Today's Message Index:
----------------------
1. 02:28 AM - How electricity works (l.p@talk21.com)
2. 06:40 AM - Re: How electricity works (user9253)
3. 09:21 AM - Re: Power-Sonic LiFePO4 (Hypersport) (Charlie England)
4. 09:25 AM - Re: Any ideas where to get electric motor brushes? (Robert L. Nuckolls, III)
5. 09:38 AM - Re: Any ideas where to get electric motor brushes? (John B)
6. 09:38 AM - Re: Any ideas where to get electric motor brushes? (Robert L. Nuckolls, III)
7. 09:50 AM - Re: Re: How electricity works (Charlie England)
8. 09:54 AM - Re: Any ideas where to get electric motor brushes? (Charlie England)
9. 10:25 AM - Re: Any ideas where to get electric motor brushes? (Joel Ventura)
10. 01:42 PM - D-Sub High Density 78 female - solfder or crimp contacts (rd2)
11. 02:17 PM - Re: Any ideas where to get electric motor brushes? (rparigoris)
12. 02:45 PM - Re: Re: Any ideas where to get electric motor brushes? (Robert L. Nuckolls, III)
13. 02:50 PM - Re: Re: Any ideas where to get electric motor brushes? (Charlie England)
14. 02:50 PM - Re: D-Sub High Density 78 female - solfder or crimp contacts (SteinB)
15. 02:52 PM - Re: D-Sub High Density 78 female - solfder or crimp contacts (Robert L. Nuckolls, III)
16. 05:11 PM - Re: D-Sub High Density 78 female - solfder or crimp contacts (Robert L. Nuckolls, III)
17. 05:24 PM - Re: Any ideas where to get electric motor brushes? (rparigoris)
18. 05:47 PM - Re: Any ideas where to get electric motor brushes? (rparigoris)
19. 05:47 PM - Connector advice (Daryl Thompson)
20. 05:51 PM - Re: Power-Sonic LiFePO4 (Hypersport) (Robert L. Nuckolls, III)
21. 06:06 PM - Re: Re: Any ideas where to get electric motor brushes? (Robert L. Nuckolls, III)
22. 06:11 PM - Re: Re: Any ideas where to get electric motor brushes? (Robert L. Nuckolls, III)
23. 06:59 PM - Re: Any ideas where to get electric motor brushes? (rparigoris)
Message 1
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| Subject: | How electricity works |
Dear Bob et al.
I have a question on how electricity works in relation to components in
our obam aircraft and hope you can help my understanding.
I have a unit that has a power requirement of 15 amps.
It is my intention to control this unit utilising a relay.
I wish to control the relay with a micro-switch.
I'll at first wire up the relay as per Z diagrams where the main power
supply wire to the relay, and thence unit, is also the power for the
relay operating coil.
Starting with the micro-switch contacts open and no current flowing, on
closing the micro-switch contacts and power flows through the coil I'd
imagine the relay's coil needs and only "takes" little amperage.
At this point the relay's contacts close and the same power supply wire
now feeds through to the unit at the amperage it needs.
My question is; will the micro-switch and its small gauge wires also
"see" the 15 amps that the unit will take?
I could wire up the micro-switch and relay coil separate to the power to
the unit, but I'm generally wondering how components "choose" their
amount of current and if I can use one less wire here safely?
Hoping you can help increase my knowledge, thanks.
Patrick Elliott
Message 2
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| Subject: | Re: How electricity works |
No, the micro switch will not "see" 15 amps. The switch will only conduct relay
coil current.
Current through the switch is limited by the resistance of the relay coil.
A diode should be installed across the relay coil to prevent arcing and
sparking across the switch contacts, thus prolonging the life of the switch.
The banded end of the diode must be connected to the positive side of the coil.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=499980#499980
Message 3
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| Subject: | Re: Power-Sonic LiFePO4 (Hypersport) |
On 1/1/2021 9:53 AM, Patrick Brannan wrote:
>
> Hi,
>
> TLDR; The PAL50N18L LiFePO4 (Hypersport) is rated at 128 W/Hr. I
> tested at currents between 12.5 and 20 amps and found the capacity was
> at least 260 W/Hr. At well under $200 is this a fantastic bargain in
> batteries, or have I missed something?
