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Regulator trouble?

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bicyclop(at)pacbell.net
Guest

Posted: Wed Jun 13, 2007 8:35 pm Post subject: Regulator trouble?

Howdy,



The other day, the low volt light started flashing and I found the field 

breaker popped. This is an LR3C with the notorious Van's 35 amp 

alternator. I reset the breaker and about 5 minutes later, it popped 

again. The voltage had been running about 14.6 which seemed a little 

much so I reset it and turned on some lights. The voltage ran about 13.9 

to 14 and the breaker didn't pop for quite a while. About the time I 

thought that it was cool, the low volt light came on again, but this 

time the breaker wasn't out. I turned off the master and flew another 

hour and a half, including a stop for gas, and landed at Aurora. I found 

a bit of hangar space and pulled the alternator. It had a lot of end 

play and tested bad at the local auto parts place. I bought another one 

at Van's - they tried to talk me out of it, but I didn't want to rewire 

the airplane for the internally regulated unit a long way from home. 

Hey, I would have happily spent the extra for the B&C alternator, but I 

was in Aurora not Wichita.



It charges just fine, in fact it'll hold voltage at idle with lights on 

which is more than the old one would do. It is also running at about 

14.5 or .6 and the breaker has popped 3 times so far. The breaker resets 

and the alternator runs fine for a while, but I'm wondering if I'll blow 

up the new alternator, too. Do you think that the regulator is a bit 

wonky? Is the voltage too high? Am I frying my battery? Is the 

overvoltage module overactive?



Pax,



Ed Holyoke

nuckollsr(at)cox.net
Guest

Posted: Thu Jun 14, 2007 6:09 am Post subject: Regulator trouble?

At 09:31 PM 6/13/2007 -0800, you wrote:



 	  Quote: 	
		  



Howdy,



The other day, the low volt light started flashing and I found the field 

breaker popped. This is an LR3C with the notorious Van's 35 amp 

alternator. I reset the breaker and about 5 minutes later, it popped 

again. The voltage had been running about 14.6 which seemed a little much 

so I reset it and turned on some lights. The voltage ran about 13.9 to 14 

and the breaker didn't pop for quite a while. About the time I thought 

that it was cool, the low volt light came on again, but this time the 

breaker wasn't out. I turned off the master and flew another hour and a 

half, including a stop for gas, and landed at Aurora. I found a bit of 

hangar space and pulled the alternator. It had a lot of end play and 

tested bad at the local auto parts place. I bought another one at Van's - 

they tried to talk me out of it, but I didn't want to rewire the airplane 

for the internally regulated unit a long way from home. Hey, I would have 

happily spent the extra for the B&C alternator, but I was in Aurora not 

Wichita.



It charges just fine, in fact it'll hold voltage at idle with lights on 

which is more than the old one would do. It is also running at about 14.5 

or .6 and the breaker has popped 3 times so far.


	


    You need to conduct and investigation of system performance

    as outlined in note 8 of



http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf



    and take some readings. In fact, get an el-cheapo analog

    voltmeter for observing field voltage. It's more important

    to know how stable it is than to know the exact voltage reading.



 	  Quote: 	
		    The breaker resets and the alternator runs fine for a while, but I'm 

 wondering if I'll blow up the new alternator, too.


	


    No, I cannot think of any abuse (other than lack of cooling)

    that you could heap on an externally regulated alternator

    from outside that would place it at risk for premature failure.



 	  Quote: 	
		    Do you think that the regulator is a bit wonky? Is the voltage too high? 

 Am I frying my battery? Is the overvoltage module overactive?


	


     About 150 years ago Lord Kelvin admonished us, ""If

     you can not measure it, you can not improve it." To

     craft considered answers to your questions, we'll need

     some numbers and some observations of behavior. I'll

     suggest that you craft the field voltage monitoring

     feature suggested in Figure Z-23.



     We need to know what the field voltage is in cruise

     RPM with minimum loads and with everything turned on.

     Also make note of voltage fluctuations during what

     should be a steady state condition (turn strobes on/off

     to see how much they added to any wiggles you observe).

     In particular, we'd like to capture field voltage

     behaviors leading up to a trip of the OV protection

     system.



     I know this can be tedious and difficult. This is

     why I own data acquisition systems that monitor and

     record real time values. If I had cash for all the

     Jet-A I've burned up waiting to capture a transient

     event in a sneaky failure I could pay off my mortgage.



     You're not frying anything. The bus voltage is

     not too high. It's unlikely that the OV protection

     system has become hyper-active with age. You don't

     say how long this regulator has been in service.



