Today's Message Index:
----------------------
1. 05:43 AM - Re: diode on starter contactor (Alec Myers)
2. 07:38 AM - Re: diode on starter contactor (Eric Page)
3. 09:27 AM - Re: diode on starter contactor (Bernie Willis)
4. 09:50 AM - Re: diode on starter contactor (Alec Myers)
5. 09:58 AM - Re: diode on starter contactor (Bernie Willis)
6. 10:09 AM - Re: diode on starter contactor (Robert L. Nuckolls, III)
7. 10:13 AM - Re: diode on starter contactor (Robert L. Nuckolls, III)
8. 10:42 AM - Re: diode on starter contactor (Charlie England)
9. 12:17 PM - diode on starter contactor (Paul Millner)
10. 12:20 PM - Re: diode on starter contactor (Robert L. Nuckolls, III)
11. 01:40 PM - Re: diode on starter contactor (Eric Jones)
12. 01:56 PM - Re: diode on starter contactor (Alec Myers)
13. 01:56 PM - Re: diode on starter contactor (Ken Ryan)
14. 02:01 PM - Re: diode on starter contactor (Robert L. Nuckolls, III)
15. 02:39 PM - Re: diode on starter contactor (Alec Myers)
16. 04:50 PM - Re: diode on starter contactor (user9253)
17. 05:09 PM - Re: diode on starter contactor (Sebastien)
Message 1
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Subject: | Re: diode on starter contactor |
Inductors (a solenoid coil is a good example of a large inductor) resist sudden
changes in current flowing through them. When you energize the solenoid the current
through the coil grows slowly to its maximum value. When you break the
circuit with the switch you are forcing a sudden change in current, which causes
a massive voltage spike. In the microseconds after the switch contact breaks
the gap at the switch contacts is narrow enough, and the voltage rise at the
inductor is big enough, to cause arcing and contact damage in the switch.
The diode allows the current in the coil to continue to flow after the switch contact
is broken by completing the circuit from the ground terminal of the coil
back to the now-disconnected other terminal. (A diagram should make this clearer).
No sudden change in current means no sudden voltage rise and no possibility
of arcing.
The energy to drive the continuing current flow through the coil after the battery
power has been removed from the solenoid terminal comes from the energy stored
in the magnetic field. As the field collapses the current drops to zero.
On Jan 18, 2018, at 1:59 AM, Bill Bear <beartrax@mtaonline.net> wrote:
Bernie,
As I understand it, when the solenoid is deenergized, a voltage surge peak passes
through the circuit which ages the solenoid contacts. The diode prevents the
passage of the surge current and lengthens the life of the solenoid contacts.
The diode band end is connected to the positive side of the solenoid contractor
and the other side of the diode is connected to ground at the solenoid.
Bill
> On Jan 17, 2018, at 20:49, Bernie <arcticarrow@gmail.com> wrote:
>
> Im trying to follow the diode and the starter sol. discussion. I missed the reason
for the diode.
>
> Thanks
> Bernie
>
> Sent from my iPhone
>
> On Jan 17, 2018, at 4:38 PM, Ken Ryan <keninalaska@gmail.com> wrote:
>
>> Thanks everyone.
>>
>>
>> On Wed, Jan 17, 2018 at 3:35 PM, Alec Myers <alec@alecmyers.com> wrote:
>> Use the mounting bolt then, with a ring terminal under the bolt head.
>>
>> On Jan 17, 2018, at 19:18, Ken Ryan <keninalaska@gmail.com> wrote:
>>
>>> Alec, like I said in my original post, there is no ground terminal. Ground
is accomplished through the metal case.
>>>
>>> On Wed, Jan 17, 2018 at 3:10 PM, Alec Myers <alec@alecmyers.com> wrote:
>>>
>>> Wire it across the coil, so from non ground terminal to ground terminal, so
its reverse polarized when the coil is energized. Then when power is removed,
the magnetic field collapses driving current through the diode and avoiding a
large back emf.
