Overspeed alarm based on alternator frequency
 

My engine panel overspeed alarm is driven by the freq output from the
alternator from the AC taps. The overspeed alarm goes off when the
alternator speed is 5000rpm, equiv to engine speed 2300rpm. With a new
alternator, I've reduced the pulley size considerably and the alt speed
is 5000 rpm at 1400 engine rpm - and the alarm now goes off.
The engine panel has a pot to adjust the overspped freq but looking at
the service bulletin the freq will be outside its adjsutment range
I've got 2 options - the easy one - disconnect the wire - is an
overspeed really necessary or useful??
Try and get a device to divide the frequency.

Grateful for any ideas.

Overspeed alarm based on alternator frequency
 

CS inscribed in red ink for all to know:
My engine panel overspeed alarm is driven by the freq output from the
alternator from the AC taps. The overspeed alarm goes off when the
alternator speed is 5000rpm, equiv to engine speed 2300rpm. With a new
alternator, I've reduced the pulley size considerably and the alt speed
is 5000 rpm at 1400 engine rpm - and the alarm now goes off.
The engine panel has a pot to adjust the overspped freq but looking at
the service bulletin the freq will be outside its adjsutment range
I've got 2 options - the easy one - disconnect the wire - is an
overspeed really necessary or useful??
Try and get a device to divide the frequency.

Grateful for any ideas.


change the alternator pulley back to the one from the old alternator?

bob

Overspeed alarm based on alternator frequency
 

Colin,

It would be neat if you gave us any idea what this is about:
What engine,
What alernator
anything else that might interesting.

Are you so far from the engine that you could not hear it?

Matt Colie

CS wrote:
My engine panel overspeed alarm is driven by the freq output from the
alternator from the AC taps. The overspeed alarm goes off when the
alternator speed is 5000rpm, equiv to engine speed 2300rpm. With a new
alternator, I've reduced the pulley size considerably and the alt speed
is 5000 rpm at 1400 engine rpm - and the alarm now goes off.
The engine panel has a pot to adjust the overspped freq but looking at
the service bulletin the freq will be outside its adjsutment range
I've got 2 options - the easy one - disconnect the wire - is an
overspeed really necessary or useful??
Try and get a device to divide the frequency.

Grateful for any ideas.

Overspeed alarm based on alternator frequency
 

Engine is a Daewoo L136 and the original alternator, 50A 5000 rpm max
continuous, was replaced by a Leece Neville unit, 110A 8000 rpm max
cont . To get more amps from the alternator, I reduced the pulley so
8000 alt rpm is now achieved at just over 2300 engine rpm - engien
normal max is 2200 rpm. The engine is beneath my feet in a luxemotor
barge - so I think the oversped is somewhat superfluous.

Overspeed alarm based on alternator frequency
 

"CS" wrote in news:1160512470.107776.32410
@c28g2000cwb.googlegroups.com:

I've got 2 options - the easy one - disconnect the wire - is an
overspeed really necessary or useful??
Try and get a device to divide the frequency.



As alternator speed has NOTHING to do with its output once it's just off
idle, why not put the right pulley back on it, correcting the problem and
saving the alternator bearings from overspeed, themselves...premature
failure.

Spinning an alternator so fast DOESN'T make it put out another amp....

No, you can't charge the house batteries in 5 minutes, either....(sigh)


--
There's amazing intelligence in the Universe.
You can tell because none of them ever called Earth.

Overspeed alarm based on alternator frequency
 

As alternator speed has NOTHING to do with its output once it's just off
idle, why not put the right pulley back on it, correcting the problem and
saving the alternator bearings from overspeed, themselves...premature
failure.
Spinning an alternator so fast DOESN'T make it put out another amp....

COMPLETELY INCORRECT - look at the output curve for the alternator here
-
http://www.prestolite.com/images_alt...161U_curve.pdf

At engine idle, alt will be at 2500 and deliver 85A. With old pulley
off original alt, alt is only at 1500rpm and output is only 35A - so
quite a useful increase.

Output therefore CLEARLY varies considerably with speed and the spec
sheet I got from Prestolite has it continuously rated for 8000 rpm - so
it is not being overspeeded.

