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Maximum Field Current for Delco 10SI Alternator?
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|
| Ulysses 2008-03-29, 1:25 pm |
| Thanks to many people here I finally understand how to get a 12 volt
alternator to produce over 60 volts! I made a crude field control resistor
from some NiChrome wire and, powered by a 4 HP engine it is doing a fine job
of charging my 48 volt battery bank. I am, however, reluctant to connect
the output of the alternator directly to the field rotor without some
resistance inbetween. Will it damage the field coils if I give it full
power? It stll has the internal, original diodes in there so I'm not going
to try it quite yet in any case. The doides are holding up fine at about 30
amps @ 51 VDC but I suspect they are at their limit. That's about the limit
of 4 HP anyway.
| |
| Martin Riddle 2008-03-29, 1:25 pm |
| I going to guess its around 4amps.
Is the 10si a 60 or 100amp animal?
Cheers
"Ulysses" <eatmyspam@spamola.com/> wrote in message news:FgtHj.10794$Ro1.9245@fe091.usenetserver.com...
> Thanks to many people here I finally understand how to get a 12 volt
> alternator to produce over 60 volts! I made a crude field control resistor
> from some NiChrome wire and, powered by a 4 HP engine it is doing a fine job
> of charging my 48 volt battery bank. I am, however, reluctant to connect
> the output of the alternator directly to the field rotor without some
> resistance inbetween. Will it damage the field coils if I give it full
> power? It stll has the internal, original diodes in there so I'm not going
> to try it quite yet in any case. The doides are holding up fine at about 30
> amps @ 51 VDC but I suspect they are at their limit. That's about the limit
> of 4 HP anyway.
>
>
| |
| Don Young 2008-03-29, 8:25 pm |
|
"Ulysses" <eatmyspam@spamola.com/> wrote in message
news:FgtHj.10794$Ro1.9245@fe091.usenetserver.com...
> Thanks to many people here I finally understand how to get a 12 volt
> alternator to produce over 60 volts! I made a crude field control
> resistor
> from some NiChrome wire and, powered by a 4 HP engine it is doing a fine
> job
> of charging my 48 volt battery bank. I am, however, reluctant to connect
> the output of the alternator directly to the field rotor without some
> resistance inbetween. Will it damage the field coils if I give it full
> power? It stll has the internal, original diodes in there so I'm not
> going
> to try it quite yet in any case. The doides are holding up fine at about
> 30
> amps @ 51 VDC but I suspect they are at their limit. That's about the
> limit
> of 4 HP anyway.
>
>
I do not know the ratings or limits but these alternators have been adapted
successfully in cars and trucks to generate 120 VDC for power tools. I seem
to remember that the field was supplied directly from the 12V car battery.
Somewhere I have an adapter box sold commercially for this purpose.
Don Young
| |
| clare at snyder dot ontario dot canada 2008-03-29, 9:25 pm |
| On Sat, 29 Mar 2008 20:23:09 -0500, "Don Young" <notme@nonesuch.com>
wrote:
[color=darkred]
>
BEL electronics used to make an adapter box that ran 12 volts to the
feild and controlled voltage with the throttle (manually) MOST
alternator diodes are 250PIV or better
--
Posted via a free Usenet account from http://www.teranews.com
| |
| Whata Fool 2008-03-30, 3:25 am |
| "Ulysses" <eatmyspam@spamola.com/> wrote:
>Thanks to many people here I finally understand how to get a 12 volt
>alternator to produce over 60 volts! I made a crude field control resistor
>from some NiChrome wire and, powered by a 4 HP engine it is doing a fine job
>of charging my 48 volt battery bank. I am, however, reluctant to connect
>the output of the alternator directly to the field rotor without some
>resistance inbetween. Will it damage the field coils if I give it full
>power?
Yes it will, don't do that! The field coils are
12 volts, period. They will take the usual charging
voltage of 14.6 to 15.1 or so, but more than that will
burn them out.
Resistance loads draw amperage according to the
voltage applied and their resistance, higher voltage
devices need higher resistance to avoid burning out.
>It stll has the internal, original diodes in there so I'm not going
>to try it quite yet in any case. The doides are holding up fine at about 30
>amps @ 51 VDC but I suspect they are at their limit. That's about the limit
>of 4 HP anyway.
A separate 12 volt battery should be used to
supply field current with any abnormal use such as
this, but the output capability is more related to
the insulation rating as long as the output amps is not
exceeded.
A small 60 amp alternator can go to 110 volts
output (probably), but for charging batteries, the
voltage loaded should not go more than a couple
of volts over the battery rating.
And the amps should be restricted to the rating
of the alternator. Some big GM cars came with 100 amp
alternators, possibly as an option or certain models.
But a 12 volt alternator has 12 volt field coils,
and most alternators on US cars have small brushes
that have to carry the current to the rotating field,
and higher voltage will burn out the field coils and
damage the brush connections too.
| |
| Neon John 2008-03-30, 3:25 am |
| On Sat, 29 Mar 2008 23:36:47 -0500, Whata Fool <whata@fool.ami> wrote:
>"Ulysses" <eatmyspam@spamola.com/> wrote:
>
>
> Yes it will, don't do that! The field coils are
>12 volts, period. They will take the usual charging
>voltage of 14.6 to 15.1 or so, but more than that will
>burn them out.
Actually, no it isn't. The only practical limitation is temperature and in the case
of automotive alternators, the insulation is high temperature rated, class H or
above. Like your handle. Apropos.
Ulysses:
The correct answer is, "I don't know". You'll have to monitor the temperature of the
field coil as you increase the current. If you're clever you can use the field's
resistance to measure the temperature. I'll describe how if you're interested. The
cooler the operating environment and the higher the air flow, the more field current
you can run.
I'm interested to hear what is in Don Young's adapter box. I've used power from one
of these gadgets before but I've never had one open. Meanwhile, through the magic of
Google, I found some info. I searched for "120 volts DC car alternator kit
-converter -inverter" without the quotes. The first useful hit is this
http://islandcastaway.com/stuff/win...r%20Secrets.htm
Go down to "Modifications". He purports to knowing what is inside the magic box.
OTOH, I quickly spotted other mistakes on the page so.... That was all I found on
the first 100 results but there is probably more info deeper down.
RE: diode voltage rating. What someone else said about the voltage rating of the
alternator's diodes was true in the past but isn't now and hasn't been for several
years. With the inclusion of more solid state controls and especially
microprocessor-based controls, two problems had to be addressed. 1) EMI caused by
the abrupt recovery and turn-off of the alternator diodes on each half-cycle and 2)
load dumps. That is, high energy high voltage impulses caused by suddenly
interrupting the current to an inductor. Typically the alternator field and the
starter motor.
A voltage spike caused by a load dump didn't matter much pre-microprocessor. About
all one saw was a momentary brightening of various lamps. Nowadays it does matter.
The industry (for sure GM and Ford and probably everyone else) addressed both of
these problems with a new design diode. It's called a soft recovery diode. When the
voltage across the diode reverses on each half-cycle, it transitions gradually from
conducting to blocking, minimizing the EMI generated.
Another engineered feature of this diode is the low peak inverse voltage rating. It
is designed to conduct at a relatively low reverse voltage. An SAE standard calls
for no more than 60 volts to ever appear on the 12 volt supply so the diode probably
conducts (zeners) below that. This conduction clamps load dumps to no more than the
avalanche (zener) voltage.