>>>
>>> If you put it the wrong way round, dont worry, it will just disappear.
>>>
>>>
>>>
>>> On Jan 17, 2018, at 18:56, Ken Ryan <keninalaska@gmail.com> wrote:
>>>
>>> My starter contactor's coil gets its ground through the contactor's metal case.
Given that, does it make any sense to use a diode? If so, how would that
diode be implemented and how would it remain effective when the case itself is
the ground path?
>>>
>>> Ken
>>>
>>>
>>> ============
>>> -
>>> Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
>>> ==========
>>> FORUMS -
>>> eferrer" target="_blank">http://forums.matronics.com
>>> ==========
>>> WIKI -
>>> errer" target="_blank">http://wiki.matronics.com
>>> ==========
>>> b Site -
>>> -Matt Dralle, List Admin.
>>> rel="noreferrer" target="_blank">http://www.matronics.com/contribution
>>> ==========
>>>
>>>
>>>
>>>
>>
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Subject: | Re: diode on starter contactor |
Heres a really excellent video by a guy named Alan Wolke (an applications engineer
at Tektronix) that explains back-EMF in inductive circuits and the function
of snubber or flyback diodes.
https://www.youtube.com/watch?v=c6I7Ycbv8B8
As you watch this, keep in mind that Alan is using a small signal relay with a
relatively tiny coil that operates on a few tens of milliamps. Then consider
the typical starter solenoid: it should be obvious that the potential (pardon
the pun) for large voltage spikes is amplified by the physical size of its coil
and large current that it consumes in operation.
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=477413#477413
Message 3
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Subject: | Re: diode on starter contactor |
I really appreciate the discussion on the theory. Also found this issue discussed
in Aero Connection. I have an old Bonanza that occasionally produces a chattering
sound when the master/battery switch in turned on. Now I suspect it
is the master solenoid contacts showing signs of failure. A new solenoid is in
order but the diode protection seems in order also. A little research shows
diodes available in many voltage, capacitance and temperature rating, anything
from .07 to $300. What are the parameters of an appropriate diode to protect
a 12 volt master or starter solenoid?
Bernie
> On Jan 18, 2018, at 4:41 AM, Alec Myers <alec@alecmyers.com> wrote:
>
>
> Inductors (a solenoid coil is a good example of a large inductor) resist sudden
changes in current flowing through them. When you energize the solenoid the
current through the coil grows slowly to its maximum value. When you break the
circuit with the switch you are forcing a sudden change in current, which causes
a massive voltage spike. In the microseconds after the switch contact breaks
the gap at the switch contacts is narrow enough, and the voltage rise at the
inductor is big enough, to cause arcing and contact damage in the switch.
>
> The diode allows the current in the coil to continue to flow after the switch
contact is broken by completing the circuit from the ground terminal of the coil
back to the now-disconnected other terminal. (A diagram should make this clearer).
No sudden change in current means no sudden voltage rise and no possibility
of arcing.
>
> The energy to drive the continuing current flow through the coil after the battery
power has been removed from the solenoid terminal comes from the energy
stored in the magnetic field. As the field collapses the current drops to zero.
>
> On Jan 18, 2018, at 1:59 AM, Bill Bear <beartrax@mtaonline.net> wrote:
>
> Bernie,
>
> As I understand it, when the solenoid is deenergized, a voltage surge peak passes
through the circuit which ages the solenoid contacts. The diode prevents
the passage of the surge current and lengthens the life of the solenoid contacts.
The diode band end is connected to the positive side of the solenoid contractor
and the other side of the diode is connected to ground at the solenoid.
>
> Bill
>
>
>> On Jan 17, 2018, at 20:49, Bernie <arcticarrow@gmail.com> wrote:
>>
>> Im trying to follow the diode and the starter sol. discussion. I missed the
reason for the diode.
>>
>> Thanks
>> Bernie
>>
>> Sent from my iPhone
>>
>> On Jan 17, 2018, at 4:38 PM, Ken Ryan <keninalaska@gmail.com> wrote:
>>
>>> Thanks everyone.
