Z4000 for more power?

If you have a 10-amp fuse at both the A and D terminals, and you have the handles at different voltages, and a car or loco jumps the gap, if you have 10 amps flowing through the loco roller set (which is possible), one or both fuses will blow.  (Actually, 10 is a bit high for a ZW; 7.5 probably a better choice.

One presumes you aren't connecting them right at the transformer, we're talking about them getting connected together somewhere downstream.  If you're going to start running scenarios like that, what happens if you connect 110V to the track?

 

Adjacent blocks are connected to A and D. A dual rollered engine stalls, sits bridging the 2 blocks. Current goes through a breaker from A in series with the roller wire and through breaker D. Will one of these breakers trip? I dont know I am asking. Id they dont it is bad on the secondary winding of the ZW.

 

Dale H

Since the windings are rated to carry more current than the breakers or fuses you should be using in this scenario, for what reason would the breakers or fuses not go?  If a breaker fails to trip at or over it's rated current, pretty much all the circuit protection bets are off, no?

 

 

Dale, on a postwar ZW, the thermal breaker was on the U terminal only.  In the situation you have described, if the voltage difference is great enough, higher-than-normal amperage will flow from A, through its external fuse/breaker, thru the track, through the rollers on the loco or the internal wiring of a car (usually real thin), through the next track block, through the D breaker/fuse, to D, through the secondary winding between there the finger for D and the finger for A are sitting.  If the rating of either fuse/breaker is exceeded, either or both will blow.

 

Note that a weak link is internal car wiring, often #22 or #24 gauge.  I have had that melt.

I postulate it might carry under 10 amps but be going through a short section of the winding in the secondary. Perhaps this would overheat a short section,I dont know,just asking.

Not a repairman and never had a ZW apart. That being said I think it is entirely possible one tap comes off a ZW and then splits with one wire going to throttle A and another wire going to throttle B.

 

I also think if you set A at 15 volts and B at 10 volts and connected 1 wire to rail common and the other to rail hot you will get 5 volts. Reverse the wires and you will get the same voltage with the phase reversed.

 

The OP poster may be able to run just fine on 1 Z-4000 throttle incandescent bulbs and all. The guy with 3 mile of track and E8 with 11 cars each should be blocking his track and using 2 TIU channels.

 

Would not a Diode between the pickup roller and light bulb stop voltage from being bridged between trucks. I know there is circuitry at the track that will prevent bridging. Years ago it was on a website and called power passing.

I can't imagine why the current through a short section of the secondary would be worse than the whole secondary.  I would think the reverse would be true, as there is greater resistance through the whole secondary, and thus more heat generated.  True, the heat is in a smaller area, but remember, I*R.

The power passing is done with a relay. An insulated outside rail at the bridge power track. The lead truck triggers the relay and cuts power to a short section of track where the trailing truck is located thus no bridging. Taking it one step further you can alternate power to the section of track the trailing truck is on between throttle A and B.

 

Wiper to center rail where trailing truck is on. N/C to trailing power side. N/O to forward power side.

 

This would be directional. With a little thought sure it could be done in both directions.

GRJ:  As you know, heat and temperature are 2 different things.  If I apply 1000 calories of heat to a one pound block of iron, its temperature will be raised much more than if I applied 1000 calories to a 100-pound block of iron. 

 

If I pump 15 amps through only 10 turns of a secondary, it will generate much less heat (calories or BTUs) than 10 amps pumped through 100 turns.  So the transformer itself won't heat as much, but the temperature of the 10 turns carrying the 15 amps will be higher than the remaining 90 which are carrying fewer amps.

 

Say I have a short between A & D, so 15 amps is flowing through those 10 turns: the temperature of those 10 turns can approach the danger point, even though the transformer as a whole may remain cool.

 

If my words can be read to state that fixed current has more of an effect on a few turns than the entire secondary, I did not choose my words well enough. 

 

F&G:  not so.  The handles for A,B,C, & D each control a finger with a roller on the end, that rolls across the single secondary, tapping off a number of turns that depends on how far the lever is moved.  ALl the way to the end away from U gives 20 volts; they only go close enough to U to give 6 volts minimum.All 4 fingers have the same length of travel over the same number of turns.  The 4 U terminals are connected to one end of the secondary, through a thermal bimetallic strip circuit breaker. 

 

One can prevent bridging in a car by placing a diode between each roller and the first bulb in line, both having the anode or the cathode connected similarly to the roller, but the bulbs will be dimmer by only getting 1/2 the wave.  You are correct that in bridging, the "shorting" voltage is equal to the difference of the transformer settings.

 

I question the practicality of your second posting, without further refinement.  As a loco comes across the gap, its lead truck will trigger the relay, but the rollers will not have reached the gap yet.  In DCS, this wouldn't be a problem, since the system isn't affected by brief power cutoffs.  But conventional locos could have reverse triggered, and if going really slow, loco could stall.  

Dimmer bulbs may be a good thing when running in command mode. To be brighter can you run a lower voltage bulb?

RJR, we're talking about limiting the current to 10 amps with our circuit breaker or fuses.  Since the windings are easily able to handle that, I can't see that having the current for only a small number of windings is any worse then having it for the whole transformer secondary, and I can make the case that it would be less of a problem.

 

I think you forgot that with the second scenario there would be the same amount of current flowing through those windings anyway, it's just that the total heat generated with a full secondary carrying the current would be much more.  That can't be better than having only a few windings carrying the same current and generating much less heat.  Those 10 turns won't get any hotter than they would with the whole secondary involved, and in point of fact, would probably not be as hot, since you have a larger mass that is cooler to help dissipate the heat.

 

I think we're spinning our wheels here, if that logic doesn't convince you, we'll just have to agree to disagree on this point.

 

GRJ:  Let's walk the cat back.  I never said pumping 10 amps through a short section of secondary windings is worse than running it through the entire length.  Where do you read me saying that?   All I said was that you don't want to have more than 10 amps flowing in the length of secondary between any 2 of the ZW's fingers, and I think you agree on that.

 

It's a mind bender to try to mentally trace the current flow in scenario #2.

 

F&G "Dimmer bulbs may be a good thing when running in command mode. To be brighter can you run a lower voltage bulb?"  Command moda does make some bulbs run too hot; I switched to LEDs for that reason.

 

 

I'm not sure what you were getting at with this statement, perhaps I am reading something you didn't intend.

If I pump 15 amps through only 10 turns of a secondary, it will generate much less heat (calories or BTUs) than 10 amps pumped through 100 turns.  So the transformer itself won't heat as much, but the temperature of the 10 turns carrying the 15 amps will be higher than the remaining 90 which are carrying fewer amps.

In any case, where I started with all of this was disputing that protecting each leg of the transformer outputs wasn't protecting the transformer from excessive currents.

I agree it doesn't read right.

 

We agree on your initial statement that all legs should be protected.  I never said otherwise.