Hi. I searched on this site and found only few threads on Aeroelectric connection systems (Z-11, Z-12, Z-13 and Z-14).
I read Bob book and would like to go with a single battery, dual alternator system, to fly very light IFR and eventually upgrade later.
Apart from SD-8 and SD-20 selection (I think SD-8 would not be enough...still have to do some calculation), I saw in Bob FAQ that Z-12 is not raccomended for a new design (I guess he suggests Z-13 or Z-14). My question is: why?
I understood that Z-12 is a single layer system, but you can use at your choice main alt. (main alt. switch ON and aux. alt. switch OFF) OR aux. alt. (main alternator switch OFF and aux. alt. ON). Aux. alt. is connected to the same layer of main alt. (this is the limit...), but one can lower the current consumption simply switching off some circuits (i.e.: EFIS, which has its own battery, ecc...). And this seems a simple system. One can also design it only for one alt. and upgrade it later.
I understood that Z-13 is designed to make the aux. alt. work on endurance bus only. So, if main alt. goes out, you can simply switch the other on (I guess that if you have SB-1 instead of LR3 this is automatic). But you can also let current go from endurance bus (aux. alt. only working) to main bus switching on battery contactor. So, one may have the same functionality of system Z-12 with a difference: in Z-13 you shall not switch secondary systems off to stay within aux. alt. supply, because this is the natural design feature of this system.
Well, if this is true (and I fear I missed something), why go to the more complex Z-13 if one knows that will use an SD-20? With SD-8 I can deduce that you save 1 amp. (on total 8...not bad) without closing battery contactor. But with SD-20, why complicate your life for one poor amp. on a total of 20?
Thanks.
Camillo
I read Bob book and would like to go with a single battery, dual alternator system, to fly very light IFR and eventually upgrade later.
Apart from SD-8 and SD-20 selection (I think SD-8 would not be enough...still have to do some calculation), I saw in Bob FAQ that Z-12 is not raccomended for a new design (I guess he suggests Z-13 or Z-14). My question is: why?
I understood that Z-12 is a single layer system, but you can use at your choice main alt. (main alt. switch ON and aux. alt. switch OFF) OR aux. alt. (main alternator switch OFF and aux. alt. ON). Aux. alt. is connected to the same layer of main alt. (this is the limit...), but one can lower the current consumption simply switching off some circuits (i.e.: EFIS, which has its own battery, ecc...). And this seems a simple system. One can also design it only for one alt. and upgrade it later.
I understood that Z-13 is designed to make the aux. alt. work on endurance bus only. So, if main alt. goes out, you can simply switch the other on (I guess that if you have SB-1 instead of LR3 this is automatic). But you can also let current go from endurance bus (aux. alt. only working) to main bus switching on battery contactor. So, one may have the same functionality of system Z-12 with a difference: in Z-13 you shall not switch secondary systems off to stay within aux. alt. supply, because this is the natural design feature of this system.
Well, if this is true (and I fear I missed something), why go to the more complex Z-13 if one knows that will use an SD-20? With SD-8 I can deduce that you save 1 amp. (on total 8...not bad) without closing battery contactor. But with SD-20, why complicate your life for one poor amp. on a total of 20?
Thanks.
Camillo