>>>
>>>
>>> On Wed, Jan 17, 2018 at 3:35 PM, Alec Myers <alec@alecmyers.com> wrote:
>>> Use the mounting bolt then, with a ring terminal under the bolt head.
>>>
>>> On Jan 17, 2018, at 19:18, Ken Ryan <keninalaska@gmail.com> wrote:
>>>
>>>> Alec, like I said in my original post, there is no ground terminal. Ground
is accomplished through the metal case.
>>>>
>>>> On Wed, Jan 17, 2018 at 3:10 PM, Alec Myers <alec@alecmyers.com> wrote:
>>>>
>>>> Wire it across the coil, so from non ground terminal to ground terminal, so
its reverse polarized when the coil is energized. Then when power is removed,
the magnetic field collapses driving current through the diode and avoiding
a large back emf.
>>>>
>>>> If you put it the wrong way round, dont worry, it will just disappear.
>>>>
>>>>
>>>>
>>>> On Jan 17, 2018, at 18:56, Ken Ryan <keninalaska@gmail.com> wrote:
>>>>
>>>> My starter contactor's coil gets its ground through the contactor's metal
case. Given that, does it make any sense to use a diode? If so, how would that
diode be implemented and how would it remain effective when the case itself is
the ground path?
>>>>
>>>> Ken
>>>>
>>>>
>>>> ============
>>>> -
>>>> Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
>>>> ==========
>>>> FORUMS -
>>>> eferrer" target="_blank">http://forums.matronics.com
>>>> ==========
>>>> WIKI -
>>>> errer" target="_blank">http://wiki.matronics.com
>>>> ==========
>>>> b Site -
>>>> -Matt Dralle, List Admin.
>>>> rel="noreferrer" target="_blank">http://www.matronics.com/contribution
>>>> ==========
>>>>
>>>>
>>>>
>>>>
>>>
>
>
>
>
>
>
Message 4
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Subject: | Re: diode on starter contactor |
A ten cent 1N4001 is just fine.
Voltage refers to a safe reverse voltage limit before avalanche breakdown: the
coil diode is only reverse biased to 12V. A 1N4001 is rated to 50V.
Current rating: somewhat irrelevant, since theres no sustained current load. A
1N4001 is good for up to 1A continuous, and 30A surge. Neither limit will be close
to met in this application.
Capacitance: refers to the junction capacitance when reverse biased. Irrelevant
in this application.
Physical package: anything big enough to solder easily will have enough thermal
mass to absorb what little energy is stored in the coil magnetic field.
On Jan 18, 2018, at 12:26 PM, Bernie Willis <arcticarrow@gmail.com> wrote:
I really appreciate the discussion on the theory. Also found this issue discussed
in Aero Connection. I have an old Bonanza that occasionally produces a chattering
sound when the master/battery switch in turned on. Now I suspect it
is the master solenoid contacts showing signs of failure. A new solenoid is in
order but the diode protection seems in order also. A little research shows
diodes available in many voltage, capacitance and temperature rating, anything
from .07 to $300. What are the parameters of an appropriate diode to protect
a 12 volt master or starter solenoid?
Bernie
> On Jan 18, 2018, at 4:41 AM, Alec Myers <alec@alecmyers.com> wrote:
>
>
> Inductors (a solenoid coil is a good example of a large inductor) resist sudden
changes in current flowing through them. When you energize the solenoid the
current through the coil grows slowly to its maximum value. When you break the
circuit with the switch you are forcing a sudden change in current, which causes
a massive voltage spike. In the microseconds after the switch contact breaks
the gap at the switch contacts is narrow enough, and the voltage rise at the
inductor is big enough, to cause arcing and contact damage in the switch.
>
> The diode allows the current in the coil to continue to flow after the switch
contact is broken by completing the circuit from the ground terminal of the coil
back to the now-disconnected other terminal. (A diagram should make this clearer).