Fundamental AC - the higher the freq (= more rpm) the greater the power
that can be transmitted. Which is why aircraft AC systems are often at
400Hz - smaller kit but higher power.

No, you can't charge the house batteries in 5 minutes, either....(sigh)

At 110A a 920Ah battery is going to charge a hell of a lot quicker than
at 50A. I'll leave you to do the sums.

Overspeed alarm based on alternator frequency
 

Higher AC frequencies are good for transformers, but don't have an effect on the
transmission of power reasonable distances and a boat is way smaller than that.
But since your AC is being converted to DC, the transformer argument is
irrelevant.

And your AC frequency will be pretty high start with -- there's more than one
cycle per rev.

"CS" wrote in message ups.com...
As alternator speed has NOTHING to do with its output once it's just off
idle, why not put the right pulley back on it, correcting the problem and
saving the alternator bearings from overspeed, themselves...premature
failure.
Spinning an alternator so fast DOESN'T make it put out another amp....

COMPLETELY INCORRECT - look at the output curve for the alternator here
-
http://www.prestolite.com/images_alt...161U_curve.pdf

At engine idle, alt will be at 2500 and deliver 85A. With old pulley
off original alt, alt is only at 1500rpm and output is only 35A - so
quite a useful increase.

Output therefore CLEARLY varies considerably with speed and the spec
sheet I got from Prestolite has it continuously rated for 8000 rpm - so
it is not being overspeeded.

Fundamental AC - the higher the freq (= more rpm) the greater the power
that can be transmitted. Which is why aircraft AC systems are often at
400Hz - smaller kit but higher power.

No, you can't charge the house batteries in 5 minutes, either....(sigh)

At 110A a 920Ah battery is going to charge a hell of a lot quicker than
at 50A. I'll leave you to do the sums.

Overspeed alarm based on alternator frequency
 

"CS" wrote in news:1160536091.872456.50110
@m73g2000cwd.googlegroups.com:

At 110A a 920Ah battery is going to charge a hell of a lot quicker than
at 50A. I'll leave you to do the sums.




Hmm.....is the regulator shorted?....

Over and over boaters report on here how quickly their huge battery banks
drop off full current to 20A or 30A, tapering quickly to their
consternation as the regulators do their jobs, much to their dismay....

LEAD ACID BATTERIES CHARGE VERY SLOWLY....hours and hours.

You CANNOT charge a 920AH battery from 50% to full charge in the 5
minutes they all want to run the engine charging
batteries................yet.

However, the solution IS on the radar:
http://www.toshiba.co.jp/about/press/2005_03/pr2901.htm
80% in 60 seconds....
100% in 3 minutes flat....
99% charge recovery after 1000 deep, deep cycles!

Hmmm...the sums....950 AH new Li-Ion nanobeast charge in 60 seconds to
80% = 760AH....that would be 760A if we charged it in an hour but we're
gonna charge it 60 times faster than that so 760A x 60 = 45,600A X 14.2V
= 647,520 watts for 60 seconds divided by 746w/HP = 867HP for a
minute....Hmm....don't think the Yanmar 3GM is gonna like that....How
many v-belts does it take to drive a 45,600A alternator, anyways?? Can
we mount the 700KW alternator where the aft cabin used to be?

Maybe it'll charge it on your 110A charger running wide open for 950
divided by 110 = 8.6 hours....does that sound better? The new battery
won't even get warm at 110 amps...It's internal resistance must be in
nano-ohms to take a huge charging current like they do.

Thankfully, the 1920's technology lead-acid wetcell's days are
numbered.... Still no news I've found when the Nano-Li-Ions will be
marketed. I suspect the auto and oil industries are heavily pressuring
Toshiba and the other developers to flush the damned inventor and his
notes down the toilet like they did all the EV cars (EV-1/GM remember
them? All EV-1s were confiscated and crushed after dealers bitched they
wouldn't need constant, expensive maintenance and repairs, the dealer's
gravy train.) With THIS battery, the EV-1 would refuel in less time than
it took to refill the Ford Exploder at god-awful amps/volts and every
time you pressed the "brake" pedal, the huge power generated would
restore the charge on the new Li-Ion cells under the trunk, instantly,
not wasted trying to charge slowcharge batteries like now. Man, what an
electric car we'd have if the *******s in control don't bury it, again!

