B737NG electrical questions

[bennierex]

I am creating a computer program that simulates some of the systems found in a 737NG. Although it's just for fun, I would like to make it as realistically as possible.
Currently, I am working on the electrical system, but I've run into some problems and hope you can help me out

1) Can the Battery Bus be powered from the battery/charger independently of the AC and DC standby buses? (i.e. when TR3 fails). And if so, will the Standby Power switch need to be in AUTO, or can this be OFF as well?

2) Can the Battery Bus be powered by TR3, while the AC and DC standby buses are powered from the battery/charger? (i.e. Txfr Bus 1 and/or DC Bus 1 de-energized, so the SPCU will switch to battery power, provided battery switch ON and standby power switch in AUTO)

3) What is the condition for the SPCU to switch to battery power? The AOM says loss of power on AC Txfr Bus 1 and/or DC Bus 1. Is this correct or are there any other conditions to cause the SPCU to switch power?

Thanks in advance,
Ben

[Cap 56]

1) Yes and Yes, has to be in auto

2) AC busses are nevr powered from bat ch, what do you mean ?

3) loss of AC standby, DC standby or Bat Bus

[bennierex]

I meant AC standby bus and DC standby bus, sorry for the confusion.