No sudden change in current means no sudden voltage rise and no possibility
of arcing.
>
> The energy to drive the continuing current flow through the coil after the battery
power has been removed from the solenoid terminal comes from the energy
stored in the magnetic field. As the field collapses the current drops to zero.
>
> On Jan 18, 2018, at 1:59 AM, Bill Bear <beartrax@mtaonline.net> wrote:
>
> Bernie,
>
> As I understand it, when the solenoid is deenergized, a voltage surge peak passes
through the circuit which ages the solenoid contacts. The diode prevents
the passage of the surge current and lengthens the life of the solenoid contacts.
The diode band end is connected to the positive side of the solenoid contractor
and the other side of the diode is connected to ground at the solenoid.
>
> Bill
>
>
>> On Jan 17, 2018, at 20:49, Bernie <arcticarrow@gmail.com> wrote:
>>
>> Im trying to follow the diode and the starter sol. discussion. I missed the
reason for the diode.
>>
>> Thanks
>> Bernie
>>
>> Sent from my iPhone
>>
>> On Jan 17, 2018, at 4:38 PM, Ken Ryan <keninalaska@gmail.com> wrote:
>>
>>> Thanks everyone.
>>>
>>>
>>> On Wed, Jan 17, 2018 at 3:35 PM, Alec Myers <alec@alecmyers.com> wrote:
>>> Use the mounting bolt then, with a ring terminal under the bolt head.
>>>
>>> On Jan 17, 2018, at 19:18, Ken Ryan <keninalaska@gmail.com> wrote:
>>>
>>>> Alec, like I said in my original post, there is no ground terminal. Ground
is accomplished through the metal case.
>>>>
>>>> On Wed, Jan 17, 2018 at 3:10 PM, Alec Myers <alec@alecmyers.com> wrote:
>>>>
>>>> Wire it across the coil, so from non ground terminal to ground terminal, so
its reverse polarized when the coil is energized. Then when power is removed,
the magnetic field collapses driving current through the diode and avoiding
a large back emf.
>>>>
>>>> If you put it the wrong way round, dont worry, it will just disappear.
>>>>
>>>>
>>>>
>>>> On Jan 17, 2018, at 18:56, Ken Ryan <keninalaska@gmail.com> wrote:
>>>>
>>>> My starter contactor's coil gets its ground through the contactor's metal
case. Given that, does it make any sense to use a diode? If so, how would that
diode be implemented and how would it remain effective when the case itself is
the ground path?
>>>>
>>>> Ken
>>>>
>>>>
>>>> ============
>>>> -
>>>> Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
>>>> ==========
>>>> FORUMS -
>>>> eferrer" target="_blank">http://forums.matronics.com
>>>> ==========
>>>> WIKI -
>>>> errer" target="_blank">http://wiki.matronics.com
>>>> ==========
>>>> b Site -
>>>> -Matt Dralle, List Admin.
>>>> rel="noreferrer" target="_blank">http://www.matronics.com/contribution
>>>> ==========
>>>>
>>>>
>>>>
>>>>
>>>
>
>
>
>
>
>
Message 5
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Subject: | Re: diode on starter contactor |
Alec,
That was a quick reply! Now I can proceed.
Thanks,
Bernie
> On Jan 18, 2018, at 8:49 AM, Alec Myers <alec@alecmyers.com> wrote:
>
>
> A ten cent 1N4001 is just fine.
>
> Voltage refers to a safe reverse voltage limit before avalanche breakdown: the
coil diode is only reverse biased to 12V. A 1N4001 is rated to 50V.
> Current rating: somewhat irrelevant, since theres no sustained current load.
A 1N4001 is good for up to 1A continuous, and 30A surge. Neither limit will be
close to met in this application.
> Capacitance: refers to the junction capacitance when reverse biased. Irrelevant
in this application.
> Physical package: anything big enough to solder easily will have enough thermal
mass to absorb what little energy is stored in the coil magnetic field.
