Today's Message Index:
----------------------
1. 08:17 AM - Re: Sizing a B-lead ANL (user9253)
2. 09:03 AM - Re: Sizing a B-lead ANL (Eric Page)
3. 11:16 AM - Re: Sizing a B-lead ANL (johnbright)
4. 11:35 AM - Re: Sizing a B-lead ANL (Robert L. Nuckolls, III)
5. 11:37 AM - Re: Re: Sizing a B-lead ANL (Robert L. Nuckolls, III)
6. 01:43 PM - Re: Sizing a B-lead ANL (Charlie England)
7. 07:48 PM - Re: Sizing a B-lead ANL (Robert L. Nuckolls, III)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Sizing a B-lead ANL |
https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/fuses/data-sheets/bus-ele-ds-2024-anl.pdf
The rating of the ANL current limiter should NOT exceed the alternator rating.
Alternators are self current limiting. The purpose of the fuse is to protect the
battery and electrical system from "B" lead and alternator short circuits.
The rating of the fuse should be chosen so that it will never blow while conducting
maximum alternator current output.
Your friend might consider a maxi fuse. They look like giant ATC fuses.
https://m.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/blade-fuses/littelfuse_maxi_58v_datasheet.pdf
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=506118#506118
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Sizing a B-lead ANL |
Thanks very much, Joe. I'll pass that along.
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=506119#506119
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Sizing a B-lead ANL |
I haven't been able to find a definition or history of current limiters, but, at
least in the case of ANL current limiters of the ratings we use, it seems like
they are designed so you don't have to calculate how much bigger than the load
to size them, just use one placarded for your load. Note a 60A ANL will carry
over 100A continuously.
Here's what I put on my schematic:
Littlefuse MIDI/Bussmann AMI fuses are specified on this schematic for the alternator
B leads versus legacy ANL current limiters because they are physically
smaller.
ANL current limiters with the same rating as the alternator could be used but MIDI
fuses of a higher rating are chosen. It is assumed the alternator is capable
of 120% of its rated output, this is divided first by 0.75 (nuisance blowing
factor per Littelfuse "Fuseology" document) and then by 0.95 (temperature re-rating
factor per Littelfuse MIDI data sheet, 170F firewall temperature is assumed).
Main alternator: (60 * 1.2) / (0.75 * 0.95) = 101 A, close enough to 100 to choose
a 100 A MIDI.
Vacuum pad alternator: (35 * 1.2) / (0.75 * 0.95) = 59 A, a 60 A MIDI is chosen.
Alternate for alternator B leads is FLW (fuse link wire) 6" long, 4 awg smaller
than B lead, PICO brand is common; available from 10 to 20 awg. FLW is a slightly
cleaner installation; ANLs, and especially MIDIs, open with less energy.
--------
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
https://drive.google.com/folderview?id=1u6GeZo6pmBWsKykLNVQMvu4o1VEVyP4K
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=506123#506123
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Sizing a B-lead ANL |
At 11:35 PM 2/22/2022, you wrote:
>
>I'm asking for a friend, who is installing a Verner radial engine on
>a Kitfox...
>
>In some of the Z-figures, ANL current limiters are annotated as
>"sized to alternator." In others, the annotation refers to Note 10,
>which doesn't discuss sizing. On Z-12, the alternator is labeled as
>60A, and the ANL is annotated as "ANL60."
>
>So, should the ANL rating match the alternator nameplate rating as
>closely as possible, or slightly exceed it, or is there some other
>formula? I didn't find anything specific in the text of the
>'Connection, and a search on the forum came up empty as well.
ANL devices are EXCEEDINGLY robust
http://aeroelectric.com/Mfgr_Data/Fuses_and_Current_Limiters/Bussman/ANL_Specs.pdf
An ANL60 will carry over 100A continuously.
This tells us that current limiters are designed
to mitigate HARD faults (many hundreds of Amps).
So picking an ANL equal to or even SMALLER than
the alternator is not a sketchy idea.
Alternatively, consider a fusible link (4AWG
smaller than B-lead). This will serve the same
purpose and is often less expensive and more
installer-friendly.
As the Z-figures evolve, ANL and similar
devices are going to be replaced with fusible
links.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Sizing a B-lead ANL |
At 01:16 PM 2/23/2022, you wrote:
><john_s_bright@yahoo.com>
>
>I haven't been able to find a definition or history of current
>limiters, but, at least in the case of ANL current limiters of the
>ratings we use, it seems like they are designed so you don't have to
>calculate how much bigger than the load to size them, just use one
>placarded for your load. Note a 60A ANL will carry over 100A continuously.
>
>Here's what I put on my schematic:
>
>Littlefuse MIDI/Bussmann AMI fuses are specified on this schematic
>for the alternator B leads versus legacy ANL current limiters
>because they are physically smaller.
>
>ANL current limiters with the same rating as the alternator could be
>used but MIDI fuses of a higher rating are chosen. It is assumed the
>alternator is capable of 120% of its rated output, this is divided
>first by 0.75 (nuisance blowing factor per Littelfuse "Fuseology"
>document) and then by 0.95 (temperature re-rating factor per
>Littelfuse MIDI data sheet, 170F firewall temperature is assumed).
>
>Main alternator: (60 * 1.2) / (0.75 * 0.95) = 101 A, close enough to
>100 to choose a 100 A MIDI.
>
>Vacuum pad alternator: (35 * 1.2) / (0.75 * 0.95) = 59 A, a 60 A
>MIDI is chosen.
>
>Alternate for alternator B leads is FLW (fuse link wire) 6" long, 4
>awg smaller than B lead, PICO brand is common; available from 10 to
>20 awg. FLW is a slightly cleaner installation; ANLs, and especially
>MIDIs, open with less energy.
Exactly. But life is much simpler with fusible links.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Sizing a B-lead ANL |
snipped
>
> Alternatively, consider a fusible link (4AWG
> smaller than B-lead). This will serve the same
> purpose and is often less expensive and more
> installer-friendly.
>
> As the Z-figures evolve, ANL and similar
> devices are going to be replaced with fusible
> links.
>
>
> Bob . . .
>
That's what I did. I confess to using a pair of off-the-shelf Denso
internally regulated alternators, with the OV protection on a pair of
continuous duty contactors on the firewall. The blue wires in the pic
are actually 12awg fusible link wire, doing double duty as interconnects
and protection for the 8awg B leads (~2 foot runs).
Needless to say, I'm a big fan of using links.
Charlie
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Sizing a B-lead ANL |
>That's what I did. I confess to using a pair of off-the-shelf Denso
>internally regulated alternators, with the OV protection on a pair
>of continuous duty contactors on the firewall. The blue wires in the
>pic are actually 12awg fusible link wire, doing double duty as
>interconnects and protection for the 8awg B leads (~2 foot runs).
>
>Needless to say, I'm a big fan of using links.
me too . . .
The probability of a hard-fault to a b-lead is exceedingly
low . . . but FMEA protocols do not consider 'exceedingly
low' . . . they ASSUME that if a failure is at all possible, then
design mitigation into the system.
This is how mission-reliability is promoted . . . mission
critical features of the airplane are first rendered
non-hazardous and then backed up by a system unlikely
to be affect by the same stresses while you finish consuming
one tank full of fuel. Hence, NO SYSTEM is really mission-
critical irrespective of the MTBF numbers.
ANL and similar devices are parts, installation and cost
intensive while adding an incalculably small if not
zero value to system reliability. So a piece of 'magic
wire' with a terminal on one end and splice on the other
seems quite practical.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|