Bottom line: alternators with soft recovery rectifiers will not work for high voltage
generation. Which ones have these diodes? Got me. But it would be a safe bet to
regard any alternator 15 or less years old to have 'em until proved otherwise. I
know for a fact that the old large body Mopar alternators and the first and second
gen GM alternators do NOT have soft recovery diodes. The alternator on my 94 Caprice
does. The safest plan would be to use external general purpose rectifiers.
Here are a couple of data points on alternator field excitation. The first gen Mopar
large frame alternator on my 68 Fury had 6-9 volts on the field for 14 volts out at
idle. The GM/caddy alternator that I use on my CBC has 6-8 volts on the field,
depending on load, running at about 3,000 RPM.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Save a tree, kill a beaver
| |
| Whata Fool 2008-03-30, 9:25 am |
| Neon John <no@never.com> wrote:
>On Sat, 29 Mar 2008 23:36:47 -0500, Whata Fool <whata@fool.ami> wrote:
>
>
>Actually, no it isn't. The only practical limitation is temperature and in the case
>of automotive alternators, the insulation is high temperature rated, class H or
>above. Like your handle. Apropos.
It will only cost about $50 or less to find out,
but consider the field coil to be like a light bulb,
a higher voltage than rated will blow it out instantly.
Perhaps if the alternator were turning fast
enough there would be enough counterelectromotive
force to limit current, but current in the field
of an alternator is a function of voltage, at least
at low RPM.
The fact that 12 volts is enough to fully
excite the field to produce the full rated amps
of the alternator means there is no need to ever
exceed the 12 volts (provided the RPM is high enough).
And being this is a rectified AC induction machine,
I think energy increases both with RPM and cycles
ahead of the diodes, faster cycles increases energy
output non-linearily.
I had a 6 volt alternator off a police car
and put it on my 1949 Buick Roadmaster convertible
(in 1956) and a 120 Volt step up transformer came
with it.
I could run a 120 volt AC TV with it, but
it was obvious the cycles caused power to increase
faster than voltage because the 3-phase AC leads
came out to the transformer and the huge selenium
rectifier bank (bigger than a breadbox), and after
a few days I burned out the tubes in the TV.
An alternator running without a voltage
regulator with field current supplied by the
alternator will be open ended on voltage if
the load is not enough to hold the voltage down.
Batteries do provide a lot of load as RPM
increases, but voltage still needs to be controlled
either with RPM or voltage regulation of field.
>Ulysses:
>
>The correct answer is, "I don't know". You'll have to monitor the temperature of the
>field coil as you increase the current. If you're clever you can use the field's
>resistance to measure the temperature. I'll describe how if you're interested. The
>cooler the operating environment and the higher the air flow, the more field current
>you can run.
>
>I'm interested to hear what is in Don Young's adapter box. I've used power from one
>of these gadgets before but I've never had one open. Meanwhile, through the magic of
>Google, I found some info. I searched for "120 volts DC car alternator kit
>-converter -inverter" without the quotes. The first useful hit is this
>
>http://islandcastaway.com/stuff/win...r%20Secrets.htm
>
>Go down to "Modifications". He purports to knowing what is inside the magic box.
>OTOH, I quickly spotted other mistakes on the page so.... That was all I found on
>the first 100 results but there is probably more info deeper down.
The details of the "magic box" are essentially correct,
nothing more than a double pole, double throw 30 AMP switch,
in a metal utility box with a duplex receptacle.
Power tools (that have brushes) are AC-DC, so as long
as voltage is not too high or too low, they work ok.
But he does mention there is no alternator output
to the battery with the "magic box", obviously that is
what the second set of contacts do, disconnect the battery
from the alternator output.
It would be nice to be able to run two alternators,
one for 12 volts to the battery, and one for 120 volts,
but the fact that RPM is the only voltage control with
the "magic box", even that isn't an option, the "magic box"
can only be used when the engine is run at constant RPM
like with a hand throttle (old cars had them), so the
car can't be driven while using it.
>[snip]
>Here are a couple of data points on alternator field excitation. The first gen Mopar
>large frame alternator on my 68 Fury had 6-9 volts on the field for 14 volts out at
>idle. The GM/caddy alternator that I use on my CBC has 6-8 volts on the field,
>depending on load, running at about 3,000 RPM.
>
>John
A simple variable resistor could be used to
control field voltage if one can be found that can
carry field current, but simple things only work
for certain uses.
It shouldn't be too difficult to build a
voltage regulator with silicon controlled rectifiers,
they are used to control motor speed on strip mine
drag line DC motors running right off a 4 inch diameter
extension cord from the power grid at 2200 volts.
But the work and expense for that might exceed
the need for the power use, unless somebody makes
them ready made at a reasonable cost.
Obviously these types of devices are available,
but the economics have to make sense.
Note that the "magic boxes" were in most auto
supply stores in the late 1950s, '60s and '70s,
but they are too simple to construct to bother
shopping for one.
Warning: Some 12 volt car batteries have
small lead connectors internally and a short can
melt them and the arc can cause the hydrogen in
the battery to explode (I only saw this once,
thankfully nobody was close without eye protection).
There really needs to be more DIY effort with
power systems, not only for home power, but the
only way that gas mileage can be increased is with
Electric Vehicles.
For some reason the auto makers are stalling
on going to a simple Plugin-Hybrid Electric Vehicle,
and a grass roots effort could force that to change,
only 20 HP is needed to keep the batteries charged
for driving at 50 MPH (on level ground).
I would opt for two 20 HP generators, and only
run the second for hills, and have the redundancy
in case one fails.
Small power machines would have a much larger
market and be more useful if more hardware was
available for DIY.
| |
| Vaughn Simon 2008-03-30, 9:25 am |
|
"Neon John" <no@never.com> wrote in message
news:ed5uu3dnnn2d5h1ibcuh3c08v3no00sqes@4ax.com...
> On Sat, 29 Mar 2008 23:36:47 -0500, Whata Fool <whata@fool.ami> wrote:
> I'm interested to hear what is in Don Young's adapter box. I've used power
> from one
> of these gadgets before but I've never had one open.
We bought one of those boxes 25 years ago for one of our service trucks. The
best answer to your question is "nothing but a big switch" The switch
disconnected the alternator from the truck's DC buss and simultaneously bypassed
the regulator. I don't know if we actually got 120 volts out, but it was
enough to run an electric drill in occasional service. Back then, most of our
trucks either had fanbelt-driven AC generators or 12 VDC/120 VAC MG sets.
Vaughn
| |
| JimG64155 2008-03-30, 1:25 pm |
| On Mar 30, 8:27=A0am, "Vaughn Simon" <vaughnsimonHATESS...@att.FAKE.net>
wrote:
> "Neon John" <n...@never.com> wrote in message
>
> news:ed5uu3dnnn2d5h1ibcuh3c08v3no00sqes@4ax.com...
My Dad made these kind of conversion kits in the 60's. They consisted
of a double pole switch that bypassed the regulator, connecting the
battery directly to the rotor circuit of the alternaltor. The output
was a variable 100 to 130 volts (or so) DC, at about 30 amps,
depending on engine rpm and load.
He used them for powering portable tools and lights on job sites. He
said he jump started semi trucks with them also.
One limitation was that the switch must be done with the vehicle off
to prevent blowing the diodes in the alternator. The system also had
to be shut down periodically and switched back to normal operation to
recharge the vehicle battery.
Jim
| |
| Neon John 2008-03-30, 5:25 pm |
| On Sun, 30 Mar 2008 06:26:19 -0500, Whata Fool <whata@fool.ami> wrote:
>
> It will only cost about $50 or less to find out,
>but consider the field coil to be like a light bulb,
>a higher voltage than rated will blow it out instantly.
