What happens between power blocks operated by separate transformers?

RWL posted:

My layout is going to have a main loop, and an inner loop, each powered by separate transformers so that I can run two trains at the same time.

I have recently heard about engine jump at these points, so I have to ask: What does happen when a locomotive with double pickups, crosses from one block onto another, and both are powered up, and the engine half on one and half on the other?

How do you guys that have been doing this for awhile handle this situation?

Going from block to block, when powered by the same transformer seems to be no issue, but I have had no experience with separate blocks powered by separate transformers.

Thanks for any and all comments on this.

You have to make sure both sections are on the same electrical phase in relation to each other.  The easiest way to check is with a voltmeter.  Check from center rail of one block to the center rail of the other.  If it reads 0V you're fine.  If it reads 30+ volts then they are out of phase.  The poor mans way to fix it is to file the larger male plug that goes into the wall so it can be turned 180 degrees.  The other way is to physical swap the power cord leads inside the transformer.

As long as both transformers are in phase and have the throttles set to the same voltage everything should be ok when crossing between tracks.

Thanks guys,

Regarding the relays, I am only looking to switch power blocks on and off.

How much current should the toggles be able to handle, voltage, amperage, etc........

Toggles should handle 10 amps. A PH-180 is 18 volts and 180 watts which is 10 amps of current and is generally what is recommended around here. A relay would also need the 10 amp rating if you decide to use any of them. You only need to switch the center rail, not the outer rails.

rtr12 posted:

Toggles should handle 10 amps. A PH-180 is 18 volts and 180 watts which is 10 amps of current and is generally what is recommended around here. A relay would also need the 10 amp rating if you decide to use any of them. You only need to switch the center rail, not the outer rails.

Thanks for the clear rating on the toggles and relays.

I realize that I don't need to switch the commons, as that is simply the other half of the circuit.

What I wonder is if I should have more that one common connection on a larger loop with non-derailing switches involved?

Maybe you should consider adding more blocks.  Each block should be controlled by a "center off" double throw switch.  This would of course allow for turning the block off which has advantages. And the block your locomotive is in would be powered by one transformer and also the block that your locomotive is going to would be powered by the same transformer.  This is essentially what real dispatchers do when they align a route for a real locomotive.  When the locomotive leaves a block you turn it off essentially releasing the block for alignment for another locomotive to use.  This is why you would use the double throw Switches so that your second locomotive running on the second transformer could be aligned using the opposite throw.

And if you shut one block off and a locomotive with dual rollers crosses between the two blocks isn't the power going to flow through the locomotive to power that next block and might fry something? Mistakes do happen or what if one block is set to a higher voltage than the other by accident will that damage the locomotive?

E-Unit, are you street level NYCTA or Subway?  I suggest you get a good book about wiring your railroad.  There are plenty out there.  Your supply is the transformer when the block is turned on. Your load is the electric motor in the locomotive. There would be NO flow to the dead block when the front pickups cross to the dead track unless there was a locomotive sitting in the dead block and then it is conceivable that electricity would flow out the front rollers to the dead track to the locomotive sitting on the track.  But it would be momentary until the rear rollers pass to the dead track.

If you are concerned about frying something, are you running command control or just older conventional locomotives? If command control solely, why bother with blocking your Pike? It is a level of complexity and further money drain which could be used to buy other locomotives or rolling stock or scenry or etcetera.

Once you have verified that all transformers are correctly phased, and all of the blocks are powered up, you should not have any problems.  However, if one of the blocks is powered off, the locomotive or dual roller lighted car that spans the insulated section will carry the amperage to the powered off block.  If there is a short or big load (i.e. long string of postwar lighted passenger cars) on the unpowered block, wires and circuit board traces can burn up.  In my experience, lighted baggage cars are particularly susceptible (fine wires) .

Loose-Caboose posted:

Maybe you should consider adding more blocks.  Each block should be controlled by a "center off" double throw switch.  This would of course allow for turning the block off which has advantages. And the block your locomotive is in would be powered by one transformer and also the block that your locomotive is going to would be powered by the same transformer.  This is essentially what real dispatchers do when they align a route for a real locomotive.  When the locomotive leaves a block you turn it off essentially releasing the block for alignment for another locomotive to use.  This is why you would use the double throw Switches so that your second locomotive running on the second transformer could be aligned using the opposite throw.

I am not sure why you suggest the double through switches. Can you elaborate on that?

I do have my main, long outer loop cut into three blocks, so that I can park a train on the far side while I move a new train from the yard siding out into the main line.

I also have a siding, inside and  across the bottom of my smaller, inner loop, that is blocked. The bottom length of that loop, just below thos diding,  will also be blocked for moving trains around.

If you are suggesting running multiple trains on the same loop, be it known that my layout isn't big enough, nor am I a good enough train master for that kind of action.

BTW, a SCARM version of my current layout plan is posted over in the layout forum.

RWL posted:

Loose-Caboose posted:

Maybe you should consider adding more blocks.  Each block should be controlled by a "center off" double throw switch.  This would of course allow for turning the block off which has advantages. And the block your locomotive is in would be powered by one transformer and also the block that your locomotive is going to would be powered by the same transformer.  This is essentially what real dispatchers do when they align a route for a real locomotive.  When the locomotive leaves a block you turn it off essentially releasing the block for alignment for another locomotive to use.  This is why you would use the double throw Switches so that your second locomotive running on the second transformer could be aligned using the opposite throw.

