 with a good load at full throttle. Every one pegged the meter at 5 amps solid when the light started to flash.

I just took the only CW-80 that I have, I placed a 2.66 ohm load across it (3 really large 8 ohm resistors) and it gets to 4.66 amps before the light just starts to flicker.  At full throttle, it got to 4.73 amps with the light flashing away, but it was still delivering around 14.8 volts.

I added a 4th 8 ohm resistor to provide more load, and things actually went backwards.  Now the light just starts to flicker at 4.25 amps and 11.3 volts output.  At full throttle with the 2 ohm load I can only get 4.35 amps at 11.5 volts.

With a 4 ohm load, I could only get to 15.5 volts at 3.3 amps.

So, with a sample of one, you can't really get 5 amps out of the CW-80.  However, I never did get it to shutdown, just madly indicating an overload.

Thank you all for your input.

It looks like the answer is 4 to 5 amps.

I wanted to use these for a layout I'm building for my grandsons 10 and 12.  But the fact that they never shut down in a short condition worries me.  Even though I tell them to always pull the plug when they're done playing and to always shut the power off when something goes wrong they're still kids.  Gunrunner's results are a bit disconcerting.

I think I'll go with something that has a manual reset breaker.  I think a Z100 fits the bill.

Thanks,

Mike G

The CW-80s do shut down the outputs on shorts.  I've done it a few times (Happens when a one year old is driving.).  The way they work is they start blinking to let you know that there is over current.  This gives you a chance to turn the power off yourself.  But after like 10 seconds (I don't remember the exact timing.) if you haven't fixed it, it will cut the power.  To restore power you have to either turn the handle off and wait for a bit, or unplug and re plug in the transformer.  This info is all in the CW-80 manual (Sorry, I'm feeling too lazy right now to look up the manual online.).

On a true overload, that's true.  However, they don't shutdown when the light is just blinking, I left it doing that for at least 5 minutes during my testing.