Wrong again. Twice, actually. An alternator field is not like a light bulb at all,
in that it is not designed to produce heat. And a light bulb doesn't "blow out
instantly" when over-voltaged. Many years ago Westinghouse researchers developed a
heuristic for bulb life vs voltage. Life varies as the thirteenth power of voltage
deviation from the nominal. You picks your voltage and you lives with the life. Or
you picks your life and live with the light output.
In my little photography studio, I run ordinary 120 volt, 500 watt quartz-halogen
lamps on 240 volts. The output is dazzling and is just the right color temperature
for tungsten-balanced film. The filament gets hot enough to bulge the quartz between
filament supports but in several years of use, I've only had a couple of lamp
failures, in sharp contrast to photoflood lamps.
Back to alternator fields. What I said before stands. One can apply whatever
current he desires as long as the temperature limits of the insulation are observed.
Operating in free air, as opposed to under the hood, one has plenty of margin to
experiment with.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Some people are like a Slinky .. not really good for anything
but you still smile
when you shove them down the stairs.
| |
| nicksanspam@ece.villanova.edu 2008-03-30, 5:25 pm |
| Neon John <no@never.com> wrote:
>... Many years ago Westinghouse researchers developed a heuristic for
>bulb life vs voltage. Life varies as the thirteenth power of voltage
>deviation from the nominal.
So a 120V 1000 hour bulb run at 240V would last 1000/(2^13) = 0.12 hours?
>... I run ordinary 120 volt, 500 watt quartz-halogen lamps on 240 volts.
>The output is dazzling
For how long? :-)
Nick
| |
| Neon John 2008-03-30, 8:25 pm |
| On 30 Mar 2008 16:32:31 -0500, nicksanspam@ece.villanova.edu wrote:
>Neon John <no@never.com> wrote:
>
>
>So a 120V 1000 hour bulb run at 240V would last 1000/(2^13) = 0.12 hours?
Maybe, if the voltage is brought up slowly or unless it instaflashes. OTOH, since a
regular household runs at a fairly high temperature already for good color rendering
and since it has a short design light, maybe not. Run the lamp at 130 or 140 volts
and see how it conforms to Westinghouse's heuristic.
If you're actually interested in how incandescent lamps behave at overvoltage (I
suspect you're not and that you're just being your usual chickensh*t self but just in
case anyone else is), go to http://www.candlepowerforums.com and look for a member
called Luxluthor. He's done a very extensive several year study of mostly portable
lighting-related lamps operated on over-voltage. He includes performance curves and
instaflash voltages. His work includes many small low voltage high wattage
quartz-halogen lamps, typically AV lamps.
Many lamps will go 3X nominal voltage before instaflashing. Many of those will
operate for satisfactory time periods at the instaflash voltage if brought up slowly,
as with a PWM controller.
>
>
>For how long? :-)
Probably 20 to 30 hours on mine. I've had 2 or 3 fail but all those failures were
infant mortalities. Once the lamp gets past the first few minutes of operation, it
is good for many hours. I use those cheap chicom "5 for $5" harbor freight special
lamps. they've turned out to last as long as brand name ones.
I bring the lamps up on about 145 volts (variac-controlled) for modeling and framing.
I have a push button on a cord that I press just before the exposure. The button
operates a contactor that switches to the full 240 volts. They stay at that power
only long enough to meter the light, set the exposure and take the picture.
If you're interested in the details - again, I'm sure you're not - then you can look
around the net for an article I wrote several years ago for a glass art newsletter.
It was a paper publication then but I'm sure it's online by now.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
It isn't Global Warming.... It's Jerry Falwell arriving in hell.
| |
| clare at snyder dot ontario dot canada 2008-03-30, 8:25 pm |
| On Sun, 30 Mar 2008 18:55:10 -0400, Neon John <no@never.com> wrote:
[color=darkred]
>
>Many lamps will go 3X nominal voltage before instaflashing. Many of those will
>operate for satisfactory time periods at the instaflash voltage if brought up slowly,
>as with a PWM controller.
>
If I remember properly from years back, Tungsten Halogen (or metal
halide) bulbs behave differently than standard incandescents due to
the "halide cycle". Tun at too low a voltage the tungsten boils off
and does not form a proper metal halide and does not redeposit on the
filament, causing severely shortened lamp life at moderate
undervoltage. Moderate overvoltage has much less effect , from what I
remember. Big problem with overvoltage on halides is from reduced
filament durability - so vibration and shock kill halide bulbs faster
when moderately overvoltage. This is why low voltage halogens stand up
better - as they have a heavier (higher current meand thicker
fillament) tungsten fillament than high votage bulbs, so they are
physically more robust.
Again, it's been 35+ years since I worked with the AV stuff on a daily
basis, and the halide bulbs were pretty new tech back then - and I've
forgotten a lot
--
Posted via a free Usenet account from http://www.teranews.com
| |
| nicksanspam@ece.villanova.edu 2008-03-31, 3:25 am |
| Neon John <no@never.com> wrote:
>
>Maybe, if the voltage is brought up slowly...
[color=darkred]
>Probably 20 to 30 hours on mine.
Interesting. Don Klipstein says:
>...bulb life is typically inversely proportional to applied voltage
>raised to the 12th power. I often see 13.
So if a 120 V bulb lasts 750 hours at 120V, Don might expect it to last
(120/240)^12x750 = 0.18 hours (11 minutes) at 240V.
Nick
| |
| Neon John 2008-03-31, 3:25 am |
| On 30 Mar 2008 22:54:16 -0500, nicksanspam@ece.villanova.edu wrote:
>Neon John <no@never.com> wrote:
>
>
>Interesting.
Only to folks like you who know just enough about a subject to argue. The original
paper, a copy of which I have, addresses only conventional tungsten lamps. I'm not
sure if the halogen cycle had been discovered at the time of publication.
I'm curious whether you'd find it equally interesting to note that a 4 hour
photoflood lamp and a quartz heat lamp designed to operate at maybe 2000 deg K behave
quite differently in response to over-voltage? Kinda Captain Obvious to me. It
would probably surprise you to learn that a staple of the studio in the bad old days
was the Sola transformer that made sure the photofloods were getting their exact
rated voltage while no one seems to care much about heat lamps.
>Don Klipstein says:
>
I probably need to send Don a copy of the paper. Don's a collator of information so
he publishes only what he's found elsewhere. He doesn't do original research. 12
and 13 seem to be bandied about the net about equally but the original paper says 13.
Here's a page referencing GE's heuristic. You might notice that GE's exponent is
13.1 for gas-filled and 13.5 for vacuum.
http://www.zap-tek.com/webpage/Elec...4_lamp_res.html
Can I please, mas'a Nick, champion of all nitpickers, be permitted to round 13.1 to
13 for the purposes of idle conversation?
OTOH, the nomograph (by any chance know how to use one of those, Nick?) here seems to
be using exp 12.
http://www.squidoo.com/tungstenlamps
A master nitpicker might also notice that Squidoo claims that the same exponent
applies to all lamp types while the GE heuristic shows different exponents and the
Westinghouse paper addresses only "incandescent" lamps, presumably nitrogen-filled,
given the vintage.
I'm sure you'd agree with me, nick, that none of this has any relevance at all to the
question of whether an alternator field coil in any way behaves like an incandescent
lamp.
[color=darkred]
>So if a 120 V bulb lasts 750 hours at 120V, Don might expect it to last
>(120/240)^12x750 = 0.18 hours (11 minutes) at 240V.
BSIBSO (Nick's version of GIGO, BS in/BS out). Or what happens when one knows just
enough to do the math but not enough to apply the data. Hint: You might note in the
URL above that the GE heuristic is useful for no more than +-10% from the nominal.