>
> Im building a Marquart Charger with an electrically dependent engine
> using SDS EFII. I settled on a single alternator / 2 battery system. I
> forget Bobs schematic # but its one of them. My objective is to have
> a comfortable amount of flying time in the event of an alternator
> failure. To compensate for a failure of one battery or the other, each
> of the batteries needs to be able to run the engine for a reasonable
> amount of time. I believe that with a single boost pump operating I
> will have a current consumption of a little under 10 amps. The
> Marquart Charge is an open cockpit biplane.
>
> Anyway, I took a plunge and bought a Power-Sonic PAL50N18L LiFePO4.
> Yesterday I started testing it, and I want to share the results for 2
> reasons. 1) Help out somebody looking for a battery like this. 2)
> Double check my experimental results to make sure they are correct.
>
> For my test I bought a cheap battery monitor from Amazon and used a
> Lectron 10A hobby charger. The battery monitor uses a 75mv - 100A
> shunt. The battery monitors current readings were verified by the
> voltage drop across the shunt, my multimeter hooked up in series at
> less than 10A, and also the Lectron chargers AH numbers. If the
> battery monitor says that you took out 20.3 Ah the Lectron will put
> very close to 20.3 Ah back in. So even though Im using cheap stuff, I
> think its fairly accurate.
>
> I loaded the battery with a 400W inverter running a work light and a
> box fan. Pictures are attached.
>
> Does this all make sense? I think a LiFePO4 that pushes twice the
> rated Ah is unusual. I will say that Power-Sonic says the battery
> weights 4 lbs. It really weighs 6. The folks at PLPBattery were great.
> When I told them the battery was overweight they weight every other
> Power-Sonic battery. According to them, this is the only model that is
> overweight.
>
> Pat
>
Double the rated total energy sounds like a mislabeled battery. ;-)
Supporting that would be the 50% greater weight than spec. The PS
datasheet for that model says that the 'cutoff' point should be 12.8V,
and their discharge graph shows a 7.5A load discharging to ~12.8V at
around 50 minutes. That '128WH' number means that even though the model
number makes you 'feel' like it's an 18 AH battery (using typical SLA
nomenclature), it's really a 10AH battery. If I were electrically
dependent, I'd treat that number as the absolute best case, and de-rate
by close to 50% to account for variations in quality, load, aging
factors, etc.
EFI, including the fuel pump, *might* consume as low as 10 amps, but I'd
want to verify that in actual operation; not by 'faith'. The fuel pump
alone will consume somewhere between 4.5 & 8 amps, depending on model.
To the engine electrical consumption, you need to add whatever
additional loads needed in the plane.
FWIW,
Charlie
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Message 4
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| Subject: | Re: Any ideas where to get electric motor brushes? |
At 10:43 PM 1/3/2021, you wrote:
>
>Hi Group
>I need some brushes for the exciter on my Monarch EE lathe. Was
>making some aeroplane parts and it quit.
>Sizes needed:
>3/8" x 3/8" and worn out length is 1.060", it has a shunt and
>terminal (need 4, will buy 8)
>1/2" x 1/4" and worn out length is .495", it has a shunt and
>terminal (need 2, will buy 4)
>Any ideas where I can purchase from?
About 40 years ago I had ready access to
a stockroom of brushes that would probably
have yielded something that would cut-down
to suitable profiles. Alas, no more.
There are listings on eBay (40,000+) that
might produce useful candidates but most
come out of China . . . so it depends on your
urgency.
I've cut down many a brush on a mill. In
your case, avoid brushes destined for use
in h9gh current, intermittent motors like
starter and winch motors.
There are hundreds of 'recipes' for brush
make-up . . . unless you order spares from
the original manufacturer of you motor,
finding an exact replacement for size and
content is problematic.