>
>
>
>
>
> On Jan 18, 2018, at 12:26 PM, Bernie Willis <arcticarrow@gmail.com> wrote:
>
>
> I really appreciate the discussion on the theory. Also found this issue discussed
in Aero Connection. I have an old Bonanza that occasionally produces a
chattering sound when the master/battery switch in turned on. Now I suspect it
is the master solenoid contacts showing signs of failure. A new solenoid is
in order but the diode protection seems in order also. A little research shows
diodes available in many voltage, capacitance and temperature rating, anything
from .07 to $300. What are the parameters of an appropriate diode to protect
a 12 volt master or starter solenoid?
>
> Bernie
>
>> On Jan 18, 2018, at 4:41 AM, Alec Myers <alec@alecmyers.com> wrote:
>>
>>
>> Inductors (a solenoid coil is a good example of a large inductor) resist sudden
changes in current flowing through them. When you energize the solenoid the
current through the coil grows slowly to its maximum value. When you break the
circuit with the switch you are forcing a sudden change in current, which causes
a massive voltage spike. In the microseconds after the switch contact breaks
the gap at the switch contacts is narrow enough, and the voltage rise at
the inductor is big enough, to cause arcing and contact damage in the switch.
>>
>> The diode allows the current in the coil to continue to flow after the switch
contact is broken by completing the circuit from the ground terminal of the
coil back to the now-disconnected other terminal. (A diagram should make this
clearer). No sudden change in current means no sudden voltage rise and no possibility
of arcing.
>>
>> The energy to drive the continuing current flow through the coil after the battery
power has been removed from the solenoid terminal comes from the energy
stored in the magnetic field. As the field collapses the current drops to zero.
>>
>> On Jan 18, 2018, at 1:59 AM, Bill Bear <beartrax@mtaonline.net> wrote:
>>
>> Bernie,
>>
>> As I understand it, when the solenoid is deenergized, a voltage surge peak passes
through the circuit which ages the solenoid contacts. The diode prevents
the passage of the surge current and lengthens the life of the solenoid contacts.
The diode band end is connected to the positive side of the solenoid contractor
and the other side of the diode is connected to ground at the solenoid.
>>
>> Bill
>>
>>
>>> On Jan 17, 2018, at 20:49, Bernie <arcticarrow@gmail.com> wrote:
>>>
>>> Im trying to follow the diode and the starter sol. discussion. I missed the
reason for the diode.
>>>
>>> Thanks
>>> Bernie
>>>
>>> Sent from my iPhone
>>>
>>> On Jan 17, 2018, at 4:38 PM, Ken Ryan <keninalaska@gmail.com> wrote:
>>>
>>>> Thanks everyone.
>>>>
>>>>
>>>> On Wed, Jan 17, 2018 at 3:35 PM, Alec Myers <alec@alecmyers.com> wrote:
>>>> Use the mounting bolt then, with a ring terminal under the bolt head.
>>>>
>>>> On Jan 17, 2018, at 19:18, Ken Ryan <keninalaska@gmail.com> wrote:
>>>>
>>>>> Alec, like I said in my original post, there is no ground terminal. Ground
is accomplished through the metal case.
>>>>>
>>>>> On Wed, Jan 17, 2018 at 3:10 PM, Alec Myers <alec@alecmyers.com> wrote:
>>>>>
>>>>> Wire it across the coil, so from non ground terminal to ground terminal,
so its reverse polarized when the coil is energized. Then when power is removed,
the magnetic field collapses driving current through the diode and avoiding
a large back emf.
>>>>>
>>>>> If you put it the wrong way round, dont worry, it will just disappear.
>>>>>
>>>>>
>>>>>
>>>>> On Jan 17, 2018, at 18:56, Ken Ryan <keninalaska@gmail.com> wrote:
>>>>>
>>>>> My starter contactor's coil gets its ground through the contactor's metal
case. Given that, does it make any sense to use a diode? If so, how would that
diode be implemented and how would it remain effective when the case itself
is the ground path?
