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sportav8r(at)gmail.com
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 Posted: Sat Feb 17, 2007 6:44 pm Post subject: schematic revision |
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Several listers had requested and received a copy of my power
distribution diagram a few weeks ago. To those many individuals, I
address this update.
Bench testing of the original design has exposed a flaw in the way the
Perihelion OV module is wired in. The module cannot tolerate over 18
volts on any of its terminals for more than a few milliseconds. Not
very robust-sounding for a module designed to trip at 16.2 volts, and
an expensive lesson to learn the hard way, but in the end, I think
this piece of hardware can be adapted successfully to this
application. The attached .xls file shows the revised connections for
the OV module, and I believe it lays out the bus architecture in a
more easily understood fashion. If you have an externally regulated
alternator on your plane, this scheme is of no concern to you and not
worth your time to study. If you have an IR alternator and no
external OV protection you are happy with, and need redundant power
for an all-electric ship, you might want to give it a look. This is
what I am going with, until Bob releases his IR alternator tamer, and
maybe even after 
Open in Microsoft Excel.
Comments welcome.
-Bill Boyd
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aeroelectric_schematic_for_pub.xls |
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Eric M. Jones
Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts
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| Posted: Sun Feb 18, 2007 10:33 am Post subject: Re: schematic revision (L-OVM Specs) |
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| Quote: | ...Bench testing of the original design has exposed a flaw in the way the Perihelion OV module is wired in. The module cannot tolerate over 18 volts on any of its terminals for more than a few milliseconds. Not
very robust-sounding for a module designed to trip at 16.2 volts, and
an expensive lesson to learn the hard way, but in the end,... |
Bill, and all my fine customers, et al. To clarify--The Perihelion Design L-OVM is designed to shut down voltages over 16.2V that exist for 200 mS or more. This is usually used in combination with the WhackJack-18 that clamps load dump voltages over about 18V and will do it for over for more than 500 mS.
Of course one might think, "Gee..it's made to shut off the power at 16.2V but BLOWS UP at 18V??" This is not quite what happens. The recent Maxwell Power OVM comparison (attached) also seems to have this point confused. (Although, thanks to their table I am considering raising my price substantially! BTW--The L-OVM also cuts the B leads with an external contactor.)
The L-OVM is rated 18V because it has 20V Zener clamps. The module will pass DO-160 20/40/300V transients, automotive 60V transient requirements and will even help a bit in a lightning strike--but it is not made to withstand more than 18V continuously. This is not a design weakness, it is exactly what the device was designed to do. Generally, any device with transient voltage suppression will be very unhappy if these same transient voltages are applied continuously.
I can design and build the L-OVM for any voltage, but it turns out that the Mosfets get bigger and more expensive in a hurry for the same performance, and the packaging issues abound.
Description of Operation for the L-OVM is attached.
Hope this clears up some things.
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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| Description: |
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LOVM Description of Operation.pdf |
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| Description: |
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Monitor overview.pdf |
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33.66 KB |
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172 Time(s) |
_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net |
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sportav8r(at)gmail.com
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| Posted: Sun Feb 18, 2007 11:21 am Post subject: schematic revision |
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My OVM's destruction resulted form not applying it the way Eric said
to (well, his schematic is not very similar to mine, but shows the way
Bob used to recommend controlling an I-VR alternator with a B-lead
contactor (but using MOSFET circuit interruption rather than crowbar
breaker-popping approach.) I should have been able to read between
the lines and deduce that, even in my different circuit topology, the
connections of the OVM to the circuit should all have been made on the
cold side of the OV event. It does say in the spec sheet that 18
volts is the maximum input voltage.
Eric, despite my mea culpa above, I note the absence of any reference
to WhackJacks or other suppression at the 18 volt level in the
application notes included with the OV module I purchased from you.
If it's that important, you might consider revising the documents.
Thanks for your time on the phone the other evening.
-Bill B
On 2/18/07, Eric M. Jones <emjones(at)charter.net> wrote:
| Quote: |
> ...Bench testing of the original design has exposed a flaw in the way the Perihelion OV module is wired in. The module cannot tolerate over 18 volts on any of its terminals for more than a few milliseconds. Not
> very robust-sounding for a module designed to trip at 16.2 volts, and
> an expensive lesson to learn the hard way, but in the end,...
Bill, and all my fine customers, et al. To clarify--The Perihelion Design L-OVM is designed to shut down voltages over 16.2V that exist for 200 mS or more. This is usually used in combination with the WhackJack-18 that clamps load dump voltages over about 18V and will do it for over for more than 500 mS.
Of course one might think, "Gee..it's made to shut off the power at 16.2V but BLOWS UP at 18V??" This is not quite what happens. The recent Maxwell Power OVM comparison (attached) also seems to have this point confused. (Although, thanks to their table I am considering raising my price substantially! BTW--The L-OVM also cuts the B leads with an external contactor.)
The L-OVM is rated 18V because it has 20V Zener clamps. The module will pass DO-160 20/40/300V transients, automotive 60V transient requirements and will even help a bit in a lightning strike--but it is not made to withstand more than 18V continuously. This is not a design weakness, it is exactly what the device was designed to do. Generally, any device with transient voltage suppression will be very unhappy if these same transient voltages are applied continuously.
I can design and build the L-OVM for any voltage, but it turns out that the Mosfets get bigger and more expensive in a hurry for the same performance, and the packaging issues abound.
Description of Operation for the L-OVM is attached.
Hope this clears up some things.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=95856#95856
Attachments:
http://forums.matronics.com//files/lovm_description_of_operation_865.pdf
http://forums.matronics.com//files/monitorandnbspoverview_782.pdf
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