I am a Compact user but can give some guidance on the "What would be the limit with the one TR150 transformer?"
For your planning purposes you should assume that each loco when running will need 1/2 amp. N guage might be less as this is my figure for OO. If you also have locos standing on powered sections then they will also take a very small amount of power. So in that a TR150 provides 5 amps, you will probably be limited to about 9 running locos with others idle around the layout.
If you are also planning to control signals and points via Lenz LS100/LS110/LS150 then they too require some power thus reducing the number of locos that can be run at once. If you add LR101 feedback modules for block detection then again they use a small amout of power.
I would say that running 4 at any one time is well within the capabilities of your system.
However if you start to get towards the 9-10 mark you may want to split your layout into 2 power sections. Possibly 1 section for fiddle and 1 for main scenic area. For this you will need another transformer, either an TR100 ( 3 amps ) or a TR150 ( 5 amps ) plus a booster station. Too little power and your DCC master box will keep tripping out and everything will stop dead!
With the above the 2 sections draw power from their own transformer but the command station and the booster are linked via XpressNet to provide the DCC control for the whole layout. SO even if one power section trips out ( short circuit or too big a demand ) then the other section will continue to function.
I don't think you will need to think about splitting unless you are going to run more than 9 locos and have an exhibition layout.
Hope the above helps and I am sure other forum members will correct any errors I have made.
PS sites like the following are a good source of info. Electric nose and Mackay Models
For your planning purposes you should assume that each loco when running will need 1/2 amp. N guage might be less as this is my figure for OO. If you also have locos standing on powered sections then they will also take a very small amount of power. So in that a TR150 provides 5 amps, you will probably be limited to about 9 running locos with others idle around the layout.
If you are also planning to control signals and points via Lenz LS100/LS110/LS150 then they too require some power thus reducing the number of locos that can be run at once. If you add LR101 feedback modules for block detection then again they use a small amout of power.
I would say that running 4 at any one time is well within the capabilities of your system.
However if you start to get towards the 9-10 mark you may want to split your layout into 2 power sections. Possibly 1 section for fiddle and 1 for main scenic area. For this you will need another transformer, either an TR100 ( 3 amps ) or a TR150 ( 5 amps ) plus a booster station. Too little power and your DCC master box will keep tripping out and everything will stop dead!
With the above the 2 sections draw power from their own transformer but the command station and the booster are linked via XpressNet to provide the DCC control for the whole layout. SO even if one power section trips out ( short circuit or too big a demand ) then the other section will continue to function.
I don't think you will need to think about splitting unless you are going to run more than 9 locos and have an exhibition layout.
Hope the above helps and I am sure other forum members will correct any errors I have made.
PS sites like the following are a good source of info. Electric nose and Mackay Models