However, for anything less then high duty
cycle applications, optimization of recipe
will have little significance on service
life of your substitution.
You might research DC motor overhaul
services on the 'net. They may have
spares suitable for modification if not
okay as-is. Keep your old springs if they're
not obviously compromised.
1" is pretty long for a worn brush . . . 1/2"
values are quite common. Is that in a 4-pole
motor? What are the nameplate sizes for these
motors?
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
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| Subject: | Re: Any ideas where to get electric motor brushes? |
McMaster-Carr has a nice selection of brushes available.
On Mon, Jan 4, 2021 at 11:29 AM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 10:43 PM 1/3/2021, you wrote:
>
> rparigor@hotmail.com>
>
> Hi Group
> I need some brushes for the exciter on my Monarch EE lathe. Was making
> some aeroplane parts and it quit.
> Sizes needed:
> 3/8" x 3/8" and worn out length is 1.060", it has a shunt and terminal
> (need 4, will buy 8)
> 1/2" x 1/4" and worn out length is .495", it has a shunt and terminal
> (need 2, will buy 4)
> Any ideas where I can purchase from?
>
>
> About 40 years ago I had ready access to
> a stockroom of brushes that would probably
> have yielded something that would cut-down
> to suitable profiles. Alas, no more.
>
> There are listings on eBay (40,000+) that
> might produce useful candidates but most
> come out of China . . . so it depends on your
> urgency.
>
> I've cut down many a brush on a mill. In
> your case, avoid brushes destined for use
> in h9gh current, intermittent motors like
> starter and winch motors.
>
> There are hundreds of 'recipes' for brush
> make-up . . . unless you order spares from
> the original manufacturer of you motor,
> finding an exact replacement for size and
> content is problematic.
>
> However, for anything less then high duty
> cycle applications, optimization of recipe
> will have little significance on service
> life of your substitution.
>
> You might research DC motor overhaul
> services on the 'net. They may have
> spares suitable for modification if not
> okay as-is. Keep your old springs if they're
> not obviously compromised.
>
> 1" is pretty long for a worn brush . . . 1/2"
> values are quite common. Is that in a 4-pole
> motor? What are the nameplate sizes for these
> motors?
>
>
> 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
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| Subject: | Re: Any ideas where to get electric motor brushes? |
At 10:43 PM 1/3/2021, you wrote:
>
>Hi Group
>I need some brushes for the exciter on my Monarch EE lathe. Was
>making some aeroplane parts and it quit.
>Sizes needed:
>3/8" x 3/8" and worn out length is 1.060", it has a shunt and
>terminal (need 4, will buy 8)
>1/2" x 1/4" and worn out length is .495", it has a shunt and
>terminal (need 2, will buy 4)
>Any ideas where I can purchase from?
check out these guys https://tinyurl.com/yczw98h4 and no doubt
there are others.
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 7
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| Subject: | Re: How electricity works |
*Dear Bob et al.I have a question on how electricity works in relation to
components in our obam aircraft and hope you can help my understanding.I
have a unit that has a power requirement of 15 amps.It is my intention to
control this unit utilising a relay.I wish to control the relay with a
micro-switch.I'll at first wire up the relay as per Z diagrams where the
main power supply wire to the relay, and thence unit, is also the power for
the relay operating coil.Starting with the micro-switch contacts open and
no current flowing, on closing the micro-switch contacts and power flows
through the coil I'd imagine the relay's coil needs and only "takes" little
amperage.At this point the relay's contacts close and the same power supply
wire now feeds through to the unit at the amperage it needs.My question is;
will the micro-switch and its small gauge wires also "see" the 15 amps that
the unit will take?I could wire up the micro-switch and relay coil separate
to the power to the unit, but I'm generally wondering how components
"choose" their amount of current and if I can use one less wire here
safely?Hoping you can help increase my knowledge, thanks.Patrick Elliott*
On Mon, Jan 4, 2021 at 8:44 AM user9253 <fransew@gmail.com> wrote:
>
> No, the micro switch will not "see" 15 amps. The switch will only conduct
> relay coil current.
