Standby Power

[Xiropillo]

Hello there, 

Correct me if I am wrong.

When aircraft has no GPU or battery power and standby gauge is moved to BAT position, shouldn't it give power to the aircraft but only the same that battery would give for basic instruments?

In IXEG, when is moved to BAT, it gives the same power than GPU and this is not correct (if I am not wrong)

In the case that I am right, could it be fixed? 

I have been checking the behavior of this switch in FlyJSim 732, Zibo, PMDG and this one and only the last one seems to do it correct. 

Again, sorry if I am not correct.

Regards and happy new year everyone.

[Litjan]

Hi Xiropillo,

I can not confirm on my end what you are seeing - but we used to have a bug in the standby power distribution when the aircraft was on the ground, if I remember correctly. Tom has fixed that, but I am not sure if it went into the last patch...

When you are on the ground, switching on the BAT switch should power the Battery bus (the hot battery bus is always powered). When you move the STBY PWR switch to BAT then the standby buses get powered (both AC and DC) - and you will additionally gain the standby instruments (like CPTS altimeter, airspeed, and EFIS displays).

You should not get power on the generator buses - this is easily confirmed by trying to turn on the ELEC HYD pumps, for example. They only work when the GEN buses are powered.

This is the behaviour with my version - but again - maybe the latest release version did not have that fix yet.

Cheers, Jan

 

Edited December 29, 2019 by Litjan

[Xiropillo]

Thanks for your answer Jan.

I don’t understand about systems but just comparing with other 737 addons and although not all the systems get power, what I noticed was the sound of systems that comes with standby power in bat position that are the same coming with GPU. 
For example in 732 and 738 some lights come up and a sound of fans maybe but not that loud noise. Maybe gyro? Just guessing.

 

[Litjan]

The sound that you are hearing is most likely the standby altimeter vibrator and the gyro of the standby horizon?

Cheers, Jan

[Xiropillo]

And is activated with only standby battery? That don’t happen in the others. 
I know that are different models and years.

[Litjan]

The standby horizon is on the Battery bus - but the standby altimeter and the standby airspeed indicator are on the standby 28V DC bus.

I remember hearing the "woodpecker" (standby altimeter vibrator) come on in the morning when we did the standby power test (this test was removed from the normal cockpit preparation procedures sometimes in the late 90s).

The standby power in some models (newer ones) will also be on on the ground - you don´t need to move the standby power swicht to BAT to enable it. In the older models it switches off when on the ground to avoid draining the battery too fast if the pilots forget to turn of the BAT switch after leaving the aircraft. So in those newer aircraft the standby power buses are always powered when the BAT switch is on and the GEN buses loose power.

I think what we don´t have quite correct is that you can also hear some "airflow" or "cooling fan" noise when the standby altimeter vibrator comes on. This is a problem with the sound file...I recorded it in the real 737 when the aircraft was powered normally - so you can hear that equipment cooling fan sound in the background. In the real aircraft you would only hear the vibrator sound.

Cheers, Jan

[Xiropillo]

8 hours ago, Litjan said:

The standby horizon is on the Battery bus - but the standby altimeter and the standby airspeed indicator are on the standby 28V DC bus.

I remember hearing the "woodpecker" (standby altimeter vibrator) come on in the morning when we did the standby power test (this test was removed from the normal cockpit preparation procedures sometimes in the late 90s).

The standby power in some models (newer ones) will also be on on the ground - you don´t need to move the standby power swicht to BAT to enable it. In the older models it switches off when on the ground to avoid draining the battery too fast if the pilots forget to turn of the BAT switch after leaving the aircraft. So in those newer aircraft the standby power buses are always powered when the BAT switch is on and the GEN buses loose power.

I think what we don´t have quite correct is that you can also hear some "airflow" or "cooling fan" noise when the standby altimeter vibrator comes on. This is a problem with the sound file...I recorded it in the real 737 when the aircraft was powered normally - so you can hear that equipment cooling fan sound in the background. In the real aircraft you would only hear the vibrator sound.

Cheers, Jan

Many thanks Jan. Great explanation. 

Do you think it could be fixed?

Regards and happy new year!

[Litjan]

55 minutes ago, Xiropillo said:

Many thanks Jan. Great explanation. 

Do you think it could be fixed?

Regards and happy new year!

I would have to try and grab the sound somewhere without infringing copyrights - so I can´t just leech it off some other program. Let me see what we can come up with...

Cheers and happy new year!

Jan