>>>>>
>>>>> Ken
>>>>>
>>>>>
>>>>> ============
>>>>> -
>>>>> Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
>>>>> ==========
>>>>> FORUMS -
>>>>> eferrer" target="_blank">http://forums.matronics.com
>>>>> ==========
>>>>> WIKI -
>>>>> errer" target="_blank">http://wiki.matronics.com
>>>>> ==========
>>>>> b Site -
>>>>> -Matt Dralle, List Admin.
>>>>> rel="noreferrer" target="_blank">http://www.matronics.com/contribution
>>>>> ==========
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
>
>
>
>
>
Message 6
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Subject: | Re: diode on starter contactor |
At 11:49 PM 1/17/2018, you wrote:
>I=99m trying to follow the diode and the starter
>sol. discussion. I missed the reason for the diode.
We've had several discussions on spike-suppression
diodes on relays and contactors over the years. One
of the first was prompted by a snafu over an
airworthiness directive against the ACS/Gerdes
off-left-right-on-start key switches. Seems
the inductive spike fire generated by relatively
high coil current of some starter contactors was
eating up the start contact in the key switch.
Here's one example of a OEM aircafter's response
to the AD.
https://goo.gl/1XvDtj
This was the CORRECT way to install the diode . . .
the AD also called for refurbishment of the
start switch contacts within the keyswitch.
Here's background on the physics for proper
placement of the diode.
https://goo.gl/WUS1Ya
The problem would get potentially worse when
lightweight starters started showing up.
Still more stress on the switch was a function of
a two-stage engagement scenario which impressed a much larger
engagement inrush current compared to legacy
starter contactors. Here's the background.
https://goo.gl/opeqsM
Later in the discussions, there was consternation
about how 'inadvised' configuration of spike
suppression would cause the contactor's points
to open more slowly and exacerbate contact wear.
The assertion was predicated on an article published
by Potter-Brumfield
https://goo.gl/iCrqch
The author asserts that a diode connected right
across the contactor/relay coil results in significantly
slower contact opening velocity. This prompted a
trip to the workbench to explore the physics:
https://goo.gl/KNTr8y
For our purposes, the diode was demonstrated to
effect a DELAY in contact first opening . . . but
once the contacts started to move, the AIR GAP
in the magnetic circuit had a much more profound
effect on opening velocity than did the slower
decay of current in the contactor coil.
The short answer is that adding a plain-jane diode
across the coil of any relay or contactor in
the airplane will not noticeably affect service
life of that device. The diode improves service
life of the SWITCH THAT CONTROLS THE CONTACTOR.
Further, contactor coils do not propagate spikes
onto the system looking for vulnerable solid
state electronics to fry.
Bob . . .
Message 7
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Subject: | Re: diode on starter contactor |
At 11:49 AM 1/18/2018, you wrote:
>
>A ten cent 1N4001 is just fine.
>
>Voltage refers to a safe reverse voltage limit
>before avalanche breakdown: the coil diode is
>only reverse biased to 12V. A 1N4001 is rated to 50V.
>Current rating: somewhat irrelevant, since
>there=99s no sustained current load. A 1N4001 is
>good for up to 1A continuous, and 30A surge.
>Neither limit will be close to met in this application.
Absolutely correct. My personal favorites
are the 1N5400 series devices, NOT for their
electrical ratings but for mechanical
robustness. Example:
https://goo.gl/2CGXgf
Bob . . .
Message 8
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Subject: | Re: diode on starter contactor |
On 1/18/2018 12:13 PM, Robert L. Nuckolls, III wrote:
> At 11:49 AM 1/18/2018, you wrote:
>>
>> A ten cent 1N4001 is just fine.
>>
>> Voltage refers to a safe reverse voltage limit before avalanche
>> breakdown: the coil diode is only reverse biased to 12V. A 1N4001 is
>> rated to 50V.
>> Current rating: somewhat irrelevant, since theres no sustained
>> current load. A 1N4001 is good for up to 1A continuous, and 30A
>> surge. Neither limit will be close to met in this application.
