---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 12/31/24: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:26 AM - Re: Re: OVP relay in B+ lead bad idea (Finn Lassen) ________________________________ Message 1 _____________________________________ Time: 08:26:52 AM PST US Subject: Re: AeroElectric-List: Re: OVP relay in B+ lead bad idea From: Finn Lassen Thanks Joe. I'm now thinking that the ripple spikes from the alternator (open battery) triggered the OVP module which killed power to the relay and also power to field winding and voltage regulator. Probably happened fast enough for the 5A breaker not to trip. Still hard to believe that the OVP SCR was able to pull the output small rectifier bridge in the alternator to ground (without damaging the diodes) long enough to kill the magnetic field. I bench tested the alternator with a 1/2HP drill motor and it seems to work OK. However, without battery, the ripple peaks exceed 15V+ which would cause continuous triggering of the OVP module. (appears the internal voltage regulator uses average rather than peak voltage). Moral of story is still: no B+ relay. Supply field/voltage regulator externally. Actually, do have a backup battery! Finn On 11/15/2024 12:46 PM, user9253 wrote: > > It takes a lot less voltage and current to hold a relay closed than it does to first energize it. > Just because a circuit breaker is marked "5A" doesn't necessarily mean that it will trip at exactly 5 amps. > It should be bench tested with an adjustable current power supply. It might be tripping at much less than > 5 amps. A loose connection will generate heat which can result in a breaker tripping at > less than its rated current. The alternator field circuit breaker should not be tripping. > - > Good job making a forced landing and walking away. Many pilots panic when the engine > quits and pull back on the stick to avoid going down. The wings stall with fatal results. > The ground doesn't give. Bob Hoover quote: > "If you're faced with a forced landing, fly the thing as far into the crash as possible." > > -------- > Joe Gores > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=514526#514526 > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.