> Current through the switch is limited by the resistance of the relay coil.
> A diode should be installed across the relay coil to prevent arcing and
> sparking across the switch contacts, thus prolonging the life of the
> switch.
> The banded end of the diode must be connected to the positive side of the
> coil.
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=499980#499980
The 'one wire' question is electrically ok, but might not make logistical
sense, unless the high current load is very close to the microswitch
control point. If that's your situation, then it's no big deal to jump from
the high current supply terminal of the relay to the supply side of the
microswitch, then from the load side of the microswitch to the supply side
of the relay coil. (Pay attention to the length and damage-risk of the run
from relay 'hot' to microswitch; that will be 'unprotected' due to the high
current fusing for your primary load.)
Charlie
Message 8
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| Subject: | Re: Any ideas where to get electric motor brushes? |
Have you tried Monarch
<https://monarchlathe.com/products/lathes/toolroom/monarch-ee-series>?
On Mon, Jan 4, 2021 at 11:43 AM John B <jbsoar@gmail.com> wrote:
> McMaster-Carr has a nice selection of brushes available.
>
> On Mon, Jan 4, 2021 at 11:29 AM Robert L. Nuckolls, III <
> nuckolls.bob@aeroelectric.com> wrote:
>
>> At 10:43 PM 1/3/2021, you wrote:
>>
>> rparigor@hotmail.com>
>>
>> Hi Group
>> I need some brushes for the exciter on my Monarch EE lathe. Was making
>> some aeroplane parts and it quit.
>> Sizes needed:
>> 3/8" x 3/8" and worn out length is 1.060", it has a shunt and terminal
>> (need 4, will buy 8)
>> 1/2" x 1/4" and worn out length is .495", it has a shunt and terminal
>> (need 2, will buy 4)
>> Any ideas where I can purchase from?
>>
>>
>> About 40 years ago I had ready access to
>> a stockroom of brushes that would probably
>> have yielded something that would cut-down
>> to suitable profiles. Alas, no more.
>>
>> There are listings on eBay (40,000+) that
>> might produce useful candidates but most
>> come out of China . . . so it depends on your
>> urgency.
>>
>> I've cut down many a brush on a mill. In
>> your case, avoid brushes destined for use
>> in h9gh current, intermittent motors like
>> starter and winch motors.
>>
>> There are hundreds of 'recipes' for brush
>> make-up . . . unless you order spares from
>> the original manufacturer of you motor,
>> finding an exact replacement for size and
>> content is problematic.
>>
>> However, for anything less then high duty
>> cycle applications, optimization of recipe
>> will have little significance on service
>> life of your substitution.
>>
>> You might research DC motor overhaul
>> services on the 'net. They may have
>> spares suitable for modification if not
>> okay as-is. Keep your old springs if they're
>> not obviously compromised.
>>
>> 1" is pretty long for a worn brush . . . 1/2"
>> values are quite common. Is that in a 4-pole
>> motor? What are the nameplate sizes for these
>> motors?
>>
>>
>>
>>
>> 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 9
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| Subject: | Re: Any ideas where to get electric motor brushes? |
There is a small one man shop near work who's main business for the last 35
years has been repairing and rebuilding electric motors, generators, and
alternators. Whenever I need brushes, I go to him. If it is automotive,
he looks it up and sells me what I need. If it is not automotive, I bring
him the brushes, and/or the device and he has always been able to come up
with a replacement from his stocks. He told me that brushes come in
different hardnesses. Hard brushes will last a long time, but wear the
slip ring or commutator faster, so you may be in for a ring turning or
replacement eventually. Softer brushes don't last as long, and need
replacement more often, but you will get more ring life out of your device
with them. I usually go softer, since it is much easier to replace several
sets of brushes than dismantle a motor and turn or replace the commutator
once.
My local Home depot also carries a selection of brushes, but you may have
to surreptitiously scratch them to get an idea of their hardness. The
salesmen have no idea. Some large hardware stores also carry a selection
of brushes. If they don't have exactly what you need, they can be filed or
milled to fit.
