Standby Power Test - AC Frequency

[cosmic_3000]

Hey all,

During the standby power test, AC frequency is below scale when Standby Power switch is set to AUTO, but 400Hz when set to BAT. This is with aircraft on APU power.

Is this normal operation, or something wrong?

Ty!

[Litjan]

It looks like the standby power switch in your second shot is on OFF. This would turn the Stanby Power off, with no frequency being generated by the inverter. Move it to STBY (full left) to activate the standby power.

If the switch is on AUTO (as it is normally), you would not get standby power while the plane is on the ground - it would only activate in the air (safety feature to avoid draining the battery on the ground)

Cheers, Jan

 

[Tom Stian]

2 hours ago, Litjan said:

you would not get standby power while the plane is on the ground - it would only activate in the air (safety feature to avoid draining the battery on the ground)

I can "confirm" that.

I recently had a "DC electronic 1" - failure. And just when I touched down I lost alot of electronics. And dident understand why. So had to check the FCOM. But found out that it was working as intended. Pretty neat

 

[mfor]

Still weird that it shows no (or too low) frequency but correct AC voltage, if it is off shouldn't both be zero?  

 

Edited September 21, 2017 by mfor

[Litjan]

3 hours ago, mfor said:

Still weird that it shows no (or too low) frequency but correct AC voltage, if it is off shouldn't both be zero?  

 

I think you are right, I remember that discussion about the pickup point of the voltmeter we had, and it is possible that we have a bug there. I still have to get out the wiring diagrams from the AMM to check...

Cheers, Jan

 

Edited September 21, 2017 by Litjan