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MHerder
Joined: 11 Feb 2008
Posts: 143
Location: Fort Worth TX
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 Posted: Sun Dec 26, 2010 1:18 pm Post subject: Voltage Regulator Output |
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I am using a Jabiru 3300 with a permanent magnet alternator and a kubota voltage regulator. I have some questions since I don't fully understand the PM alternator output.
1) What does the voltage out of the regulator look like on an oscilloscope? Is it really pure DC or does it have some squiggles that avionics may not do so well with?
2) Jabiru suggests tying the yellow wire (senses voltage and tells whether or not the system needs charge or dumps excess to ground) and the Red wire (charges battery) as close to the positive terminal as possible. I would like to charge and sense voltage at the starter contactor for the following reason... If I have an over voltage situation, I will get an alarm from my EIS and I can simply shut off my master switch which would hopefully prevent a problem.... Take a look at my schematic and let me know what you think.
3) What should the voltage be at say 800 RPM, 1500 RPM and 2800 RPM?
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MHerder
Joined: 11 Feb 2008
Posts: 124
Location: Fort Worth TX
Posted: Sun Dec 26, 2010 1:16 pm Post subject: Re: Voltage Regulator Output
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To clarify, my main concern is with damaging avionics since my charging would rin past the avionics bus on the way to the positive side of my battery. I also have concerns with what happens if the red and yellow are disconnected. Where would the voltage go, or would it just be an open circuit?
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flyadive(at)gmail.com
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| Posted: Sun Dec 26, 2010 2:52 pm Post subject: Voltage Regulator Output |
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Very interesting question M Herder... Is that Mike Herder?
I use to know a Mike Herder in high school.
| Quote: |
I am using a Jabiru 3300 with a permanent magnet alternator and a kubota voltage regulator. I have some questions since I don't fully understand the PM alternator output.
1) What does the voltage out of the regulator look like on an oscilloscope? Is it really pure DC or does it have some squiggles that avionics may not do so well with?
|
[Barry] - Lets back up a little to the ALTERNATOR. The out put there is pulsating DC. How much it pulsates is determined by the number and spacing of the magnets and coils on the armature.
This voltage is then sent to the Voltage Regulator (VR) a.k.a Alternator Control Unit (ACU)
http://www.bcae1.com/charging.htm
The ACU does have some very small amount of filtering to smooth out the pulsating DC / ripple, but not much.
Not much is really needed. Why? Because the BATTERY does the filtering.
You could parallel up one or some 50K uF capacitors but they will not do much. Unless you have AC noise in your system but, then you need to address more than just a capacitor at the battery. That is another question and answer.
| Quote: |
2) Jabiru suggests tying the yellow wire (senses voltage and tells whether or not the system needs charge or dumps excess to ground) and the Red wire (charges battery) as close to the positive terminal as possible. I would like to charge and sense voltage at the starter contactor for the following reason... If I have an over voltage situation, I will get an alarm from my EIS and I can simply shut off my master switch which would hopefully prevent a problem.... Take a look at my schematic and let me know what you think.
|
[Barry] - To clarify - It does NOT dump the voltage to ground. That would be a SHORT and you will be popping CB's all the time. Exactly how the voltage regulation is being done I would need a schematic of the VR. But, in most cases the Sense Voltage is used to turn ON and OFF either the FIELD - Which you do not have in a PM Alternator. Or a switching transistor to allow current flow.
" I will get an alarm from my EIS": <--- I think you meant that as a question. With the two EIS I have worked with YES you can set them up for a LOW and HIGH Limit alarm. What you do with this information is up to you and the design of your electrical system.
I would NOT want to be LIMITED to only turning on and off the Master Switch. That totally limits your ability to run off the battery. Can you post the schematic of your plane? Then I would be able to better answer what action should be taken.
If you installed a CB in series with the output of the alternator you would add protection and a means of shutting down the alternator output while allowing the Master to remain on.
Of course just like with any Split Master/Alternator you also have the addition requirement to REMEMBER to turn it ON.
| Quote: |
3) What should the voltage be at say 800 RPM, 1500 RPM and 2800 RPM?
|
[Barry] - Difficult question to answer.... TOO MANY VARIABLES. What you want to see for CHARGING is 13.8 to 14.2 VDC for a 12 volt system. Less than that and the battery will not charge. What you see is dependent on the speed of the alternator. What drives the alternator and what ratio of drive is there between the engine and the alternator. Some planes have an 11:1 drive increase. So even at idle say 650 RPM the alternator is spinning at 7150 RPM.
Measure the voltage right after start up and see what is happening.
For your other question: " also have concerns with what happens if the red and yellow are disconnected. Where would the voltage go, or would it just be an open circuit?" I would require a schematic of the VR.
Hope this helps?