--Joel
On Sun, Jan 3, 2021 at 11:52 PM rparigoris <rparigor@hotmail.com> wrote:
> rparigor@hotmail.com>
>
> Hi Group
> I need some brushes for the exciter on my Monarch EE lathe. Was making
> some aeroplane parts and it quit.
> Sizes needed:
> 3/8" x 3/8" and worn out length is 1.060", it has a shunt and terminal
> (need 4, will buy 8)
> 1/2" x 1/4" and worn out length is .495", it has a shunt and terminal
> (need 2, will buy 4)
> Any ideas where I can purchase from?
> Thanks
> Ron P.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=499971#499971
>
>
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| Subject: | D-Sub High Density 78 female - solfder or crimp contacts |
Hi Group.
What type contacts would you recommend for a 78 female connector - solder or crimp,
and why?It seems that solder type are easier to find and less expensive.
The connector will be used for a relays box to select VHF nav signals to an HSI.Rumen....
Message 11
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| Subject: | Re: Any ideas where to get electric motor brushes? |
Hi Bob It's for a 1941 Monarch EE. It has a 5HP 3 phase AC motor that spins a 4
pole DC generator, the generator is connected to a 2 pole exciter and the DC
motor is 4 pole. In 1941 they didn't know how to speed control an AC motor so
they did so with a DC motor. I forget exactly the hocus pocus they are doing,
it doesn't have a huge tube, but slow speed torque is quite impressive. I need
exciter and generator brushes and will probably change the motor brushes as well.
All 3 devices have shunt wires. How do I determine what hardness I might
want? The exciter brush has 600 on it. The generator brush has 063A on it. I have
a call into Monarch, but my generator and exciter may not be stock. Thx. Ron
P.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=499998#499998
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| Subject: | Re: Any ideas where to get electric motor brushes? |
At 04:11 PM 1/4/2021, you wrote:
>
>Hi Bob It's for a 1941 Monarch EE. It has a 5HP 3 phase AC motor
>that spins a 4 pole DC generator, the generator is connected to a 2
>pole exciter and the DC motor is 4 pole. In 1941 they didn't know
>how to speed control an AC motor so they did so with a DC motor. I
>forget exactly the hocus pocus they are doing, it doesn't have a
>huge tube, but slow speed torque is quite impressive. I need exciter
>and generator brushes and will probably change the motor brushes as
>well. All 3 devices have shunt wires. How do I determine what
>hardness I might want? The exciter brush has 600 on it. The
>generator brush has 063A on it. I have a call into Monarch, but my
>generator and exciter may not be stock. Thx. Ron P.
Hmmm . . . used to teach those systems at Great
Lakes . . . wish I had the books!
Those number may well be brush grades . . . I've
never worked on motors directly but the gurus were
in the next cubicles . . . and I did a lot of test
instrumentation. So my useful info is limited.
If Monarch can't help, a call to one of the brush specialty
houses may yield some up-to-date expertise. Also,
check around for users/parts manuals. I'm seeing
a lot of offers for used/reproduction on Monarch
manuals.
Do look over the McMaster Carr offerings. Also,
this supplier seems likely to have specialty
expertise.
https://www.graphitestore.com/Carbon-Brushes/Brushes
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 13
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| Subject: | Re: Any ideas where to get electric motor brushes? |
On 1/4/2021 4:11 PM, rparigoris wrote:
>
> Hi Bob It's for a 1941 Monarch EE. It has a 5HP 3 phase AC motor that spins a
4 pole DC generator, the generator is connected to a 2 pole exciter and the DC
motor is 4 pole. In 1941 they didn't know how to speed control an AC motor so
they did so with a DC motor. I forget exactly the hocus pocus they are doing,
it doesn't have a huge tube, but slow speed torque is quite impressive. I need
exciter and generator brushes and will probably change the motor brushes as
well. All 3 devices have shunt wires. How do I determine what hardness I might
want? The exciter brush has 600 on it. The generator brush has 063A on it. I
have a call into Monarch, but my generator and exciter may not be stock. Thx.