A side note: I've seen the webpage of the Dell notebook with the
defective Li-Ion battery exploding on some conference table in a hotel.
Very violent and very hot! It was about 4AH...Wonder what the fire will
look like on a 950A Li-Ion house battery?? Will there be any boat left?
There wasn't much notebook left...or table it was sitting on!

--
There's amazing intelligence in the Universe.
You can tell because none of them ever called Earth.

Overspeed alarm based on alternator frequency
 

Higher AC frequencies are good for transformers, but don't have an effect on the
transmission of power reasonable distances and a boat is way smaller than that.
But since your AC is being converted to DC, the transformer argument is
irrelevant.

I'm lost - I have not mentioned transformers???

And your AC frequency will be pretty high start with -- there's more than one
cycle per rev.

Yes, a 10 pole alt at 8000 rpm is generating AC at around 1332Hz. More
A can be produced at 1332Hz than at 50Hz.

Overspeed alarm based on alternator frequency
 

"Larry" wrote

As alternator speed has NOTHING to do with its output once it's just off
idle, why not put the right pulley back on it, correcting the problem and
saving the alternator bearings from overspeed, themselves...premature
failure.

Spinning an alternator so fast DOESN'T make it put out another amp....

Look at any alternator output curve and you will see that amps increase as
RPM increases up to the point where they approach full output and then level
out. That point is usually between 2500 and 3500 shaft RPM. There are a
very few very expensive alternators, like the Eco-Tech, that are built to
produce close to full output at less than 2000 RPM that have a very steep
curve but most alternators require a minimum 2500 RPM to reach any
significant output.

That said, the OP's choice of alternators may not be the best if he wants to
charge at dead idle. The output curve has a particularly slow slope. He
should also consider that it takes a certain amount of power to produce 85
amps. Besides the output, the other item on that chart he should consider
is the Torque curve. When you use a pulley ratio that allows close to full
output at 800 engine RPM the torque increases to the point that invites belt
failure and excessive side loads on bearings.

His best option is to reduce the ratio closer to the original and charge at
1200 to 1500 engine RPM.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Overspeed alarm based on alternator frequency
 

Look at any alternator output curve and you will see that amps increase as
RPM increases up to the point where they approach full output and then level
out. That point is usually between 2500 and 3500 shaft RPM. There are a
very few very expensive alternators, like the Eco-Tech, that are built to
produce close to full output at less than 2000 RPM that have a very steep
curve but most alternators require a minimum 2500 RPM to reach any
significant output.

Look at the LN curve I've posted - it is not as stated above. Full
output is at 5000 alt rpm and it then levels out.

That said, the OP's choice of alternators may not be the best if he wants to
charge at dead idle. The output curve has a particularly slow slope. He
should also consider that it takes a certain amount of power to produce 85
amps. Besides the output, the other item on that chart he should consider
is the Torque curve. When you use a pulley ratio that allows close to full
output at 800 engine RPM the torque increases to the point that invites belt
failure and excessive side loads on bearings.

My engine can deliver up to 20kW at engine idle according to the makers
engine manual - more than enough for the 2 - 3 kW taken by the
alternator. Torque will also not be an issue with dual belts.

Overspeed alarm based on alternator frequency
 

Look at the LN curve I've posted - it is not as stated above. Full
output is at 5000 alt rpm and it then levels out.

That is what I meant about "OP's choice of alternators may not be the best
". That particular alternator has a relatively slow slope up to full power.

My engine can deliver up to 20kW at engine idle according to the makers
engine manual - more than enough for the 2 - 3 kW taken by the
alternator. Torque will also not be an issue with dual belts.

Off which end? My Yanmar can handle a lot of torque off the back end but
the front crankshaft bearings are not designed to handle a lot of side load.
Double belts will stop the slippage but a double pulley extends the center
of load further from the bearing increasing the leverage of the side load.

There is also the principle that diesel engines are much happier running at
1800 RPM than they are at 800. For many reasons running at idle under light
loads for long periods is hard on diesels. I am not saying don't do it.
Just that there are better ways to tackle the problem.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Overspeed alarm based on alternator frequency
 

Fundamental AC - the higher the freq (= more rpm) the greater the power
that can be transmitted. Which is why aircraft AC systems are often at
400Hz - smaller kit but higher power.