Barry
[quote]
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MHerder
also have concerns with what happens if the red and yellow are disconnected. Where would the voltage go, or would it just be an open circuit?
[b]
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Clive J
Joined: 03 Nov 2007
Posts: 340
Location: UK
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| Posted: Sun Dec 26, 2010 4:20 pm Post subject: Voltage Regulator Output |
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Hi MH, I sent the schematic so Barry can update his comments.
The magnets are on the flywheel, it's a 12 pole alternator so the
squiggles are a factor of that and the engine revs.
Not really relevant to anything as we have what we have.
If you have chunky cables then being away from the battery positive a
little with the sense wire won't be an issue.
As Barry says the voltage will vary for several reasons but a typical
voltage reading on both my Jab engines is 14.4 volts at cruise (2750)
when the battery has recovered from the starting draw down. This is read
off my GPS as I don't have a big flat screen HD801 unfortunately.
The green wire can work a nice charging lamp, which if nothing else
lights up when the master is on and the engine isn't running, reminds
you to turn the master off when you get out the plane.
The interference from the generation system can cause a bit of a whine
to radios but good wiring practices and use of a filter (for the audio
stuff) will get rid of it. Most interference comes from the ignition
system.
Folk seem to fit most everything you could to Jab engined planes
nowadays and it all seems to work.
Having an option where you can run on your battery alone sounds like a
good one.
There's loads of discussion on this subject in the archives and you can
get loads of wiring diagrams if you ask. Lots of opinions also....
The Yahoo Jabiru engines group has the same stuff.
Regards, Clive
--
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craig(at)craigandjean.com
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| Posted: Sun Dec 26, 2010 5:37 pm Post subject: Voltage Regulator Output |
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There is a schematic of the regulator in the Jabiru manuals. And it contains a full-wave rectifier (with two legs formed with SCRs) because the alternator does put out AC. See the bottom of page 54 here:
http://www.usjabiru.com/images/pdf/manuals/new%20stuff/3300HL-IM.pdf
Quoting from the bottom of page 56 " The regulator performs rectification and voltage regulation. The regulator converts A.C. into D.C. which flows through the power consuming circuits and the battery, maintaining battery charge."
The regulator performs no filtering at all - it can't as all it can do is switch the SCR's on (they turn off when the voltage across the drops to zero as the voltage alternates). You can see some details here:
http://members.iinet.net.au/~cloutaa/Regulator.html
The battery does filter but it doesn't take out the high frequency components in the noise. That is why both Jabiru and Rotax (another engine with a PM alternator and a voltage rectifier/regulator) recommend large electrolytic capacitors in the circuit (25,000 microfarads or more).
-- Craig
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of FLYaDIVE
Sent: Sunday, December 26, 2010 2:49 PM
To: jabiruengine-list(at)matronics.com
Subject: Re: Voltage Regulator Output
Very interesting question M Herder... Is that Mike Herder?
I use to know a Mike Herder in high school.
| Quote: |
I am using a Jabiru 3300 with a permanent magnet alternator and a kubota voltage regulator. I have some questions since I don't fully understand the PM alternator output.
1) What does the voltage out of the regulator look like on an oscilloscope? Is it really pure DC or does it have some squiggles that avionics may not do so well with? |
[Barry] - Lets back up a little to the ALTERNATOR. The out put there is pulsating DC. How much it pulsates is determined by the number and spacing of the magnets and coils on the armature.
This voltage is then sent to the Voltage Regulator (VR) a.k.a Alternator Control Unit (ACU)
http://www.bcae1.com/charging.htm
The ACU does have some very small amount of filtering to smooth out the pulsating DC / ripple, but not much.
Not much is really needed. Why? Because the BATTERY does the filtering.
You could parallel up one or some 50K uF capacitors but they will not do much. Unless you have AC noise in your system but, then you need to address more than just a capacitor at the battery. That is another question and answer.
| Quote: |
2) Jabiru suggests tying the yellow wire (senses voltage and tells whether or not the system needs charge or dumps excess to ground) and the Red wire (charges battery) as close to the positive terminal as possible. I would like to charge and sense voltage at the starter contactor for the following reason... If I have an over voltage situation, I will get an alarm from my EIS and I can simply shut off my master switch which would hopefully prevent a problem.... Take a look at my schematic and let me know what you think. |
[Barry] - To clarify - It does NOT dump the voltage to ground. That would be a SHORT and you will be popping CB's all the time. Exactly how the voltage regulation is being done I would need a schematic of the VR. But, in most cases the Sense Voltage is used to turn ON and OFF either the FIELD - Which you do not have in a PM Alternator. Or a switching transistor to allow current flow.