Ron P.
>
I'm not Bob, but that sounds like a basic rotary phase converter; still
available to get 3 phase power from 'single phase' service. Might be
branded/made by Monarch, or sourced from a vendor that makes motors &
phase converters. Is the rotary converter built into the lathe, or a
separate component? The ones I've seen are typically separate from the
tool, and often are used to power more than one 3phase tool in the shop
(sometimes one-at-a-time, depending on converter capacity). If it's a
separate component, it should have a dataplate on it somewhere.
FWIW, solid state converters are relatively cheap these days; ex:
https://www.amazon.com/Digital-Phase-Converter-5HP-Range/dp/B07F243HLG/ref=psdc_10967761_t1_B00FF1S5IS
And if you shop around a bit, you can find a 'variable frequency drive'
that will not only give you 3 phase, but the ability to vary the rpm of
the lathe using the converter. Like this:
https://www.amazon.com/Single-Phase-Variable-Frequency-Inverter-Controller/dp/B07L8XZFYG
And no more brush worries (at least in the converter).
Charlie
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| Subject: | D-Sub High Density 78 female - solfder or crimp |
contacts
We generally try to avoid solder cup connectors on aircraft because
typically the average builder doesn=99t have a good high temp yet sma
ll iron
able to successfully use the solder cups (wires often end up cold soldered
and fall off in with future vibration), or they end up wicking tons of
solder up into the wire that inevitably leads to wire breakage.
On top of that, in a 78 pin arrangement the solder cups would be incredibly
densely packed, and it=99s likely the end result would not be pretty.
It also
takes longer than simply crimping on a pin and inserting it into a
connector. Also, if you need to =9Cmove=9D a wire in the middle
of that large
78 pin connector, it=99s pretty easy to do with crimp pins, not so mu
ch with
solder cups.
Lastly, the 78 pin crimp connectors aren=99t that terribly expensive
(we
stock and sell them for about $17 each), standard crimp tooling works well.
Just my 2 cents as usual!
Cheers,
Stein
*From:* owner-aeroelectric-list-server@matronics.com <
owner-aeroelectric-list-server@matronics.com> *On Behalf Of *rd2
*Sent:* Monday, January 4, 2021 3:38 PM
*To:* aeroelectric-list@matronics.com
*Subject:* AeroElectric-List: D-Sub High Density 78 female - solfder or
crimp contacts
Hi Group.
What type contacts would you recommend for a 78 female connector - solder
or crimp, and why?
It seems that solder type are easier to find and less expensive.
The connector will be used for a relays box to select VHF nav signals to an
HSI.
Rumen....
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| Subject: | Re: D-Sub High Density 78 female - solfder or crimp |
contacts
At 03:37 PM 1/4/2021, you wrote:
>Hi Group.
>What type contacts would you recommend for a 78 female connector -
>solder or crimp, and why?
>It seems that solder type are easier to find and less expensive.
>The connector will be used for a relays box to select VHF nav
>signals to an HSI.
>Rumen....
Do you already have the connector to which you want
add wires? How many wires total in your task?
If you're considering a solder style, have you
compared your solder skills and tools with the
sizing of those pins and space between them?
I'm pretty sure that the $savings$ would have
a poor return on investment for the increase in
$time$ and $risk$ unless you're REALLY good
at working with those tiny spaces.
I personally wouldn't take on a soldering task for more
than a handful of wires.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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| Subject: | D-Sub High Density 78 female - solfder or crimp |
contacts
At 04:45 PM 1/4/2021, you wrote:
We generally try to avoid solder cup connectors on aircraft because
typically the average builder doesn't have a good high temp yet small
iron able to successfully use the solder cups (wires often end up
cold soldered and fall off in with future vibration), or they end up
wicking tons of solder up into the wire that inevitably leads to wire breakage.
<snip>
Lastly, the 78 pin crimp connectors aren't that terribly expensive
(we stock and sell them for about $17 each), standard crimp tooling works well.
Just my 2 cents as usual!
