---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 10/21/18: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 10:39 AM - Stuck starter questions (Pat Little) 2. 11:59 AM - Re: Stuck starter questions (Alec Myers) 3. 08:02 PM - Alternator OV disconnect (Pat Little) ________________________________ Message 1 _____________________________________ Time: 10:39:52 AM PST US From: Pat Little Subject: AeroElectric-List: Stuck starter questions Many of the Z diagrams show the starter current passing thru the master contactor as well as the starter contactor, and I gather this is to allow for the possibility of the starter contactor welding itself shut. If that were to occur then the pilot can disengage the starter motor by turning the master switch off (having a "starter engaged" light and an e-bus alt feed would both be useful for this scenario). However, I see that Z-20 shows the starter current direct from the battery to the starter contactor and not thru the master. Z-20 is for a Jabiru system, and I have a Jabiru engine so I figure (no pun intended) that I could use the Z-20 arrangement, although I don't know why Jabirus would be different in this respect. So, here are my questions: How unlikely is a welded contactor? How well does the diode prevent this from happening? Is there a way to tell if the diode has failed open-circuit? Pat ________________________________ Message 2 _____________________________________ Time: 11:59:39 AM PST US From: Alec Myers Subject: Re: AeroElectric-List: Stuck starter questions Can=99t speak for how common this is overall, but I=99ve had a s tuck starter solenoid on both my TC aircraft. On Oct 21, 2018, at 13:38, Pat Little wrote: Many of the Z diagrams show the starter current passing thru the master cont actor as well as the starter contactor, and I gather this is to allow for th e possibility of the starter contactor welding itself shut. If that were to o ccur then the pilot can disengage the starter motor by turning the master sw itch off (having a "starter engaged" light and an e-bus alt feed would both b e useful for this scenario). However, I see that Z-20 shows the starter current direct from the battery t o the starter contactor and not thru the master. Z-20 is for a Jabiru system , and I have a Jabiru engine so I figure (no pun intended) that I could use t he Z-20 arrangement, although I don't know why Jabirus would be different in this respect. So, here are my questions: How unlikely is a welded contactor? How well does the diode prevent this from happening? Is there a way to tell if the diode h as failed open-circuit? Pat ________________________________ Message 3 _____________________________________ Time: 08:02:52 PM PST US From: Pat Little Subject: AeroElectric-List: Alternator OV disconnect In the (British) Light Aircraft Association=99s technical leaflet on electrical systems it says it=99s better to disconnect a permanent-ma gnet alternator by interrupting the AC going into the regulator than the DC output from the regulator. The Z diagrams that include PM alternators seem to show the OV relay downstream of the regulator. Any thoughts on this? Pat ------------------------------------------------------------------------------------- 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.