" I will get an alarm from my EIS": <--- I think you meant that as a question. With the two EIS I have worked with YES you can set them up for a LOW and HIGH Limit alarm. What you do with this information is up to you and the design of your electrical system.
I would NOT want to be LIMITED to only turning on and off the Master Switch. That totally limits your ability to run off the battery. Can you post the schematic of your plane? Then I would be able to better answer what action should be taken.
If you installed a CB in series with the output of the alternator you would add protection and a means of shutting down the alternator output while allowing the Master to remain on.
Of course just like with any Split Master/Alternator you also have the addition requirement to REMEMBER to turn it ON.
| Quote: |
3) What should the voltage be at say 800 RPM, 1500 RPM and 2800 RPM? |
[Barry] - Difficult question to answer.... TOO MANY VARIABLES. What you want to see for CHARGING is 13.8 to 14.2 VDC for a 12 volt system. Less than that and the battery will not charge. What you see is dependent on the speed of the alternator. What drives the alternator and what ratio of drive is there between the engine and the alternator. Some planes have an 11:1 drive increase. So even at idle say 650 RPM the alternator is spinning at 7150 RPM.
Measure the voltage right after start up and see what is happening.
For your other question: " also have concerns with what happens if the red and yellow are disconnected. Where would the voltage go, or would it just be an open circuit?" I would require a schematic of the VR.
Hope this helps?
Barry
| Quote: |
-------------------------------------------------------------------------
Regulator Wiring.pdf
Description:
Download
Filename: Regulator Wiring.pdf
Filesize: 10.58 KB
Downloaded: 1 Time(s)
--------------------------------------------------------------------------------
_________________
One Rivet at a Time!
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MHerder
also have concerns with what happens if the red and yellow are disconnected. Where would the voltage go, or would it just be an open circuit? |
0123456789012345678
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flyadive(at)gmail.com
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| Posted: Mon Dec 27, 2010 12:04 pm Post subject: Voltage Regulator Output |
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Mike:
I led you in a skewed direction.
Clive was kind and sending me directly the manual for the Jabiru engine.
And in reading it there are confusions due to the misuses of words.
Jabiru bounces back and forth between Generator and Alternator.
On one page in one statement they use the term Generator <-- Which is CORRECT.
Then they jump to the term Alternator which obviously is not correct.
The ring of coils and the moving magnets is a Generator.
Why? Because the output is AC and it is NOT being rectified (converted) to DC within the same housing.
OK, let me further confuse you... Generators put out AC. Yet Alternators MAKE AC and then rectify it to DC all within the same housing. Yes, there are DC generators but they are inefficient, too big and too heavy to be used in planes. It is much easier to produce AC and then convert it to DC.
So, let me re-answer your questions:
[Mike] - "1) What does the voltage out of the regulator look like on an oscilloscope? Is it really pure DC or does it have some squiggles that avionics may not do so well with?"
[Barry] - The output taken directly from the two wires at the coil is AC. See page 55, the wires at NOTE 5.
It is a sine wave and goes positive and negative. The output from there goes to the input of the RECTIFIER / REGULATOR. Jubiru calls it a Regulator but that does not fully explain it function. Yet on page 56 they do further breakdown the device with a good explanation. See page 7.4.1.7 Notice the wires going to and from the battery to pins 2 & 6. Pin 2 is NEGATIVE and Pin 6 is POSITIVE.
And at that point you were to put a 'O' Scope you will see a PULSATING DC - The output there is pulsating DC. How much it pulsates is determined by the number and spacing of the magnets and coils on the armature. The schematic on page 54 (7.4.1.6) is a bit crude in that is is missing a few components for proper operation. They were more than likely left off for ease of explanation. I'm sure there are a few capacitors within the housing. They would be there to remove and prevent transients to the transistors and offer a little filtering.
| Quote: | [Mike] - 2) Jabiru suggests tying the yellow wire (senses voltage and tells whether or not the system needs charge or dumps excess to ground) and the Red wire (charges battery) as close to the positive terminal as possible. I would like to charge and sense voltage at the starter contactor for the following reason... If I have an over voltage situation, I will get an alarm from my EIS and I can simply shut off my master switch which would hopefully prevent a problem.... Take a look at my schematic and let me know what you think.
|
[Barry] - To clarify - It does NOT dump the voltage to ground. That would be a SHORT and you will be popping CB's all the time. Exactly how the voltage regulation is being done I would need a schematic of the VR. But, in most cases the Sense Voltage is used to turn ON and OFF either the FIELD - Which you do not have in a PM Alternator. Or a switching transistor to allow current flow.
" I will get an alarm from my EIS": <--- I think you meant that as a question. With the two EIS I have worked with YES you can set them up for a LOW and HIGH Limit alarm. What you do with this information is up to you and the design of your electrical system.