More like $20 worth . . . thank you.
Hope you're well and optimistic for
the future my friend. Long time no
talk!
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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| Subject: | Re: Any ideas where to get electric motor brushes? |
Hi Charlie
My Monarch EE helped to win WW2. It was owned by the Singer Corporation until the
1970s. Back in the day, 3 phase AC motors couldn't be speed controlled. Thus
Monarch has an integral 3 phase AC motor with DC Generator. At the tip of the
spinning mass is an Exicter. Some Monarch also used a Magnetron tube. The idea
was you could have a variable speed on the fly with good low speed torque.
If you just cut voltage on a DC motor you can speed control it but low speed torque
suffers. Monarch does some hocus pocus that increases torque at lower speeds
compared to just cutting voltage. DC motor has 4 brushes. Today you have
PWM speed controls for DC motors which can do the same thing, but back then this
was a terrific desirable feature. There are many Monarchs that modify the unit
by removing all this stuff and associated relays and controls and replace
it with a brushless 3 phase AC motor with a speed controller. Not a trivial modification.
I power my stuff with a 7.5hp rotophase running on 220v single phase including
the Monarch.
The main DC motor was rebuilt early on but the Exciter and AC/DC Generator is what
was with machine when purchased from Singer.
I actually have 2 rotophase converters. One 3hp and one 7.5hp. Since the late 1970s
all that I did with the Rotophase converters is put in a tiny amount of grease
and replaced relays and capacitors perhaps once each.
I remember replacing all the brushes in the 1980s when I was using the machine
alot. I goth them from the motor rebuilder. Brushes have lasted till now. Ron
P.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=500005#500005
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| Subject: | Re: Any ideas where to get electric motor brushes? |
Hi Bob Thx. for info. I actually have an inquiry for quote from McMaster. I printed
brush info from graphitestore over the weekend. Minimum of 12 brushes each
buy, would require talking to them about hardness and size of pig tail. One
size only has a spring over pig tail, but could solder on a terminal. I spoke
to a buddy who works for the railroad in the motor rebuilding shop. I'm going
to give him a set of old brushes and he will match em up. He said he's pretty
good determining the hardness of brushes using his precision calibrated "EyeChrometer".
Thx. Ron
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=500006#500006
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| Subject: | Connector advice |
Hey group,
I'm replacing the legacy engine and fuel gauges in my 1978 Cherokee Six
with Mitchell products cluster gauges. The original gauges were fed from a
20AWG wire from a 5A breaker to one of the original gauges and then wired
in series with a jumper wire from gauge to gauge. I need to connect the
original power wire to the power wires of 7 new gauges.I would like a
connector instead of soldering due to the specific requirements I have. Any
recommendations? Cannon plug, molex, dsub? I could go to a bus bar and feed
from there but room is pretty tight under the dash.
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| Subject: | Re: Power-Sonic LiFePO4 (Hypersport) |
>Double the rated total energy sounds like a mislabeled battery.
In my experience, PowerSonic has been
pretty solid in specifying their products.
I would expect some variation of delivered
energy over a spectrum of test loads, but
not by much. LiFePO4 discharge plots are
exceedingly 'flat' with respect to load.
Watt-Hours is a measurement of energy delivered
at the test-value load. This is difficult to measure
without some pretty light footed data recording
techniques. The WestMountain Radio CBA series
battery analyzers are a fine example of low cost,
battery ENERGY measurement tools.
The technique calls for MEASURING load current to
some degree of accuracy (unless you're using a
precision, bench test load) along with battery
voltage.
You measure each value at say, 1 second intervals,
the multiply volts x amps = watts. You now have
a measured packet of energy delivered for a 1-second
interval of time. You SUM that increment to previous
measurements already in storage.
When the test termination voltage is achieved (typically
11.0 volts) then stop the test, add up all the watt-seconds
in storage then divide by 3600 to get watt-hours AT THAT
PARTICULAR TEST CONDITION.
Note that the PC680 is spec'd to deliver 132 WH
for 30 minutes under a 23A load. LiFePO4 with
similar capacity will be in that ballpark.