     Bob . . .

bicyclop(at)pacbell.net
Guest

Posted: Thu Jun 14, 2007 10:53 am Post subject: Regulator trouble?

The regulator has been in service for about 900 hrs. It's been through 

at least 2 or 3 Van's alternators in that time, though I don't have good 

records on that. I'll swing by radio shack and check back at a later 

date with field voltage info.



Thanks,



Ed



Robert L. Nuckolls, III wrote:



 	  Quote: 	
		   

 <nuckollsr(at)cox.net>



 At 09:31 PM 6/13/2007 -0800, you wrote:



> 

>

> Howdy,

>

> The other day, the low volt light started flashing and I found the 

> field breaker popped. This is an LR3C with the notorious Van's 35 amp 

> alternator. I reset the breaker and about 5 minutes later, it popped 

> again. The voltage had been running about 14.6 which seemed a little 

> much so I reset it and turned on some lights. The voltage ran about 

> 13.9 to 14 and the breaker didn't pop for quite a while. About the 

> time I thought that it was cool, the low volt light came on again, 

> but this time the breaker wasn't out. I turned off the master and 

> flew another hour and a half, including a stop for gas, and landed at 

> Aurora. I found a bit of hangar space and pulled the alternator. It 

> had a lot of end play and tested bad at the local auto parts place. I 

> bought another one at Van's - they tried to talk me out of it, but I 

> didn't want to rewire the airplane for the internally regulated unit 

> a long way from home. Hey, I would have happily spent the extra for 

> the B&C alternator, but I was in Aurora not Wichita.

>

> It charges just fine, in fact it'll hold voltage at idle with lights 

> on which is more than the old one would do. It is also running at 

> about 14.5 or .6 and the breaker has popped 3 times so far.

    You need to conduct and investigation of system performance

    as outlined in note 8 of



 http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf



    and take some readings. In fact, get an el-cheapo analog

    voltmeter for observing field voltage. It's more important

    to know how stable it is than to know the exact voltage reading.



>  The breaker resets and the alternator runs fine for a while, but I'm 

> wondering if I'll blow up the new alternator, too.

    No, I cannot think of any abuse (other than lack of cooling)

    that you could heap on an externally regulated alternator

    from outside that would place it at risk for premature failure.



>  Do you think that the regulator is a bit wonky? Is the voltage too 

> high? Am I frying my battery? Is the overvoltage module overactive?

     About 150 years ago Lord Kelvin admonished us, ""If

     you can not measure it, you can not improve it." To

     craft considered answers to your questions, we'll need

     some numbers and some observations of behavior. I'll

     suggest that you craft the field voltage monitoring

     feature suggested in Figure Z-23.



     We need to know what the field voltage is in cruise

     RPM with minimum loads and with everything turned on.

     Also make note of voltage fluctuations during what

     should be a steady state condition (turn strobes on/off

     to see how much they added to any wiggles you observe).

     In particular, we'd like to capture field voltage

     behaviors leading up to a trip of the OV protection

     system.



     I know this can be tedious and difficult. This is

     why I own data acquisition systems that monitor and

     record real time values. If I had cash for all the

     Jet-A I've burned up waiting to capture a transient

     event in a sneaky failure I could pay off my mortgage.



     You're not frying anything. The bus voltage is

     not too high. It's unlikely that the OV protection

     system has become hyper-active with age. You don't

     say how long this regulator has been in service.



     Bob . . .

bicyclop(at)pacbell.net
Guest

Posted: Sun Jun 17, 2007 6:12 pm Post subject: Regulator trouble?

I've got more info now, but I'm not sure what it means. I wired up a 

jack as per Bob's suggestion and can read field voltage on the VOM in 

flight. I also changed the setpoint on the regulator by about 1 turn on 

the adjustment screw. The downloaded installation instructions said that 

should be about 2 tenths of a volt. It had been running about 14.6. The 

regulator turns out to be an LR3B-14 not the C model I reported 

previously. I don't know how much difference that makes.



When started, the voltage ran right at 14.4, exactly as expected after 

the adjustment. The field was about 3.5 to 4.5 volts at idle. I'm using 

a digital VOM because it's what I have, so it jumps around a bit. With 

strobe, landing/taxi and position lights on and at idle, the buss came 

down to about 14.1 and the field rose to about 7 or 8 volts.  Load was 

around 17 amps by my meter.