I was explaining why aircraft sometimes use 400Hz AC -- because they can carry
smaller transformers.

I won't disagree that you can generate (not transmit) more power by spinning the
alternator faster (up to a limit).

"CS" wrote in message ups.com...


Higher AC frequencies are good for transformers, but don't have an effect on the
transmission of power reasonable distances and a boat is way smaller than that.
But since your AC is being converted to DC, the transformer argument is
irrelevant.

I'm lost - I have not mentioned transformers???

And your AC frequency will be pretty high start with -- there's more than one
cycle per rev.

Yes, a 10 pole alt at 8000 rpm is generating AC at around 1332Hz. More
A can be produced at 1332Hz than at 50Hz.

Overspeed alarm based on alternator frequency
 

Glenn Ashmore wrote:

Look at the LN curve I've posted - it is not as stated above. Full
output is at 5000 alt rpm and it then levels out.

That is what I meant about "OP's choice of alternators may not be the best
". That particular alternator has a relatively slow slope up to full power.

My engine can deliver up to 20kW at engine idle according to the makers
engine manual - more than enough for the 2 - 3 kW taken by the
alternator. Torque will also not be an issue with dual belts.

Off which end? My Yanmar can handle a lot of torque off the back end but
the front crankshaft bearings are not designed to handle a lot of side load.
Double belts will stop the slippage but a double pulley extends the center
of load further from the bearing increasing the leverage of the side load.

Off the front crankshaft and or a PTO shaft. The engine is an 8 litre
6 cyl natural aspirated 160 Hp engine which weights 1000kg and is a
proper industrial marine engine as used by fishing vessels - not a
bleeding micky mouse Yanmar engine designed for pleasure yachts. I
have done a certain amount of research and I am amazed by the complete
rubbish being spouted about alternators.

Overspeed alarm based on alternator frequency
 

Colin,

Don't sweat the overspeed.

Unfortunately, this engine is too new for my catalogues, but I and quite
sure that it is using a Hitachi copy of a Bosch TE injection pump. This
pump includes a controlling governor that not only controls the engine
to produce the ordered crankshaft speed but also limits the speed to a
safe maximum. The only way to exceed that speed is by introducing
additional fuel (often that is injested lube oil) and it that occurs
there is often little the operator can do without getting too close to
the engine.

I was glad to see that you are running double belts because that is just
about and maybe a little bit over the capability of a single belt.

Matt Colie
Lifelong Waterman, Licensed Mariner (Diesel Chief...)



CS wrote:
Engine is a Daewoo L136 and the original alternator, 50A 5000 rpm max
continuous, was replaced by a Leece Neville unit, 110A 8000 rpm max
cont . To get more amps from the alternator, I reduced the pulley so
8000 alt rpm is now achieved at just over 2300 engine rpm - engien
normal max is 2200 rpm. The engine is beneath my feet in a luxemotor
barge - so I think the oversped is somewhat superfluous.

Overspeed alarm based on alternator frequency
 

Colin,
I'm really confused. If you already know so much about alternators, why ask
your question to the group in the first place? Glenn has expressed very
valid concerns when equiping an engine with an alternator. It appears that
you have out engineered yourself. If you need to spin your alternator 8k rpm
to get it to perform, you have clearly chosen the wrong alternator. Go out
and buy a proper large magnet Leese-Neville industrial grade alternator and
spin the thing acording to OEM instructions. Problem solved.
Steve

"CS" wrote in message
ups.com...

Glenn Ashmore wrote:

Look at the LN curve I've posted - it is not as stated above. Full
output is at 5000 alt rpm and it then levels out.

That is what I meant about "OP's choice of alternators may not be the
best
". That particular alternator has a relatively slow slope up to full
power.

My engine can deliver up to 20kW at engine idle according to the makers
engine manual - more than enough for the 2 - 3 kW taken by the
alternator. Torque will also not be an issue with dual belts.

Off which end? My Yanmar can handle a lot of torque off the back end but
the front crankshaft bearings are not designed to handle a lot of side
load.
Double belts will stop the slippage but a double pulley extends the
center
of load further from the bearing increasing the leverage of the side
load.

