---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 08/22/15: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:20 PM - Re: Anything 'unique' about incorporating EarthX? (blues750) 2. 07:26 PM - Re: Newbie with PM alternator feed question (blues750) ________________________________ Message 1 _____________________________________ Time: 07:20:02 PM PST US Subject: AeroElectric-List: Re: Anything 'unique' about incorporating EarthX? From: "blues750" [quote="nuckolls.bob(at)aeroelect"] > With a B&C overvoltage protection module (nominal trip voltage of 16.2 volts), I could have voltage to the battery greater than the BMS triiger voltage and have loss of battery power supply at the same time I have no alternator electrical source! How so? At what voltage and how fast does the BMS bring the battery back on line? What leads you to believe that during the interval from onset of an ov condition, alternator shut down and BMS recovery . . . that the bus voltage will drop too low for too long to keep the fan running? Bob . . . > [b] Bob, That's part of my dilemma, I cannot answer that question yet. Failure characteristics with respect to time onset and voltage ouptut during a failure to an overvoltage output by a generator or regulator of my type I do not know. If I am recalling correctly, I have read that the B&C OVPM reacts within milliseconds to an overvoltage issue. The Earthx BMS starts doing it's thing around 15.5 volts - but that is dependent on a few variables. I have asked the engineer for some time, temp, charge state and charging voltage correlations to try and determine how quickly the BMS will react and protect the cells and simultaneously deprive me of needed power to my busses from the battery. Again, it is my understanding after talking with the engineer at Earthx, that no voltage is available from the battery (nothing allowed in or out) while the BMS is protecting the battery I still need to followup with those questions, if they are indeed the right questions to be asking! (I think so [Rolling Eyes] ) but was trying to get more insight here first. Based on my understanding at this point, I am concerned about a scenario in which the output from the alt and R/R to my battery and busses is somehow slowly rising above 15-16 volts. The BMS decides to act out and take my batteries offline. I can fly on the alternator if necessary though maybe not ideal for some equipment or to what value the voltage may rise. But to get my batteries back, I do need to alleviate the overvoltage presented to them. Ideally, I would notice the overvoltage prior to the BMS getting protective, simply shut down the alternator and proceed to the hangar with my batteries supplying the required voltage as intended. But, having to take my alternator off-line with my batteries off-line simultaneously does not seem like proper design if that is indeed a real possibility. Appreciate the initial feedback and comments, would gladly welcome any more related to this scenario. Dave Read this topic online here: http://forums.matronics.com/viewtopic.php?p=446282#446282 ________________________________ Message 2 _____________________________________ Time: 07:26:20 PM PST US Subject: AeroElectric-List: Re: Newbie with PM alternator feed question From: "blues750" [quote="nuckolls.bob(at)aeroelect"] > > (1) Is dynamo current "self limiting" a characteristic of all 3 phase PM type alternators? (dynamos?) Would gladly eliminate those three 20 amp c/b's if not required! the PM alternators will self-destruct if presented with a hard short on their windings generated by failure of the rectifier=regulator. Use in-line fuses. One for the single phase machines, two for the three phase machines. These need no be crew- accessible. Do you mean these "need to be" or "need not be" crew accessible? Why? or why not? > (2) Was planning on a 40A ANL type fuse for the 10 ga wire from the relay to the primary bus. What is the rated output of your altenrator? An inline maxi-fuse of next-step higher value would be fine and a lot less bulky. 30 Amp alternator, and I like the idea of the inline maxi-fuse versus the ANL because of the reduced size. I thought ANL type was preferred because of the longer response time and thus helped to avoid potential nuisance trips? Bob . . . > [b] Thanks Bob! A real treat to be able to discuss topics with subject matter experts! My cluebag continues to fill... Dave Read this topic online here: http://forums.matronics.com/viewtopic.php?p=446283#446283 ------------------------------------------------------------------------------------- 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.