Today's Message Index:
----------------------
1. 08:53 AM - Re: Tin Contact Finish (Robert L. Nuckolls, III)
2. 01:34 PM - Alternator failure mode (David Saylor)
3. 05:01 PM - Re: New smartphone app for pilots (rampil)
4. 08:44 PM - Re: Alternator failure mode (Robert L. Nuckolls, III)
5. 09:26 PM - Re: Alternator failure mode (David Saylor)
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: Tin Contact Finish |
At 10:26 PM 7/27/2016, you wrote:
>Folks,
>
>This has nothing to do with airplanes.
>
>I was idling away my evening browsing through
><http://digikey.com>digikey.com (don't ask me why this is fun!) and
>noticed some connectors are brass colored and others, like
><http://www.digikey.com/product-detail/en/te-connectivity-amp-connectors/170032-5/A100888CT-ND/2259557>http://www.digikey.com/product-detail/en/te-connectivity-amp-connectors/170032-5/A100888CT-ND/2259557
>, are grey. By carefully reading the specs, I see that the grey one
>is brass with a tin "contact finish".
>
>Why would you choose all brass vs. brass with a tin contact finish?
It's a combination of effects on performance influenced
by environmental stresses.
A freshly made up, bright metal joint is at that moment,
as good as it can get. But where the conductive materials
come together, there are usually risks for the surface
finished of those materials to degrade. Degradation
always raises the resistance of the joint. If the joint
carries much current, there's a snowballing effect that
leads to loss of integrity of the joint.
Connectors must have openable joints . . . you want to
plug and unplug the wires for installation and/or
maintenance. The interface between movable cannot
benefit from the advantages of gas-tight connections
offered by crimping or soldering.
Depending on criticality of the application and the
environment, bare brass might be just fine . . . one
example is in the fabrication of fast-on terminals
where by design, there is a lot of PRESSURE at the
interface.
Pins and sockets in connectors are another matter.
Here we generally see smooth bore female pins which
engage equally smooth male pins. Large area, low
pressure interface. Here you will probably never
see bare base metal pins. At a minimum, they will
be plated with tin or perhaps even gold.
Gold is the plating of choice for its resistance
to corrosion but tin is probably used in 90% of
terrestrial, consumer and industrial applications.
I've see some bare-metal products in fast-ons and
ring terminals but it's rare . . . and on very
pedestrian applications.
Bob . . .
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: | Alternator failure mode |
I just finished a leak check after other mx during which the alternator was
removed. All went well except I got an over-voltage. I started with the
field breaker pulled and before I even checked bus voltage just habitually
reset the field. It immediately popped. Then I saw the voltmeter at 18.1
and stable.
I shut down right away. All I could think was that I put the plug on the
alternator upside down so I checked that--turns out that's impossible and
it was well seated. So I plugged it back in, pulled the field breaker,
started the engine. Reset the breaker and everything is normal: I'm seeing
30+ amps at about 14.5V.
Installed:
PlanePower 12V internally regulated 60A.
Knuckolls crowbar overvoltage module
Two things are odd: the field breaker wouldn't reset right away after
shutdown. Maybe too hot?
And bus voltage was reading 18V even when the field breaker was popped. How
is that possible?
Any comments or explanations?
--Dave
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: New smartphone app for pilots |
Hi All,
Just a quick update that avAltimeter now supports iPads with Barometer hardware.
That includes the iPad Mini 4, the iPad Air 2, and the iPad Pro series, in addition
to the iPhone 6 and later.
The new version, 1.0.5, made it into the App Store today.
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=458887#458887
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: Alternator failure mode |
At 03:33 PM 7/29/2016, you wrote:
>I just finished a leak check after other mx
>during which the alternator was removed. All
>went well except I got an over-voltage. I
>started with the field breaker pulled and before
>I even checked bus voltage just habitually reset
>the field. It immediately popped. Then I saw the voltmeter at 18.1 and
stable.
18.1 volts AFTER the breaker popped?
>I shut down right away. All I could think was
>that I put the plug on the alternator upside
>down so I checked that--turns out that's=C2
>impossible and it was well seated. So I plugged
>it back in, pulled the field=C2 breaker, started
>the engine. Reset the breaker and everything is
>normal: =C2 I'm seeing 30+ amps at about 14.5V.
I thought PlanePower alternators were fitted
with their own ov protection. Can you share
a schematic of how your alternator is wired?
Are you using the field breaker as an alternator
control switch?
Bob . . .
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: Alternator failure mode |
I'll draw up a schematic but it's very standard. The OV module runs the
field to ground, as usual.
Yes, the OV continued after the breaker popped. I understand how weird
that seems--nothing in the system makes 18V. I'm glad it was just a leak
check and I was able to just shut down.
Now, I'm going by the VM in the EFIS. Could be a glitch there but until now
the built in VM has always been flawless. And the breaker wouldn't reset so
I believe it was in an OV condition. I can download the recoded data from
the run.
Yes, the breaker is the only control. Otherwise the alternator comes on
with the battery. I had the breaker pulled before start because of of some
extended battery-on tests.
Again, it didn't last long but it was very strange to see the OV and the
breaker popped--I had to tell myself to shut down instead of analyze,
before the magic smoke came out...
--Dave
PS: FWIW in the past I have, um, "tested" the OV module...we have both
flavors of GPU in the shop...the OV works great. --d
On Friday, July 29, 2016, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 03:33 PM 7/29/2016, you wrote:
>
> I just finished a leak check after other mx during which the alternator
> was removed. All went well except I got an over-voltage. I started with t
he
> field breaker pulled and before I even checked bus voltage just habituall
y
> reset the field. It immediately popped. Then I saw the voltmeter at 18.1
> and stable.
>
>
> 18.1 volts AFTER the breaker popped?
>
> I shut down right away. All I could think was that I put the plug on the
> alternator upside down so I checked that--turns out that's=C3=82 impossib
le and
> it was well seated. So I plugged it back in, pulled the field=C3=82 break
er,
> started the engine. Reset the breaker and everything is normal: =C3=82 I'
m
> seeing 30+ amps at about 14.5V.
>
>
> I thought PlanePower alternators were fitted
> with their own ov protection. Can you share
> a schematic of how your alternator is wired?
>
> Are you using the field breaker as an alternator
> control switch?
>
>
> Bob . . .
>
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! --
|