BTW, any particular reason you chose 750 hours this time and 1000 hours on the last
round? Just pullin' numbers out of yer nether region again?
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Save the whales, collect the whole set!
| |
| nicksanspam@ece.villanova.edu 2008-03-31, 9:25 am |
| Neon John <no@never.com> wrote:
>
>Only to folks like you who know just enough about a subject to argue.
Noticing apparent contradictions is one way to learn.
>I'm curious whether you'd find it equally interesting to note that a 4 hour
>photoflood lamp and a quartz heat lamp designed to operate at maybe 2000 deg K
>behave quite differently in response to over-voltage?
Less so, since those are less common in houses.
>Can I please, mas'a Nick, champion of all nitpickers, be permitted to round
>13.1 to 13 for the purposes of idle conversation?
Of course. My friend Drew Gillett often rounds 60 to 100 :-)
>
>BTW, any particular reason you chose 750 hours this time and 1000 hours
>on the last round?
Just recalling an earlier posting...
Article 128163 of alt.energy.homepower:
From: nicksanspam@ece.villanova.edu
Subject: Re: convert heater 110 to230??
Date: 17 Jul 2007 18:36:55 -0400
Organization: Villanova University
Neon John <no@never.com> wrote:
>... I'm standing here looking at a 100 watt lightbulb running through a 1N4005
>that I had handy, connected to a 240 volt heater outlet through a Jesus Cord.
>Just as the *proper* math predicts, the bulb is burning at half brightness -
>1/4 the power it would receive on 240.
Curious. If 240 is the rms value of a 240 volt waveform, ie the square root
of the sum of the squares of instantaneous values over 1 positive cycle and
1 negative cycle, divided by the full cycle time, the sum itself is 240^2
= 57,000 V^2, no? If we eliminate one of the 2 cycles, the sum is 57,000/2
= 28,800 V^2, and the square root of that (the rms voltage of the half-wave
rectified waveform) is 170 vs 120 V.
Don Klipstein says:
>...bulb life is typically inversely proportional to applied voltage
>raised to the 12th power. I often see 13.
So if a 120 V bulb lasts 750 hours at Vrms = 120, we might expect it
to last (120/170)^12x750 = 11.5 hours at 170 Vrms.
If we eliminate 3 out of 4 half-cycles, the sum becomes 14,400 V^2,
and the square root of that is 120 Vrms...
Nick
| |
| Whata Fool 2008-03-31, 9:25 am |
| Neon John <no@never.com> wrote:
>On 30 Mar 2008 22:54:16 -0500, nicksanspam@ece.villanova.edu wrote:
>
>
>Only to folks like you who know just enough about a subject to argue.
I find it bizarre that anyone would spread information
that encourages pushing the envelope, totally without reason,
while you seem to be fixated on getting the most light out
of one lamp when two would do the job, just so you can use
a smaller lens opening and get everything in better focus.
While you are right about a resistance device only
failing when current is excessive, but the fact is,
current increases with the square of the voltage.
Short time overvoltage may work in some cases,
which is why motors are rated short duty and continuous
duty. A generator needs to be fully continuous duty,
so that current overheating is not a problem.
Are you willing to pay for the bulbs and field
coils that people burn out using your advice.
Good engineering means a safety factor of 2 or more,
and even with all the engineering to get the best light
possible out of common bulbs, they burn out often with
just minor voltage pulses from motors starting, and that
is I buy 130 volt bulbs, there is more to bulbs burning
out than cost.
| |
|
|
"Whata Fool" <whata@fool.ami> wrote in message
> While you are right about a resistance device only
> failing when current is excessive, but the fact is,
> current increases with the square of the voltage.
Power increases with the square of the voltage. Current increases with the
voltage. Double the voltage double the current.
| |
| Ulysses 2008-03-31, 1:25 pm |
|
"Whata Fool" <whata@fool.ami> wrote in message
news:uak1v39l3a5arquveh63iops6qcd3va3of@4ax.com...
> Neon John <no@never.com> wrote:
>
>
> I find it bizarre that anyone would spread information
> that encourages pushing the envelope, totally without reason,
> while you seem to be fixated on getting the most light out
> of one lamp when two would do the job, just so you can use
> a smaller lens opening and get everything in better focus.
I believe the reason he is running them at the higher voltage is to obtain
the correct color temperature.
[color=darkred]
| |
| Ulysses 2008-03-31, 1:25 pm |
|
"Martin Riddle" <martin_rid@verizon.net> wrote in message
news:_FuHj.2257$gS1.1768@trndny07...
> I going to guess its around 4amps.
> Is the 10si a 60 or 100amp animal?
It's the 60 amp (I think it's rated at 63 amps) critter.
>
> Cheers
> "Ulysses" <eatmyspam@spamola.com/> wrote in message
news:FgtHj.10794$Ro1.9245@fe091.usenetserver.com...
resistor[color=darkred]
job[color=darkred]
connect[color=darkred]
going[color=darkred]
about 30[color=darkred]
limit[color=darkred]
>
>
| |
| nicksanspam@ece.villanova.edu 2008-03-31, 1:25 pm |
| Whata Fool <whata@fool.ami> wrote:
> While you are right about a resistance device only
>failing when current is excessive, but the fact is,
>current increases with the square of the voltage.
Really? :-)
Nick
| |
| Whata Fool 2008-03-31, 1:25 pm |
| nicksanspam@ece.villanova.edu wrote:
>Whata Fool <whata@fool.ami> wrote:
>
>
>Really? :-)
>
>Nick
Excuse the terminology, I have replaced
a lot of hot plate and oven elements with element
wire without any documentation.
The amps for a 100 watt device might be
1 Amp on 110, and 2.18 on 240, but watts is
the heating factor, doesn't that add up to
4 times the heat?
The formulas are usually not expressed
as I used them, I had to use volts * volts
to determine the resistance, the wire came
in various ohms per foot.
| |
| Neon John 2008-03-31, 8:25 pm |
| On Mon, 31 Mar 2008 07:33:36 -0800, "Ulysses" <eatmyspam@spamola.com/> wrote:
>
>I believe the reason he is running them at the higher voltage is to obtain
>the correct color temperature.
Shhhhh! Don't let the secret out.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Unable to locate Coffee -- Operator Halted!
| |
| Martin Riddle 2008-03-31, 8:25 pm |
|
"Ulysses" <eatmyspam@spamola.com/> wrote in message news:5u7Ij.22811$wn3.17351@fe115.usenetserver.com...[color=darkred]
>
> "Martin Riddle" <martin_rid@verizon.net> wrote in message
> news:_FuHj.2257$gS1.1768@trndny07...
>
> It's the 60 amp (I think it's rated at 63 amps) critter.
>
Yea, it seems to be around 5-6amp for full output, 65amp. My CS-130 (100amp) requires 10 amp on the field for 100A out. Thus
90% of the output is produced by mechanical energy.
Hope that helps.
Cheers
| |
| Johnny B Good 2008-03-31, 8:25 pm |
| The message <uak1v39l3a5arquveh63iops6qcd3va3of@4ax.com>
from Whata Fool <whata@fool.ami> contains these words:
> Neon John <no@never.com> wrote:
[color=darkred]
> I find it bizarre that anyone would spread information
> that encourages pushing the envelope, totally without reason,
> while you seem to be fixated on getting the most light out
> of one lamp when two would do the job, just so you can use
> a smaller lens opening and get everything in better focus.
> While you are right about a resistance device only
> failing when current is excessive, but the fact is,
> current increases with the square of the voltage.