>
> Absolutely correct. My personal favorites
> are the 1N5400 series devices, NOT for their
> electrical ratings but for mechanical
> robustness. Example:
>
> https://goo.gl/2CGXgf
>
>
> Bob . . .
>
And, while I haven't priced the 5400 series, the 4000 series prices used
to be virtually identical from 4001 to 4007 (1KV rating). Not that you'd
need it for this application, but when I repaired electrons for a
living, we just stocked the 07s because they work for everything at that
current rating.
---
This email has been checked for viruses by Avast antivirus software.
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Message 9
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Subject: | diode on starter contactor |
>> when the solenoid is de-energized, a voltage surge peak passes
through the circuit which ages the solenoid contacts. The diode prevents
the passage of the surge current and lengthens the life of the solenoid
contacts.
For an abundance of clarity, the diode across the coil terminals does
NOT protect the solenoid's contacts. It protects instead the switch
contacts of whatever switch controls that solenoid coil: the starter
switch for the starter contactor; the master switch contacts for the
master contactor.
Paul
Message 10
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Subject: | Re: diode on starter contactor |
>> Bob . . .
>And, while I haven't priced the 5400 series, the 4000 series prices
>used to be virtually identical from 4001 to 4007 (1KV rating). Not
>that you'd need it for this application, but when I repaired
>electrons for a living, we just stocked the 07s because they work
>for everything at that current rating.
Astute observation.
I've not confirmed this with a real diode-maker
person but . . .
I was working at a nuclear fuels manufacturing
company in Apollo, PA where a colleague asserted
that variously rated diodes were all made on the
same line. They were screened for breakdown voltage
looking first for devices that would function as
1000 volt devices. When the order for 007 parts
was 'filled', the next screen was for the lower
voltage part with the lowest breakdown would
be marked 000.
Over the years, production variability went down
to the point where virtually all parts would make
the cut for 1kV parts. But rather than upset the
legacy apple-cart, they continued to market the
lower voltage part numbers . . . which were in
fact 1 kV devices.
Somewhere around here I've got a 2 kV power
supply. It would be interesting to see just how
far one can push the modern LV parts . . . but
that ain't happ'ng soon . . .
Bob . . .
Message 11
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Subject: | Re: diode on starter contactor |
This subject has been discussed here for years.
My opinion and what I have suggested for years is that the current best
practice is to use bidirectional zener diodes. Regular diodes are
problematic. See attached.
You can use what I suggest or slightly heavier ones for better
mechanical properties. (I am currently shipping the 5KE20CA parts).
Eric M. Jones
-Bought a 177RG Cardinal.
Message 12
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Subject: | Re: diode on starter contactor |
Eric,
I see great marketing (FUD) in that document but no actual information.
What do you believe to be the problem with a regular diode?
On Jan 18, 2018, at 4:38 PM, Eric Jones <emjones@charter.net> wrote:
This subject has been discussed here for years.
My opinion and what I have suggested for years is that the current best practice
is to use bidirectional zener diodes. Regular diodes are problematic. See attached.
You can use what I suggest or slightly heavier ones for better mechanical properties.
(I am currently shipping the 5KE20CA parts).
Eric M. Jones
-Bought a 177RG Cardinal.
<SnapJacks.pdf>
Message 13
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Subject: | Re: diode on starter contactor |
Eric, is it okay to solder a wire to your snapjacks?
On Thu, Jan 18, 2018 at 12:38 PM, Eric Jones <emjones@charter.net> wrote:
> This subject has been discussed here for years.
>
> My opinion and what I have suggested for years is that the current best
> practice is to use bidirectional zener diodes. Regular diodes are
> problematic. See attached.
>
> You can use what I suggest or slightly heavier ones for better mechanical
> properties. (I am currently shipping the 5KE20CA parts).
>
> Eric M. Jones
>
> -Bought a 177RG Cardinal.
