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Simple Transformer ? (Bob N. !)

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Simple Transformer ? (Bob N. !)
Posted by traindaddy1 on Saturday, July 16, 2011 8:16 AM

Without getting into the "nuts & bolts"..........Which supplies more power to the track?  The CW80 or one terminal from a ZW275.     As always, many thanks.

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Posted by jmkk on Saturday, July 16, 2011 8:23 AM

The ZW.

Jason   

 B&O  =  Best & Only

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Posted by lionelsoni on Saturday, July 16, 2011 9:08 AM

I agree.

Taking the ZW's maximum voltage to be 20 volts and the circuit-breaker's setting to be 15 amperes, you can get 300 watts from a ZW, even though Lionel rates it for only 180 watts continuously.  Whether you draw that from one terminal or several doesn't matter.

The CW-80's overcurrent protection, according to the manual, is set at 5 amperes.  So, at its maximum voltage of 18 volts, you should be able to get about 90 watts out.  Because of the non-sinusoidal waveform, these numbers are a little vague; but close to the maximum transformer voltage of 20 volts RMS, the waveform should be nearly sinusoidal.

Bob Nelson

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Posted by traindaddy1 on Saturday, July 16, 2011 11:25 AM

Jason:   Bob N. :       THANK YOU.

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Posted by gunrunnerjohn on Saturday, July 16, 2011 2:11 PM

Note that the ZW will NOT deliver anything like 300W continuously to the load, normally they top out in the 225-250 range.

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Posted by lionelsoni on Saturday, July 16, 2011 2:51 PM

That's right.  I would take Lionel at their word and stay below their number of 180 watts.

It's important to understand that postwar transformers were not designed to be foolproof.  Aside from their serious vulnerability to overcurrents between their multiple outputs, the circuit breaker protected only against overcurrent and not against putting out excessive power.  The ZW's power was limited to 180 watts by the circuit breaker only if the voltage happened to be set no higher than 12 volts!  Above that voltage, the power, as we have seen, could grow much higher.  The responsibility for keeping the continuous power below what the transformer can stand rested (and still rests) with the user.  The technology for more sophisticated protection at a toy-train price was still far in the future (although I do think they could and should have put a circuit breaker on each output circuit).

Bob Nelson

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Posted by gunrunnerjohn on Sunday, July 17, 2011 5:07 PM

One thing that always makes sense with multiple outputs is to put a fuse in each circuit, adds a little insurance.

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Posted by lionelsoni on Sunday, July 17, 2011 7:08 PM

A fuse is good.  I like thermal circuit breakers because they model the heating of your wiring, letting you safely overload the circuit for short times, without tripping or blowing.

Aside from safety, the individual outputs of large transformers can be protected at lower currents than the transformer as a whole, letting you use smaller wire than you would otherwise need.  For example, a circuit protected at 5 amperes can safely use 20 AWG, while 18 AWG is safe for 8 amperes and 16 AWG for 10 amperes.  It's unlikely that a train will draw more current than that.

 

Bob Nelson

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Simple Transformer ? (Bob N. !)
Posted by thankey on Wednesday, July 20, 2011 1:20 PM

What circuit breaker (size, brand and source) would you recommend to protect at 5amps.  I have a KW, 1033, RW, & TW if that come into play.

I see some  6A at All Electronics (one of my favorite sources) but it looks too "new school".  I'd prefer that it not only protect but have somewhat of a retro / classic look.  The others they carry are either woefully small 1-2A or too large 20A.

What do you suggest?

Thanks as always.                               Tom

 

 

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Posted by lionelsoni on Wednesday, July 20, 2011 2:58 PM

Automotive parts stores have suitable thermal breakers.  I would get the automatically resetting type.  They shouldn't cost more than a few bucks.  Sometimes ones rated at 5 amperes are harder to find.

Don't worry that the automotive breakers are rated for 12 volts DC.  The fact that we use AC easily compensates for our somewhat higher voltages.

Bob Nelson

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