You're confusing ohm's law with the power law. Ignoring changes of
resistance due to temperature, the current is directly in proportion to
the voltage. It is power which is proportional to the square of the
voltage (or current, take your pick).
> Short time overvoltage may work in some cases,
> which is why motors are rated short duty and continuous
> duty. A generator needs to be fully continuous duty,
> so that current overheating is not a problem.
> Are you willing to pay for the bulbs and field
> coils that people burn out using your advice.
> Good engineering means a safety factor of 2 or more,
> and even with all the engineering to get the best light
> possible out of common bulbs, they burn out often with
> just minor voltage pulses from motors starting, and that
> is I buy 130 volt bulbs, there is more to bulbs burning
> out than cost.
FYI, regarding metal halide lamps, the use of a halide and a high
temperature envelope in close proximity to the filament is not to make
the filament last longer at elevated temperature, it's to allow the lamp
to maintain its lumen output over its shortened lifetime by recycling
the tungsten vapour back onto the filament to save it from depositing on
the envelope and acting as a light blocking filter.
The tungsten halide cycle relies upon the envelope operating at much
higher temperatures than possible with conventional glass to prevent the
deposition of tungsten on the inner surface. The silicate glass used
(the so called "Quartz Glass") usually operates at temperatures between
250 and 300 deg C. If you undervolt such a lamp, the cooler temperature
on the envelope will compromise this effect and, although the filament
life will be extended, the envelope will suffer blackening and reduce
the lumen output.
The reason why the tungsten halide cycle doesn't improve the filament
life is because the tungsten vapour is deposited onto the cooler parts
of the filament and its supports. The hotter parts of the filament still
erode in pretty much the same way as in an ordinary vacuum or nitrogen
filled lamp. This erosion thins the filament causing it to run even
hotter in what is basically a runaway process.
This wear mechanism is further agravated by the high current surge when
such lamps are switched on from cold (cold filament resistance being
only about one tenth of the operating temperature resistance). Since the
ever so slightly to start with thinner parts of the filament heat up
faster than the remaining thicker parts of the filament and to a
slightly higher temperature than normal, the thinner parts suffer more
loss of tungsten until they either fail at the next switch on (the usual
fate for a household lamp) or else fail several hours after the fatal
switch on event.
Such "Thousand Hour" lamps can survive several thousands of hours, if
left burning continuously and not subjected to switch on surges such
lamps usually have to contend with in a normal domestic service
environment.
Regarding the maximum field current question, there is no point in
allowing more current than the maximum based on the 12 volt excitation
voltage since this will have been set, by design, for magnetic
saturation or very close to. Additional current over and above this will
produce very little extra magnetic flux but considerably more heat.
Also, since this waste heat is a drain of power from the alternator's
output, the overall efficiency will be significantly reduced.
I seem to recall a maximum excitation current figure of 4 amps for a
12v alternator. If such an alternator's voltage regulator were to be
reconfigured to charge a "60 volt" lead acid battery and permitted to
apply the full output voltage to the field, you could end up raising the
excitation losses from about 50 watts to some 800 watts or more!
Basically, there's no simple solution to this "problem" (there _are_
solutions, but no simple ones).
HTH & HAND
--
Regards, John.
Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.
| |
| clare at snyder dot ontario dot canada 2008-04-01, 3:25 am |
| On Mon, 31 Mar 2008 00:41:36 -0400, Neon John <no@never.com> wrote:
>On 30 Mar 2008 22:54:16 -0500, nicksanspam@ece.villanova.edu wrote:
>
>
>Only to folks like you who know just enough about a subject to argue. The original
>paper, a copy of which I have, addresses only conventional tungsten lamps. I'm not
>sure if the halogen cycle had been discovered at the time of publication.
>
>I'm curious whether you'd find it equally interesting to note that a 4 hour
>photoflood lamp and a quartz heat lamp designed to operate at maybe 2000 deg K behave
>quite differently in response to over-voltage? Kinda Captain Obvious to me. It
>would probably surprise you to learn that a staple of the studio in the bad old days
>was the Sola transformer that made sure the photofloods were getting their exact
>rated voltage while no one seems to care much about heat lamps.
>
PhotoFloods are basically the same as an overvoltaged standard
incandescent to start with. VERY fine filaments, extremely shock
intolerant. A 4 hour photoflood is running very close to it's
self-destruct level in everyday use, while the heat lamp is running
closer to the low end of it's envelope.
>
>I probably need to send Don a copy of the paper. Don's a collator of information so
>he publishes only what he's found elsewhere. He doesn't do original research. 12
>and 13 seem to be bandied about the net about equally but the original paper says 13.
>
>Here's a page referencing GE's heuristic. You might notice that GE's exponent is
>13.1 for gas-filled and 13.5 for vacuum.
>
>http://www.zap-tek.com/webpage/Elec...4_lamp_res.html
>
>Can I please, mas'a Nick, champion of all nitpickers, be permitted to round 13.1 to
>13 for the purposes of idle conversation?
>
>OTOH, the nomograph (by any chance know how to use one of those, Nick?) here seems to
>be using exp 12.
>
>http://www.squidoo.com/tungstenlamps
>
>A master nitpicker might also notice that Squidoo claims that the same exponent
>applies to all lamp types while the GE heuristic shows different exponents and the
>Westinghouse paper addresses only "incandescent" lamps, presumably nitrogen-filled,
>given the vintage.
>
>I'm sure you'd agree with me, nick, that none of this has any relevance at all to the
>question of whether an alternator field coil in any way behaves like an incandescent
>lamp.
>
>
>
>BSIBSO (Nick's version of GIGO, BS in/BS out). Or what happens when one knows just
>enough to do the math but not enough to apply the data. Hint: You might note in the
>URL above that the GE heuristic is useful for no more than +-10% from the nominal.
>
>BTW, any particular reason you chose 750 hours this time and 1000 hours on the last
>round? Just pullin' numbers out of yer nether region again?
>
>John
--
Posted via a free Usenet account from http://www.teranews.com
| |
| Ulysses 2008-04-01, 1:25 pm |
|
"Whata Fool" <whata@fool.ami> wrote in message
news:d25uu35rbmdilth89pmgj2v5m6mp3itsv4@4ax.com...
> "Ulysses" <eatmyspam@spamola.com/> wrote:
>
resistor[color=darkred]
job[color=darkred]
>
> Yes it will, don't do that! The field coils are
> 12 volts, period. They will take the usual charging
> voltage of 14.6 to 15.1 or so, but more than that will
> burn them out.
>
I measured 13.5 volts going to the field coil so it's looks like I'm right
where I should be.
> Resistance loads draw amperage according to the
> voltage applied and their resistance, higher voltage
> devices need higher resistance to avoid burning out.
>
30[color=darkred]
limit[color=darkred]
>
> A separate 12 volt battery should be used to
> supply field current with any abnormal use such as
> this, but the output capability is more related to
> the insulation rating as long as the output amps is not
> exceeded.
That is beginning to sound complicated. I could tap into two batteries on
my battery bank and they in turn would be charged by the alternator that
they would be supplying the field current for but something tells me this is
a bad idea. How would you suggest recharging the seperate 12 volt battery?
>
> A small 60 amp alternator can go to 110 volts
> output (probably), but for charging batteries, the
> voltage loaded should not go more than a couple
> of volts over the battery rating.
The way I see it I have three choices with this setup:
1. Adjust the field current and engine speed so that it will put out the
correct Absorb Voltage with no load and go manually check it once-in-a-while
and turn it off when the batteries are fully charged. This takes a long
time.
