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9024 module lights, labeling

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jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Mon Aug 16, 2010 5:33 pm Post subject: 9024 module lights, labeling

Group,



I am labeling the panel that will contain the aux alternator switch and the aux alternator will most likely be controlled by a 9024. The 9024 low voltage function will power a flashing LED. As the 9024 latches open in an over voltage event (triggering the LV LED) and requires removal of power to reset, it seems that adequate notice of OV power interruption would be given by the flashing LV LED



So is there any reason to have an OV test switch, or OV indicator light?



Thanks,

John

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nuckolls.bob(at)aeroelect
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Posted: Tue Aug 17, 2010 8:23 am Post subject: 9024 module lights, labeling

At 08:33 PM 8/16/2010, you wrote:

 	  Quote: 	
		  



Group,



I am labeling the panel that will contain the aux alternator switch 

and the aux alternator will most likely be controlled by a 9024.


	


   Yes, a single 9024 configured for OV protection combined with

   a relay watches the bus voltage and latches a relay to remove

   field power on an OV condition. It must be cycled OFF/ON to

   reset.



 	  Quote: 	
		    The 9024 low voltage function will power a flashing LED. As the 

 9024 latches open in an over voltage event (triggering the LV LED) 

 and requires removal of power to reset, it seems that adequate 

 notice of OV power interruption would be given by the flashing LV LED


	


   No, when configured for LV monitoring, the LED flashes

   ONLY while the monitored voltage is less than 13 volts.

   The light goes out by itself if the voltage rises after

   an LV event.



 	  Quote: 	
		  So is there any reason to have an OV test switch, or OV indicator light?


	


   No, I've considered a press to test on the ov modules but

   they're so reliable that I've not reached the 'tipping point'

   for adding that feature. Even in the generator controllers

   for the big-guys, hitting the "test" switch emulates a lot

   of ov protection shutdown . . . but does not proof the

   system's calibration.



   I AM considering changing the relay-driven OV protection

   to use a DE-energized relay to turn the alternator off.

   Since the relay is the most vulnerable component of the

   system, it seems like a good idea to have a broken coil

   wire annunciated by failure to bring an alternator on

   line. The converse philosophy increases risks for an

   un-annunicated latent failure with no means for pre-flight

   testing.



   That's the premise unders which the quest for the elegant

   design is conducted. Minimum parts and risk while

   maximizing performance.



   If your ov system is functioning right, an OV WARN light

   will illuminate one time for a few tens of milliseconds.



   If you use a relay that is energized to shut down an

   offending system, then one COULD put an OV TRIP annunciator

   in parallel with the relay coil. That way, if you DO get

   an LV warning, you'll have additional information that

   speaks to root cause . . . but it doesn't help you much

   in flying the airplane.



   Bob . . .

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jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Tue Aug 17, 2010 6:47 pm Post subject: Re: 9024 module lights, labeling

 	  Quote: 	
		  No, when configured for LV monitoring, the LED flashes

ONLY while the monitored voltage is less than 13 volts.

The light goes out by itself if the voltage rises after

an LV event. 	




So in an OV event, power to the 9024 module (and LV LED) latches open, preventing the LV monitoring function from operating?



I would like to have some indication, besides noticing my voltmeter indication of low voltage, that my stby alt dropped out and that I was now riding on the battery alone (assuming that I was using the stby alt because my main alt dropped out) . The AFS EFIS volt meter alarm output can be wired to an LED for that purpose.



JB

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