Note too that as the test current goes DOWN,
the delivered energy goes UP. This is because
less energy is lost to the battery's INTERNAL
RESISTANCE at lighter loads.
A similar thing happens with LiFePO4 but
with less spread across the spectrum of test
loads. This is due to the much lower internal
resistance of the LiFePO4 chemistry. LiFePO4
family of discharge curves are almost coincident.
Your test results suggest a review of test
methodology and instrument capability. I suggest
that the PowerSonic spec sheet is pretty much
gospel. Your bench tests should produce results
pretty close to specs.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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| Subject: | Re: Any ideas where to get electric motor brushes? |
At 07:18 PM 1/4/2021, you wrote:
>
>Hi Charlie
>My Monarch EE helped to win WW2. It was owned by the Singer
>Corporation until the 1970s. Back in the day, 3 phase AC motors
>couldn't be speed controlled. Thus Monarch has an integral 3 phase
>AC motor with DC Generator. At the tip of the spinning mass is an
>Exicter. Some Monarch also used a Magnetron tube. The idea was you
>could have a variable speed on the fly with good low speed torque.
>If you just cut voltage on a DC motor you can speed control it but
>low speed torque suffers. Monarch does some hocus pocus that
>increases torque at lower speeds compared to just cutting voltage.
Actually, not all that mysterious. Railroad locomotives
use a similar technology. Generate power with lots of
volts and current that is hooked to the traction motors
full time. Now, just like the regulator in your car
adjusts power output by modulating FIELD current, the
throttle of a locomotive adjusts field current of a small
exciter which in turn drives the field of the traction
generators which in turn powers the traction motors.
The current being handled by the engineer's throttle
is quite small compared to thousands of amps available
to produce motive power.
In the case of locomotives, they're interested in
traction force which is proportional to motor
current. The electronic controls that watch traction
current to achieve conformity with engineer's throttle
commands operate at relatively low power.
In the lathe case, the goal is to achieve constant
speed as opposed to constant torque. Shuffle the
components in the feedback loop a bit and the
'throttle' now produces a command that the electronics
interprets as a 'speed' requirement as opposed to
'torque'.
The electronics work just like the cruise control
on your car. I.e. adjust manifold pressure (motor
current) as required to achieve constant MPH
(spindle RPM). What ever current it takes to do that
is limited only by capabilities of the power
supply WATTS (gas pedal flat on the floor).
The motor controller in the lathe is oblivious
to present voltage/current as long as physical
limits are not exceeded. BTW, if anyone has a
treadmill, the controller for tread speed is
a direct descendant of the system in the Monarch
lathe except that AC/DC conversion is done with
a rectifier instead of a 3-phase motor generator
set.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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| Subject: | Re: Any ideas where to get electric motor brushes? |
>I power my stuff with a 7.5hp rotophase running on 220v single phase
>including the Monarch.
Okay, if I interpret your words correctly you
use a single-phase to 3-phase external converter
to power the 3-phase to DC motor-generator in
the lathe which includes a low power exciter (generator)
to manage energy delivered to a work-motor that
powers the head-stock?
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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| Subject: | Re: Any ideas where to get electric motor brushes? |
Hi Bob
Exactly correct. The work motor is a 4 brush DC motor, probably ~5hp. I had an
event about 5 years ago, the timing screws loosened up and the thing slid to full
retarded and ripped out a wire. Good thing the wire ripped as running a motor
retarded will trash the armature. I timed motor so it was pretty close to
neutral, perhaps I gave it 1 degree advanced in forward. Has been running great.
To find neutral timing on a motor, you run it forward and reverse and mark
where the current draw is identical. I used about 500 rpm. If running forward
and reverse neutral is best. For best efficiency if only running forward ~ 5 degrees
advanced. Depending on motor, how much heat it can tolerate and how long
you plan to run it hard best power is 7.5 to 15 degrees advanced. Many electric
motors are 5 degrees advanced, don't run them in reverse unless you neutral
time. Ron
Read this topic online here:
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