2. Feed the output from the alternator into my OutBack MX60 charge
controller and let it adjust the voltage and current. This works well but
will not stop charging when the batteries are charged and if there's an AUX
setting that will turn off the charger I have not found it yet. When it
goes into "Sweep" mode it will (sometimes) stop charging for about a minute.
I takes (sometimes) up to about five minutes for it so wake up from it's
"sleeping" mode when I first start the charger. Meanwhile the engine is
running at full RPM with no load.
3. Adjust the engine speed and field current for what "feels" best, IOW
reduce the engine speed until the amps just start to drop a little. With
this arangement the Voc is about 80 VDC. I connected a 12 volt relay and
set the AUX on my OutBack inverter to shut off the charger when it exceeds
the Absorb Voltage. This seems to work really well. When I was using a
generator it was necessary to run the built-in battery charger in the
OutBack inverter for at least an hour at the Absorb Voltage before they were
fully charged (according to my hydrometer). With my homebrew charger every
indication is that they are fully charged when the OutBack inverter decides
it's time to act. The voltages and activation times are adjustable so it's
easy to have the AUX active long enough for the engine to stop running and
still be able to restart it right away if necessary. This is the fastest,
and probably the most effecient way out of my three choices.
>
> And the amps should be restricted to the rating
> of the alternator. Some big GM cars came with 100 amp
> alternators, possibly as an option or certain models.
Currently (no pun intended) my amps are restricted by my small engine size.
>
> But a 12 volt alternator has 12 volt field coils,
> and most alternators on US cars have small brushes
> that have to carry the current to the rotating field,
> and higher voltage will burn out the field coils and
> damage the brush connections too.
>
>
>
>
>
| |
| Ulysses 2008-04-01, 1:25 pm |
|
"Neon John" <no@never.com> wrote in message
news:ed5uu3dnnn2d5h1ibcuh3c08v3no00sqes@4ax.com...
> On Sat, 29 Mar 2008 23:36:47 -0500, Whata Fool <whata@fool.ami> wrote:
>
resistor[color=darkred]
job[color=darkred]
connect[color=darkred]
>
> Actually, no it isn't. The only practical limitation is temperature and
in the case
> of automotive alternators, the insulation is high temperature rated, class
H or
> above. Like your handle. Apropos.
>
> Ulysses:
>
> The correct answer is, "I don't know". You'll have to monitor the
temperature of the
> field coil as you increase the current. If you're clever you can use the
field's
> resistance to measure the temperature. I'll describe how if you're
interested. The
> cooler the operating environment and the higher the air flow, the more
field current
> you can run.
I'm definately interested but my poor little brain is overloaded right now.
>
> I'm interested to hear what is in Don Young's adapter box. I've used
power from one
> of these gadgets before but I've never had one open. Meanwhile, through
the magic of
> Google, I found some info. I searched for "120 volts DC car alternator
kit
> -converter -inverter" without the quotes. The first useful hit is this
>
> http://islandcastaway.com/stuff/win...r%20Secrets.htm
Thanks for the link. I must be the world's worst Googler because I never
find the stuff that everyone else finds.
>
> Go down to "Modifications". He purports to knowing what is inside the
magic box.
> OTOH, I quickly spotted other mistakes on the page so.... That was all I
found on
> the first 100 results but there is probably more info deeper down.
>
> RE: diode voltage rating. What someone else said about the voltage rating
of the
> alternator's diodes was true in the past but isn't now and hasn't been for
several
> years. With the inclusion of more solid state controls and especially
> microprocessor-based controls, two problems had to be addressed. 1) EMI
caused by
> the abrupt recovery and turn-off of the alternator diodes on each
half-cycle and 2)
> load dumps. That is, high energy high voltage impulses caused by suddenly
> interrupting the current to an inductor. Typically the alternator field
and the
> starter motor.
>
> A voltage spike caused by a load dump didn't matter much
pre-microprocessor. About
> all one saw was a momentary brightening of various lamps. Nowadays it
does matter.
> The industry (for sure GM and Ford and probably everyone else) addressed
both of
> these problems with a new design diode. It's called a soft recovery
diode. When the
> voltage across the diode reverses on each half-cycle, it transitions
gradually from
> conducting to blocking, minimizing the EMI generated.
It sounds like something bad could happen if my
field-resistor-made-from-an-old-blowdryer suddenly failed.
>
> Another engineered feature of this diode is the low peak inverse voltage
rating. It
> is designed to conduct at a relatively low reverse voltage. An SAE
standard calls
> for no more than 60 volts to ever appear on the 12 volt supply so the
diode probably
> conducts (zeners) below that. This conduction clamps load dumps to no
more than the
> avalanche (zener) voltage.
>
> Bottom line: alternators with soft recovery rectifiers will not work for
high voltage
> generation. Which ones have these diodes? Got me. But it would be a
safe bet to
> regard any alternator 15 or less years old to have 'em until proved
otherwise. I
> know for a fact that the old large body Mopar alternators and the first
and second
> gen GM alternators do NOT have soft recovery diodes. The alternator on my
94 Caprice
> does. The safest plan would be to use external general purpose
rectifiers.
>
> Here are a couple of data points on alternator field excitation. The
first gen Mopar
> large frame alternator on my 68 Fury had 6-9 volts on the field for 14
volts out at
> idle. The GM/caddy alternator that I use on my CBC has 6-8 volts on the
field,
> depending on load, running at about 3,000 RPM.
>
> John
>
> --
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> http://www.johndearmond.com <-- best little blog on the net!
> Tellico Plains, Occupied TN
> Save a tree, kill a beaver
>
| |
| Ulysses 2008-04-01, 1:25 pm |
|
"Neon John" <no@never.com> wrote in message
news:cuq2v3hvt827f2flk78a38oivd1fv59spt@4ax.com...
> On Mon, 31 Mar 2008 07:33:36 -0800, "Ulysses" <eatmyspam@spamola.com/>
wrote:
>
>
obtain[color=darkred]
>
> Shhhhh! Don't let the secret out.
Oops!
>
> John
> --
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> http://www.johndearmond.com <-- best little blog on the net!
> Tellico Plains, Occupied TN
> Unable to locate Coffee -- Operator Halted!
>
| |
| Ulysses 2008-04-01, 1:25 pm |
|
"Johnny B Good" <jcs.computersbutt@plugzetnet.co.uk> wrote in message
news:313030303737303647F1907638@plugzetnet.co.uk...
> The message <uak1v39l3a5arquveh63iops6qcd3va3of@4ax.com>
> from Whata Fool <whata@fool.ami> contains these words:
>
>
>
>
>
> You're confusing ohm's law with the power law. Ignoring changes of
> resistance due to temperature, the current is directly in proportion to
> the voltage. It is power which is proportional to the square of the
> voltage (or current, take your pick).
>
>
>
>
> FYI, regarding metal halide lamps, the use of a halide and a high
> temperature envelope in close proximity to the filament is not to make
> the filament last longer at elevated temperature, it's to allow the lamp
> to maintain its lumen output over its shortened lifetime by recycling
> the tungsten vapour back onto the filament to save it from depositing on
> the envelope and acting as a light blocking filter.
>
> The tungsten halide cycle relies upon the envelope operating at much
> higher temperatures than possible with conventional glass to prevent the
> deposition of tungsten on the inner surface. The silicate glass used
> (the so called "Quartz Glass") usually operates at temperatures between
> 250 and 300 deg C. If you undervolt such a lamp, the cooler temperature
> on the envelope will compromise this effect and, although the filament
> life will be extended, the envelope will suffer blackening and reduce
> the lumen output.
