Need some advice on wiring these blocks

[Frank53]

The diagram below is a chopped down version of the top level of my layout.

The two lines each converge at reversing loops at each end. I want to set this up as four blocks - one for the uppermost level, one for teh lower level, and one block for each reversing loop. I also want the loops to run with minimal intervention by utilizing teh non-derailing feature.

At point "1", I will insert three fibre pins, isolating the lower switch and the track on the looop. This will run on it's own power.

Likewise, at point "4"

By placing three fibre pins at point "2", I have eliminated the power source of the lower track from teh switches on the left, which retaining the non derailing feature (I think). All track to teh right of "2" is receiving the siding power, which continues on and powers the o-72 switch all the way to the right, up to point"4".

I may not have explained this well, But I am hoping someone can decipher this determine if this will accomplish what I want to do.

thanks in advance

[Blueberryhill RR]

Frank,

I have a similar loop like yours. I supplied power, separately to each reversing loop and power to the main line. The switches both work on non-derailing feature, if using the aux. power plugs. It works great. As long as you have the fiber pins in each of the other two tracks, in the proper rail, on each switch, it will work fine. I hope that sounded ok.

I just thought of this.....I only used fiber pins in the center rail on each block. This kept the grounds open. I also grounded the center post of each switch, to the outer rails of the track. I found by doing this, that the switch would snap, just as quickly, using less volts. This may work for you, too.

[lionelsoni]

It's dangerous, as I have often explained.

[Frank53]

It's dangerous, as I have often explained.

Bob - Is there something I should know?

[lionelsoni]

Yes.  Running across the gap between blocks powered by different transformer outputs causes fault currents through the pickups of locomotives and lighted cars that can be dangerous, unless the block voltages are exactly the same voltage, phase, and waveform, which is rarely the case.  If you are using a multiple-output transformer, like a Z or ZW, with a single circuit breaker, the circuit breaker provides no protection.  Even with separate overcurrent protection for the blocks, there will be arcing and inductive voltage spikes which may harm modern locomotives.

This sort of operation is unfortunately pretty common and even suggested by Lionel, although the service manual for one of their transformers does warn of the danger in fine print.

[Frank53]

Bob:

Thanks for the input. I had planned to do this with a post war ZW. Can you tell me a better alternative?

[lionelsoni]

Frank, there are two ways to go, depending on how you plan to operate the layout.  The usual way to handle it is to use an electrical switch to connect each block's center rail to one or another of the transformer outputs, so that the same output can power the same train from block to block.

However, your layout and your description of it make me think that you are planning on more of a hands-off operation and using the transformer controls to adjust the speed, perhaps according to grade, on various parts of the layout, with the trains running over the same track.  You can do this safely in much the same way you were planning with the multiple transformer outputs by using just a single output of your ZW connected to each block through a rheostat.  Old Lionel rheostats are easy to find, on E-bay for example, and allow you to make the adjustments you might need on a block-by-block basis.  But their outputs can be shorted together at the gaps with absolute safety.  I use a couple of them for my around-the-walls-close-to-the-ceiling loop.

There is also a way to do it with strings of rectifier diodes.  These have the advantage that the voltage doesn't vary with the load that the train puts on them.  But you would need something like a rotary switch for each block to be able to make voltage adjustments without rewiring.

[A&Y Ry]

 Frank

For one thing, put some fast-acting cartridge fuses inline on each pw ZW output. I use old Autolite cartridge fuse blocks and 7-10 amp fast-acting fuses from Radio Shack. There are also iindividual inline fuseholders you can buy.

Over 30 years I have never had a problem or damaged an engine including those with new electronic innards on crossing gapped crossovers. However, there is always a first time and to be safe you can use a toggle to switch power for both districts over to only one throttle while crossing the gap and then toggle back to normal.

(Fuses or breakers are basically for protection of the power source rather than the engine. A surge or spike caused by any event will not likely be interrupted by a tripped breaker or blown fuse before it does its damage to the solder traces on the circuit boards or to the ultra small motor wires.)  

[cheech]

No expert here, but..

consider the Lionel BPC and TPC to alleviate the concerns that bob raises. The tpc will manage the voltage consistent across all blocks. it might be pricey, but if you ever intend on tmcc or have it for other loops......

1 bpc can control up to four blocks....which is what you have;  tpc allows you to run conventional using a PW ZW....so you can still throttle with the zw handles.

To operate you will need TMCC command base eqpmt to program settings on the bpc and tmcc.

 ralph

[lionelsoni]

But he can already set the voltage the same on all blocks just by wiring them together to one ZW control.  I think the point is that he wants them to be different from each other, which is a little more difficult to do safely.

[Frank53]

Thanks for the responses. This is so far over my head, it might as well be Chinese. Gotta rethink this one.

[A&Y Ry]

Bob

Perhaps it was misplaced but my concern [on my layouts] was always a differential amperage load in crossing power districts. A dual motored diesel lash up with 8 lighted cars crossing into a district running a single motored steamer pulling 15 cars and a lighted caboose.

It seemed to me that maintaining close to the same voltage level for crossing was just a matter of adjusting the the different throttles for the districts [blocks] and watching the Vac meters for equality.  Anyway I have been lucky to avoid the problems you depict.

[lionelsoni]

If you're careful, you can get away with it.  But this case is especially problematic since his intention in using different controls on the different blocks seems to be to allow the voltages to be different for different grades.  Thus when it is working as intended, there is certain to be a voltage difference across the gap.

If the train keeps moving across the gap, the fault current doesn't flow for very long, and the transformer heating may not be very great at all.  But, if something happens to stall a train across a gap--perhaps very different voltages set accidentally--damaging currents will flow.  Separate pickups wired together, as on a lighted car or on separate trucks of a Diesel are vulnerable, since the fault current will flow through the small-gauge internal wiring.  But, even if the connection across the gap is robust, the transformer can be damaged, since there is no overcurrent protection with a postwar ZW.  I have mentioned before that I have on hand a couple of type-Z transformers that were certainly burned in just this way.

Of course, everyone is free to operate as he wants to.  But I do feel an obligation to point out the risks so that those who want to will know how to reduce them.