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Old 11-02-2019, 07:02 PM
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gmcjetpilot gmcjetpilot is offline
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Originally Posted by dave4754 View Post
A friend here had a surge go through his Cessna Skymaster and $40K later he restored the panel to service. One needs good protection.Dave
Scary. $40K. Nice panel. What did he blow? I ask because most modern avionics runs on 10 to 30 volts and they have their own OV protection. Old school avionics were virtually unprotected... power went right in the board where the semiconductor had low voltage ratings (capacitors, transistors, diodes, IC's). Avionics have improved from the "classic" stuff.

Originally Posted by WingsOnWheels View Post
I have a crowbar OV module on my internally regulated auto alternator as well. The alternator B lead is connected to the buss via an 80amp contactor. The contactor coil is powered from the main buss using what would normally be the field breaker. The crow bar connects the breaker to ground. If a OV occurs, the crowbar trips the breaker and disconnects the alternator from the buss. The current flyback would likely kill the internal regulator, but it must have had a fault anyway to cause the OV.
That's how I did it, but my Alternator is only 40 amps and run a 50 Amp CB. The max draw of the plane night is no more than 25-30 amps (LED's are amazing). With that said I have a OV relay on the Aux bus as well to isolate the electronic ignition and run from Aux battery only.
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Last edited by gmcjetpilot : 11-02-2019 at 07:07 PM.
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