>
> The reason why the tungsten halide cycle doesn't improve the filament
> life is because the tungsten vapour is deposited onto the cooler parts
> of the filament and its supports. The hotter parts of the filament still
> erode in pretty much the same way as in an ordinary vacuum or nitrogen
> filled lamp. This erosion thins the filament causing it to run even
> hotter in what is basically a runaway process.
>
> This wear mechanism is further agravated by the high current surge when
> such lamps are switched on from cold (cold filament resistance being
> only about one tenth of the operating temperature resistance). Since the
> ever so slightly to start with thinner parts of the filament heat up
> faster than the remaining thicker parts of the filament and to a
> slightly higher temperature than normal, the thinner parts suffer more
> loss of tungsten until they either fail at the next switch on (the usual
> fate for a household lamp) or else fail several hours after the fatal
> switch on event.
>
> Such "Thousand Hour" lamps can survive several thousands of hours, if
> left burning continuously and not subjected to switch on surges such
> lamps usually have to contend with in a normal domestic service
> environment.
>
> Regarding the maximum field current question, there is no point in
> allowing more current than the maximum based on the 12 volt excitation
> voltage since this will have been set, by design, for magnetic
> saturation or very close to. Additional current over and above this will
> produce very little extra magnetic flux but considerably more heat.
> Also, since this waste heat is a drain of power from the alternator's
> output, the overall efficiency will be significantly reduced.
OK, thanks. I think I understand that now. My confusion seems to stem from
something an auto mechanic once told me: there is a slot on the back
(non-pulley) side of some alternators and if you stick a screwdriver in
there it will "have full output." Well, after having taken apart my
alternator and studying what's inside the only thing I could see is that it
might test to see if the negative brush is bad. Did I miss something?
>
> I seem to recall a maximum excitation current figure of 4 amps for a
> 12v alternator. If such an alternator's voltage regulator were to be
> reconfigured to charge a "60 volt" lead acid battery and permitted to
> apply the full output voltage to the field, you could end up raising the
> excitation losses from about 50 watts to some 800 watts or more!
> Basically, there's no simple solution to this "problem" (there _are_
> solutions, but no simple ones).
I realize that my glowing red field resistor is wasting some power but my
bottom line is overall efficiency and so far it appears that I'm using about
25% less gasoline to charge by batteries compared to using a generator and
the OutBack built-in charger. If I can improve upon that I'm all ears.
>
> HTH & HAND
>
> --
> Regards, John.
>
> Please remove the "ohggcyht" before replying.
> The address has been munged to reject Spam-bots.
>
| |
| clare at snyder dot ontario dot canada 2008-04-01, 5:25 pm |
| On Tue, 1 Apr 2008 08:07:11 -0800, "Ulysses" <eatmyspam@spamola.com/>
wrote:
>
>"Johnny B Good" <jcs.computersbutt@plugzetnet.co.uk> wrote in message
>news:313030303737303647F1907638@plugzetnet.co.uk...
>
>OK, thanks. I think I understand that now. My confusion seems to stem from
>something an auto mechanic once told me: there is a slot on the back
>(non-pulley) side of some alternators and if you stick a screwdriver in
>there it will "have full output." Well, after having taken apart my
>alternator and studying what's inside the only thing I could see is that it
>might test to see if the negative brush is bad. Did I miss something?
It bypasses the regulator. The regulator does NOT supply voltage to
the feild - it supplies the GROUND to the field, thereby regulating
the voltage across, and the current through, the field coil.
--
Posted via a free Usenet account from http://www.teranews.com
| |
| Neon John 2008-04-01, 5:25 pm |
| On Tue, 1 Apr 2008 08:07:11 -0800, "Ulysses" <eatmyspam@spamola.com/> wrote:
>
>OK, thanks. I think I understand that now. My confusion seems to stem from
>something an auto mechanic once told me: there is a slot on the back
>(non-pulley) side of some alternators and if you stick a screwdriver in
>there it will "have full output." Well, after having taken apart my
>alternator and studying what's inside the only thing I could see is that it
>might test to see if the negative brush is bad. Did I miss something?
Like most of those shadetree "tricks", there is a kernel of truth but also the
ability to let lots of blue smoke out. There are two major architectures of field
regulation - high side and low side. High side regulation has the regulator between
the battery and field with the other side of the field grounded. The battery
attaches to the field on low side regulation and the regulator goes between the other
side of the field and ground.
IFF the alternator uses low side regulation AND the regulator brush is closest to the
housing then sticking that screwdriver in there and shorting the brush to ground will
turn the alternator full on.
OTOH, if the system is high side regulated, the screwdriver will either do nothing if
it hits the grounded brush or blow the regulator if it hits the other one.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Why the US is losing its competitivve edge:"It used to be that the USA was pretty good at
producing stuff teenaged boys could lose a finger or two playing with."-James Niccol
| |
| Neon John 2008-04-01, 5:25 pm |
| On Tue, 1 Apr 2008 07:53:05 -0800, "Ulysses" <eatmyspam@spamola.com/> wrote:
>temperature of the
>field's
>interested. The
>field current
>
>I'm definately interested but my poor little brain is overloaded right now.
While I'm thinking of it and have time to write, here's the Cliff Notes version.
Copper's resistance varies with temperature so it makes a good resistance temperature
device (RTD). In fact, copper RTDs used to be fairly popular (and may be again,
considering the price of platinum these days!)
The field coil's resistance changes with temperature. You can measure the change in
resistance and determine temperature. All you need is an oven and an ohmmeter
capable of reading 0.01 or better ohms, preferably with a Kelvin (4 terminal)
connection.
Measure the field resistance. Turn the pulley a few times to make sure the brushes
are making good contact. Put the alternator in an oven and increase the temperature
10 degree. Allow to soak. Measure the resistance. Increase another 10 degrees.
Measure the resistance. (you can do 20 degree steps with a little less precision). Go
up to at least 250 deg.
Plot those points on graph paper with resistance on the X axis and temperature on the
Y. Draw a curve through the points. It should be a smooth curve. Either toss any
outliers or re-measure at that point.
Start the alternator operating and apply field. Allow it to run long enough to
stabilize the temperature. Quickly remove the field excitation, connect your
ohmmeter and take a reading. Using your chart, convert the ohms to temperature.
Viola, the temperature of your operating field.
The easiest method to do this quickly is to hook the field to the battery and
ohmmeter through a DPDT center off toggle switch. Place a couple hundred ohm
resistor across the field terminals to absorb the inductive kick when opening the
field current. With the switch applying power to the field, let it operate as
needed. Flip to the center-off position and hesitate a couple of seconds before
flipping to ohmmeter to allow the inductive current to die down.
If you get any emf generated from stray fields in the alternator, stop it before each
measurement.
Easy as that.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
There are only 10 types of people in this world
Those who understand binary and those who don't.
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| daestrom 2008-04-01, 8:26 pm |
|
"Neon John" <no@never.com> wrote in message
news:bd35v3tuljs1oha19sh2etumddn5121nro@4ax.com...
> On Tue, 1 Apr 2008 07:53:05 -0800, "Ulysses" <eatmyspam@spamola.com/>
> wrote:
>
>
>
> While I'm thinking of it and have time to write, here's the Cliff Notes
> version.
> Copper's resistance varies with temperature so it makes a good resistance
> temperature
> device (RTD). In fact, copper RTDs used to be fairly popular (and may be
> again,
> considering the price of platinum these days!)
>
> The field coil's resistance changes with temperature. You can measure the
> change in
> resistance and determine temperature. All you need is an oven and an
> ohmmeter
> capable of reading 0.01 or better ohms, preferably with a Kelvin (4
> terminal)
> connection.