Off the front crankshaft and or a PTO shaft. The engine is an 8 litre
6 cyl natural aspirated 160 Hp engine which weights 1000kg and is a
proper industrial marine engine as used by fishing vessels - not a
bleeding micky mouse Yanmar engine designed for pleasure yachts. I
have done a certain amount of research and I am amazed by the complete
rubbish being spouted about alternators.

Overspeed alarm based on alternator frequency
 

On Sat, 14 Oct 2006 05:52:24 +0200, "Steve Lusardi"
wrote:

Colin,
I'm really confused. If you already know so much about alternators, why ask
your question to the group in the first place? Glenn has expressed very
valid concerns when equiping an engine with an alternator. It appears that
you have out engineered yourself. If you need to spin your alternator 8k rpm
to get it to perform, you have clearly chosen the wrong alternator. Go out
and buy a proper large magnet Leese-Neville industrial grade alternator and
spin the thing acording to OEM instructions. Problem solved.
Steve
Colin did not originally ask about specifying an alternator,he was
discussing engine overspeed alarm requirements.
The alternator he indicated is a Leece-Neville!

I cannot see the problem with his setup!

Richard

Nb "Pound Eater" Parkend G+S

Overspeed alarm based on alternator frequency
 

Richard,
Colin's overspeed problem started when he changed the speed of the
alternator. He needs to use an alternator that generates the required power
at the original alternator speed. He may have a Leece-Neville alternator,
but it is not the large magnet variety, if he has to spin it at 8K rpm.
Steve

"Electricky Dicky" wrote in message
...
On Sat, 14 Oct 2006 05:52:24 +0200, "Steve Lusardi"
wrote:

Colin,
I'm really confused. If you already know so much about alternators, why
ask
your question to the group in the first place? Glenn has expressed very
valid concerns when equiping an engine with an alternator. It appears that
you have out engineered yourself. If you need to spin your alternator 8k
rpm
to get it to perform, you have clearly chosen the wrong alternator. Go out
and buy a proper large magnet Leese-Neville industrial grade alternator
and
spin the thing acording to OEM instructions. Problem solved.
Steve
Colin did not originally ask about specifying an alternator,he was
discussing engine overspeed alarm requirements.
The alternator he indicated is a Leece-Neville!

I cannot see the problem with his setup!

Richard

Nb "Pound Eater" Parkend G+S

Overspeed alarm based on alternator frequency
 

Steve Lusardi wrote:
Richard,
Colin's overspeed problem started when he changed the speed of the
alternator. He needs to use an alternator that generates the required power
at the original alternator speed. He may have a Leece-Neville alternator,
but it is not the large magnet variety, if he has to spin it at 8K rpm.
Steve

OK - I've just looked at the military alternators and indeed some do
generate full power at a lowly 2500/3000 rpm. But they are pretty vast
bits of kit and will not readily mount on my engine. The work involved
to fit would immense. A small pulley for £10 and disconnect a wire is
a simple cost effective option. BTW my 240v AC alternator on the same
engine spins up to 14000 rpm quite happily.

Overspeed alarm based on alternator frequency
 

CS,
They are not just Military, they are industrial as well. They can be found
on all big trucks, gererators, water pumps and other stationary diesel
applications. I assume you are in England. If so go to www.valkenpower.com
Call or send an email to Jack. They are in Holland and the prices are good.
Tell him Steve sent you.
Steve


"CS" wrote in message
ups.com...

Steve Lusardi wrote:
Richard,
Colin's overspeed problem started when he changed the speed of the
alternator. He needs to use an alternator that generates the required
power
at the original alternator speed. He may have a Leece-Neville alternator,
but it is not the large magnet variety, if he has to spin it at 8K rpm.
Steve

OK - I've just looked at the military alternators and indeed some do
generate full power at a lowly 2500/3000 rpm. But they are pretty vast
bits of kit and will not readily mount on my engine. The work involved
to fit would immense. A small pulley for £10 and disconnect a wire is
a simple cost effective option. BTW my 240v AC alternator on the same
engine spins up to 14000 rpm quite happily.