I am not sure why you suggest the double through switches. Can you elaborate on that?

I do have my main, long outer loop cut into three blocks, so that I can park a train on the far side while I move a new train from the yard siding out into the main line.

I also have a siding, inside and  across the bottom of my smaller, inner loop, that is blocked. The bottom length of that loop, just below thos diding,  will also be blocked for moving trains around.

If you are suggesting running multiple trains on the same loop, be it known that my layout isn't big enough, nor am I a good enough train master for that kind of action.

BTW, a SCARM version of my current layout plan is posted over in the layout forum.

The double throw Switches would allow for the hot of either transformer to be routed to your blocks. Note the word "either", not simultaneously.  So for instance you want to run a train continuously around your outer loop, you would throw your three togle switches such that the same transformer fed all three blocks.  While your second transformer's hot would fed your inner loop.  For what ever reason you would want your second transformer to control your outer loop, you throw the switches to the other side and Wala.  Of course your first transformer togle switch would also be thrown to control the inner loop.

I haven't seen your layout yet.  However I essentially use the same process to control my layout.  I run conventional and Command Control simultaneously using the TMCC BPC's to switch transformer/TPC combinations to the appropriate blocks as need be.  Yeah sometimes I am busier than a one arm paperhanger.  But usually my sessions have a couple of guys as Engineers and conductors while a fifth is busy running switches and clearing and aligning routes.  More times than not I run full Command Control.  It's just easier.

Your plan should work fine. As the guys mentioned above for keeping the transformers in phase and the toggle switch amperage. Even with the transformers in phase you never want to park any piece of equipment spanning a block end as the internal wiring becomes a jumper even if it is only powering a caboose.

Using a center off toggle would allow you to park a train in Loop 1 that was powered by Transformer A and change everything on the route to Transformer B going into Loop 2 when you power that up. Not needed though it will prevent you from "jumping" the transformer gap along the route.

The trick is remembering to have the switches flipped so all parts of your route connected to the same transformer. Especially important when running various units conventionally as they all require different voltages. Know from experience on layouts built for kids  Nothing like suddenly seeing one take off like a rocket for a stretch!

BobbyD posted:

Your plan should work fine. As the guys mentioned above for keeping the transformers in phase and the toggle switch amperage. Even with the transformers in phase you never want to park any piece of equipment spanning a block end as the internal wiring becomes a jumper even if it is only powering a caboose.

Using a center off toggle would allow you to park a train in Loop 1 that was powered by Transformer A and change everything on the route to Transformer B going into Loop 2 when you power that up. Not needed though it will prevent you from "jumping" the transformer gap along the route.

The trick is remembering to have the switches flipped so all parts of your route connected to the same transformer. Especially important when running various units conventionally as they all require different voltages. Know from experience on layouts built for kids  Nothing like suddenly seeing one take off like a rocket for a stretch!

Thanks for that explanation. I believe I now understand.

I am pretty sure that I will only ever have one transformer A, B, or C, designated for loop A, loop B, yard C.

That said, however, it couldn't hurt to use double throw toggles. Then if I did want to add that functionality later on, I could simply wire it in.

I've not had any problems for the last 65 years, since I got a second transformer.  For last 25 years, I've been using 3.  No relays or double throw toggle switches.  Only time I can conceive of there being  a problem is if there was a short on one circuit and a passenger car straddles the gap; the fine wiring inside many cars could overheat, but not carry enough current to blow the second breaker. 

Of course, if you want to introduce needless operational complexity, then follow the advice above.

If you are running conventional, then many SPST toggle-switched blocks will enhance operational capability.

Thanks. I do want to keep it simple as simple ad is practicable.

Thanks. I do want to keep it as simple as is makes sense.

Loose-Caboose posted:

E-Unit, are you street level NYCTA or Subway?  I suggest you get a good book about wiring your railroad.  There are plenty out there.  Your supply is the transformer when the block is turned on. Your load is the electric motor in the locomotive. There would be NO flow to the dead block when the front pickups cross to the dead track unless there was a locomotive sitting in the dead block and then it is conceivable that electricity would flow out the front rollers to the dead track to the locomotive sitting on the track.  But it would be momentary until the rear rollers pass to the dead track.

If you are concerned about frying something, are you running command control or just older conventional locomotives? If command control solely, why bother with blocking your Pike? It is a level of complexity and further money drain which could be used to buy other locomotives or rolling stock or scenry or etcetera.

I am surface cmf actually. I've had 5 layouts up already all of them small 6 by 9  6 by 10 I'm getting ready to build a 24 by 13 layout and someone was saying I don't remember where I read it that to run DCs you have to have blocks every eight feet or something like that. I just don't understand why. I've run TMCC and then DCS together since they've been introduced and I've never had a problem. that block thing was just a question in my head though as I remember something like that happening many years ago when I was pulling a train on a siding but maybe I did have some lighted Passenger cars on the siding I'm not sure.