>
> Measure the field resistance. Turn the pulley a few times to make sure
> the brushes
> are making good contact. Put the alternator in an oven and increase the
> temperature
> 10 degree. Allow to soak. Measure the resistance. Increase another 10
> degrees.
> Measure the resistance. (you can do 20 degree steps with a little less
> precision). Go
> up to at least 250 deg.
>
> Plot those points on graph paper with resistance on the X axis and
> temperature on the
> Y. Draw a curve through the points. It should be a smooth curve. Either
> toss any
> outliers or re-measure at that point.
>
> Start the alternator operating and apply field. Allow it to run long
> enough to
> stabilize the temperature. Quickly remove the field excitation, connect
> your
> ohmmeter and take a reading. Using your chart, convert the ohms to
> temperature.
> Viola, the temperature of your operating field.
>
> The easiest method to do this quickly is to hook the field to the battery
> and
> ohmmeter through a DPDT center off toggle switch. Place a couple hundred
> ohm
> resistor across the field terminals to absorb the inductive kick when
> opening the
> field current. With the switch applying power to the field, let it
> operate as
> needed. Flip to the center-off position and hesitate a couple of seconds
> before
> flipping to ohmmeter to allow the inductive current to die down.
>
> If you get any emf generated from stray fields in the alternator, stop it
> before each
> measurement.
>
If you want a bit more precision, you can also factor in the brush /
slip-ring voltage drop. This voltage drop is pretty constant regardless of
current because its an electrolytic type of contact. There's a whole
science behind brush/ commutator or brush-slip-ring interface. Things like
humidity levels atmosphere contaminants, brush composition, and contact
pressure. But once measured, you'll find it doesn't vary much.
On large machines (multi-MW range), this same technique is used to measure
rotor temperature. The signal from a DC current shunt and the voltage
applied to the field are connected to a 'black box' that GE supplies with
the machine. It's basically a two-coil iron-vane meter movement with one
coil connected to each input and 'calibrated' with an internal rheostat in
the voltage circuit for the specific machine. The GE ones have an optical
sensor that monitors the needle movement (back side of the movement has a
vane with a slot that widens allowing more light through). When the
photocell gets enough light, it trips an alarm.
Circa 1960's technology, but still widely used today. Very robust.
daestrom
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| Whata Fool 2008-04-02, 3:25 am |
| "Ulysses" <eatmyspam@spamola.com/> wrote:
>"Whata Fool" <whata@fool.ami> wrote in message
>
>I measured 13.5 volts going to the field coil so it's looks like I'm right
>where I should be.
And you are using a precision voltage regulator. :-)
I am glad to hear somebody is using the ordinary
car alternator in alternate energy.
In my opinion, one 100 amp alternator is capable
of "powering" an Electric Vehicle in city driving (with
batteries and regenerative braking), and two of them
can probably power an EV at highway speeds on level ground.
| |
| Ulysses 2008-04-02, 1:25 pm |
|
"Whata Fool" <whata@fool.ami> wrote in message
news:n536v3l864rbfdh4ltarkjbprmtb0r4dbq@4ax.com...
> "Ulysses" <eatmyspam@spamola.com/> wrote:
>
right[color=darkred]
>
> And you are using a precision voltage regulator. :-)
Uh, yea. Sure. If it glows too brightly then it's not enough resistance.
> I am glad to hear somebody is using the ordinary
> car alternator in alternate energy.
A PMA would eliminate the wasted power due to controlling and supplying the
field current and I'm fiddleing around with that too. The one I have puts
out 155 VDC which is a bit too high for my purposes so rewinding the coils
seems to be the best solution with what I have on hand.
>
> In my opinion, one 100 amp alternator is capable
> of "powering" an Electric Vehicle in city driving (with
> batteries and regenerative braking), and two of them
> can probably power an EV at highway speeds on level ground.
How? If you are talking about using an engine to run the alternator to
power an electric motor wouldn't it be more efficient to just use a small
gasoline engine? One of the first Honda cars that was sold in the USA used
what amounted to a motorcycle engine and a chain drive. If I remember
correctly it was a two-seater and got over 40 mpg.
>
>
>
>
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| Whata Fool 2008-04-02, 8:25 pm |
| "Ulysses" <eatmyspam@spamola.com/> wrote:
>"Whata Fool" <whata@fool.ami> wrote in message
>
>How? If you are talking about using an engine to run the alternator to
>power an electric motor wouldn't it be more efficient to just use a small
>gasoline engine?
I don't think so, an Electric Vehicle allows a small
gasoline engine to run at optimum speed and efficiency
charging batteries (and/or supplying power to the electric
motor).
The electric motor needs to be big to get good
acceleration, and the batteries supply the power
for that. Wind drag and rolling resistance is
only about 15 horsepower at 50 MPH for all cars
having the same frontal area and streamlining.
Connecting a gasoline engine to the wheels
is a big mistake (at low speeds), the cause of
present poor gas mileage is the big gasoline
engine needed for acceleration uses more energy
to turn itself than the car requires to go 50.
I think the Prius may connect the gasoline
engine to the wheels after getting above a certain
speed, but it is a complex arrangement with a big
generator that also doubles as a motor for acceleration
plus an electric motor.
The reason for that complexity was the inadequate
state of battery technology and battery cost.
As the new technology batteries get into production,
the real Electric Vehicles will be possible, with about
100 miles per gallon possible eventually.
And Plug-in Electric Vehicles will be able to
do even better than that in reducing gasoline use,
giving effective gas mileage of 150 MPG.
And the people who have experience with any
type of generation and battery maintenance will be
needed to service the cars, only be careful, there
needs to be some good safety interlock cover panels
integrated with the battery connectors to prevent
accidents with 300+ volt systems.
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|
|
"Ulysses" <eatmyspam@spamola.com/> wrote in message
news:RINIj.35197$ZI6.6121@fe105.usenetserver.com...
>
> "Whata Fool" <whata@fool.ami> wrote in message
> news:n536v3l864rbfdh4ltarkjbprmtb0r4dbq@4ax.com...
> right
>
> Uh, yea. Sure. If it glows too brightly then it's not enough resistance.
>
>
> A PMA would eliminate the wasted power due to controlling and supplying the
> field current and I'm fiddleing around with that too. The one I have puts
> out 155 VDC which is a bit too high for my purposes so rewinding the coils
> seems to be the best solution with what I have on hand.
>
>
>
> How? If you are talking about using an engine to run the alternator to
> power an electric motor wouldn't it be more efficient to just use a small
> gasoline engine? One of the first Honda cars that was sold in the USA used
> what amounted to a motorcycle engine and a chain drive. If I remember
> correctly it was a two-seater and got over 40 mpg.
>
>
>
| |
|
|
"Ulysses" <eatmyspam@spamola.com/> wrote in message news:RINIj.35197
> How? If you are talking about using an engine to run the alternator to
> power an electric motor wouldn't it be more efficient to just use a small
> gasoline engine? One of the first Honda cars that was sold in the USA used
> what amounted to a motorcycle engine and a chain drive. If I remember
> correctly it was a two-seater and got over 40 mpg.
That would be the Honda 600. 600cc 2 cylinder air cooled engine. I believe it
did have a primary chain, oil immersed, thansfering power to the transaxle. The
'coupe' may have been a 2 seater, the 'sedan' was a "four seater" (the 2 in the
back had better be skinny) Tires were 145SR10's on the 2 I had. Unfortunately,
the crankshaft was pressed together around bearings that only lasted 50,000
miles, so every 50K you had to replace the crankshaft. The things drive like a
go-kart - really fun. I believe I got 30-35mpg.
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