>
>
Message 14
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Subject: | Re: diode on starter contactor |
At 03:38 PM 1/18/2018, you wrote:
>This subject has been discussed here for years.
>
>My opinion and what I have suggested for years is that the current
>best practice is to use bidirectional zener diodes. Regular diodes
>are problematic. See attached.
Emacs!
Can you demonstrate this? "Excessive" is non-quantified.
Was my bench top study flawed in some way?
Bob . . .
Message 15
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Subject: | Re: diode on starter contactor |
Im trying to work out why a diode has *any* significant effect on release time
compared to a tranzorb or similar, and if it did, why you might care.
Also, why should it have any effect on relay life reduction ?
My skeptical self needs help to get beyond merely more expensive therefore must
be better.
On Jan 18, 2018, at 5:01 PM, Robert L. Nuckolls, III <nuckolls.bob@aeroelectric.com>
wrote:
At 03:38 PM 1/18/2018, you wrote:
> This subject has been discussed here for years.
>
> My opinion and what I have suggested for years is that the current best practice
is to use bidirectional zener diodes. Regular diodes are problematic. See
attached.
<f1b501.jpg>
Can you demonstrate this? "Excessive" is non-quantified.
Was my bench top study flawed in some way?
Bob . . .
Message 16
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Subject: | Re: diode on starter contactor |
A capacitor opposes any change in voltage.
An inductor (coil) opposes any change in current.
When the switch is closed (Figure 1), positive
current flows from left to right through the coil.
The diode does not conduct because positive
current can not flow against the arrow.
_
When the switch is opened (Figure 2), the
coil opposes any change and tries to
maintain the current. The coil is no longer a load.
The coil is now a source, like a battery.
Induced current still flows in the same direction
through the coil from left to right.
But the polarity has changed because
because the coil is now a source, not a load.
The diode now conducts because positive on
the right side flows with the arrow. Current
always tries to return to the source, the coil in
this case. It takes the path of least resistance,
which is through the diode, not across the open
switch contacts. The induced voltage is limited
to the forward voltage drop across the diode.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=477433#477433
Attachments:
http://forums.matronics.com//files/inductor__213.jpg
Message 17
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Subject: | Re: diode on starter contactor |
Last year I put a lighter AGM battery in my aircraft and moved it to the
firewall along with the master contactor and made some new diodes for the
contactors (one was broken). Saved about 4 pounds in wiring alone! Only
problem afterwards was that if the battery was even slightly down sometimes
the starter would turn a split second and then nothing. Repeated attempts
usually ended up with the starter eventually running fine until the engine
started. Putting a voltmeter on the starter confirmed that the problem was
a lack of power to the starter, not the starter itself. I had a battery
problem later on and replaced the battery, no change. Thinking I had messed
up the starter contactor while tightening nuts on it I swapped it out, no
change. At this point I started to suspect my diode so I disconnected it:
Problem gone! I suspect I installed it backwards. Going to make the new one
with clear shrinkwrap tubing so it can't happen again.
On Thu, Jan 18, 2018 at 2:37 PM, Alec Myers <alec@alecmyers.com> wrote:
>
> I=99m trying to work out why a diode has *any* significant effect o
n release
> time compared to a tranzorb or similar, and if it did, why you might care
.
> Also, why should it have any effect on relay life reduction ?
>
> My skeptical self needs help to get beyond merely =9Cmore expensive
> therefore must be better=9D.
>
>
> On Jan 18, 2018, at 5:01 PM, Robert L. Nuckolls, III <
> nuckolls.bob@aeroelectric.com> wrote:
>
> At 03:38 PM 1/18/2018, you wrote:
> > This subject has been discussed here for years.
> >
> > My opinion and what I have suggested for years is that the current best
> practice is to use bidirectional zener diodes. Regular diodes are
> problematic. See attached.
>
> <f1b501.jpg>
>
> Can you demonstrate this? "Excessive" is non-quantified.
> Was my bench top study flawed in some way?
>
>
> Bob . . .
>
>
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