I would NOT want to be LIMITED to only turning on and off the Master Switch. That totally limits your ability to run off the battery. Can you post the schematic of your plane? Then I would be able to better answer what action should be taken.
If you installed a CB in series with the output of the alternator you would add protection and a means of shutting down the alternator output while allowing the Master to remain on.
Of course just like with any Split Master/Alternator you also have the addition requirement to REMEMBER to turn it ON.
EXPLANATION CONTINUED -
Mike, looking at the schematic they are turning ON and OFF the switching transistors. There would be some ripple and as i mentioned before a 50K uF Capacitor will greatly help the filtering.
| Quote: | [Mike] - 3) What should the voltage be at say 800 RPM, 1500 RPM and 2800 RPM?
|
[Barry] - Difficult question to answer.... TOO MANY VARIABLES. What you want to see for CHARGING is 13.8 to 14.2 VDC for a 12 volt system. Less than that and the battery will not charge. What you see is dependent on the speed of the alternator. What drives the alternator and what ratio of drive is there between the engine and the alternator. Some planes have an 11:1 drive increase. So even at idle say 650 RPM the alternator is spinning at 7150 RPM.
Measure the voltage right after start up and see what is happening.
For your other question: " also have concerns with what happens if the red and yellow are disconnected. Where would the voltage go, or would it just be an open circuit?" I would require a schematic of the VR.
Mike - I do have the schematic but it does not indicate what the red & yellow wires are. Taking a guess the RED wire should be B+ which goes to the Battery Positive terminal. The YELLOW is SENSE and goes to the BUSS.
So, if RED is disconnected the output goes to ZERO in the way the battery will not charge.
And if the YELLOW is disconnected ... I'm not sure... It should put a low voltage on emitter side of the transistor as compared to the base being held at some Zener voltage ... But, I'm still not 100% sure. Let me think about it.
Hope this helps?
Barry
[quote] --------------------------------------------------------------------------------
To clarify, my main concern is with damaging avionics since my charging would rin past the avionics bus on the way to the positive side of my battery. I also have concerns with what happens if the red and yellow are disconnected. Where would the voltage go, or would it just be an open circuit?
--------
One Rivet at a Time!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=324583#324583
[b]
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dave.go
Joined: 20 Jul 2009
Posts: 26
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| Posted: Mon Dec 27, 2010 1:05 pm Post subject: Voltage Regulator Output |
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I am not in any way a stickler for terminology and correctness, I figure if most people understand what you are trying to communicate, job done.
But I was taught, way back in the dark ages of coal and steam that anything that converted mechanical energy into electricity was in fact a generator (of electricity). There were dynamos which used commutators to issue forth DC electricity, called generators in the US and AC generators called alternators in auto applications, which were externally rectified. The advent of the internal rectifier came later. I think in the case of practical usage any AC generator could be called either generator or alternator without causing undue hardship to the reader. Both dynamos and ac generators are noisy, as are many voltage regulators, part of my job in years past was to measure and mitigate this noise.
My advice to the original poster of the question is this. The ripple or noise is not likely to harm your avionics, but may in some cases reduce it’s sensitivity to signal. If you are getting satisfactory performance, and not hearing any objectionable noise I would not worry much about it. If you are hearing noise or you feel it is reducing your reception add a filter for the radio comprised of an induction (filter) coil and a capacitor. I would do this only for the radios, I doubt if anything else would care. Put the cap on the output of the regulator and the filter coid on the power feed to the radio.
If others feel differently, fine with me.
From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of FLYaDIVE
Sent: December-27-10 3:02 PM
To: jabiruengine-list(at)matronics.com
Subject: Re: JabiruEngine-List: Voltage Regulator Output
Mike:
I led you in a skewed direction.
Clive was kind and sending me directly the manual for the Jabiru engine.
And in reading it there are confusions due to the misuses of words.
Jabiru bounces back and forth between Generator and Alternator.
[quote][b]
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dave.go
Joined: 20 Jul 2009
Posts: 26
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| Posted: Mon Dec 27, 2010 2:20 pm Post subject: Voltage Regulator Output |
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In further reading the thread I noticed some information about voltage regulators, and DC generators that appeared to be incorrect.
First DC generators in the form of what I would call a dynamo and Americans would call a generator are not uncommon on certified aircraft of a certain age. They can be seen in the ACS catalogue or inside the cowling of a Cessna 150.
Voltage regulator/rectifiers as fitted to the permanent magnet AC generators of Rotax and Jabiru engines are often of the shunt type and do in fact dump excess voltage directly to ground, the alternative is a series type regulator which places it’s regulating device in series with the load. The advantages of each are available on the internet and most of what I have seen appears correct. The one supplied with the Jabiru looks like a shunt regulator. They are generally very reliable.
[quote][b]
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