In flight the numbers were pretty similar except that the buss never 

fell much below 14.4 no matter what I did with the lights. The field ran 

somewhere in the 4ish range with no lights and around 8 with. After 

about 30 minutes of flying, the buss was at 14.5. When I taxied in, it 

was 14.7 at idle which I don't understand at all. The field breaker did 

not blow today.



I'm in watch and wait mode for now.



Pax,



Ed Holyoke



Ed wrote:



 	  Quote: 	
		   



 The regulator has been in service for about 900 hrs. It's been through 

 at least 2 or 3 Van's alternators in that time, though I don't have 

 good records on that. I'll swing by radio shack and check back at a 

 later date with field voltage info.



 Thanks,



 Ed



 Robert L. Nuckolls, III wrote:



> 

> <nuckollsr(at)cox.net>

>

> At 09:31 PM 6/13/2007 -0800, you wrote:

>

>> 

>>

>> Howdy,

>>

>> The other day, the low volt light started flashing and I found the 

>> field breaker popped. This is an LR3C with the notorious Van's 35 

>> amp alternator. I reset the breaker and about 5 minutes later, it 

>> popped again. The voltage had been running about 14.6 which seemed a 

>> little much so I reset it and turned on some lights. The voltage ran 

>> about 13.9 to 14 and the breaker didn't pop for quite a while. About 

>> the time I thought that it was cool, the low volt light came on 

>> again, but this time the breaker wasn't out. I turned off the master 

>> and flew another hour and a half, including a stop for gas, and 

>> landed at Aurora. I found a bit of hangar space and pulled the 

>> alternator. It had a lot of end play and tested bad at the local 

>> auto parts place. I bought another one at Van's - they tried to talk 

>> me out of it, but I didn't want to rewire the airplane for the 

>> internally regulated unit a long way from home. Hey, I would have 

>> happily spent the extra for the B&C alternator, but I was in Aurora 

>> not Wichita.

>>

>> It charges just fine, in fact it'll hold voltage at idle with lights 

>> on which is more than the old one would do. It is also running at 

>> about 14.5 or .6 and the breaker has popped 3 times so far.

>

>    You need to conduct and investigation of system performance

>    as outlined in note 8 of

>

> http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf

>

>    and take some readings. In fact, get an el-cheapo analog

>    voltmeter for observing field voltage. It's more important

>    to know how stable it is than to know the exact voltage reading.

>

>>  The breaker resets and the alternator runs fine for a while, but 

>> I'm wondering if I'll blow up the new alternator, too.

>

>    No, I cannot think of any abuse (other than lack of cooling)

>    that you could heap on an externally regulated alternator

>    from outside that would place it at risk for premature failure.

>

>>  Do you think that the regulator is a bit wonky? Is the voltage too 

>> high? Am I frying my battery? Is the overvoltage module overactive?

>

>     About 150 years ago Lord Kelvin admonished us, ""If

>     you can not measure it, you can not improve it." To

>     craft considered answers to your questions, we'll need

>     some numbers and some observations of behavior. I'll

>     suggest that you craft the field voltage monitoring

>     feature suggested in Figure Z-23.

>

>     We need to know what the field voltage is in cruise

>     RPM with minimum loads and with everything turned on.

>     Also make note of voltage fluctuations during what

>     should be a steady state condition (turn strobes on/off

>     to see how much they added to any wiggles you observe).

>     In particular, we'd like to capture field voltage

>     behaviors leading up to a trip of the OV protection

>     system.

>

>     I know this can be tedious and difficult. This is

>     why I own data acquisition systems that monitor and

>     record real time values. If I had cash for all the

>     Jet-A I've burned up waiting to capture a transient

>     event in a sneaky failure I could pay off my mortgage.

>

>     You're not frying anything. The bus voltage is

>     not too high. It's unlikely that the OV protection

>     system has become hyper-active with age. You don't

>     say how long this regulator has been in service.

>

>     Bob . . .

pruemotorgliders(at)cox.n
Guest

Posted: Sun Jun 17, 2007 7:20 pm Post subject: Regulator trouble?

Gee Ed, I have no idea.  The only thought I have is to check in with 

B&C regarding the difference between Mod B and C.  That and a 

description of your history may lead to a understanding.



Hopefully the AeroElectric list will have some ideas

Jerry



On Jun 17, 2007, at 20:09, Ed wrote:



 	  Quote: 	
		   



 I've got more info now, but I'm not sure what it means. I wired up a 

 jack as per Bob's suggestion and can read field voltage on the VOM in 

 flight. I also changed the setpoint on the regulator by about 1 turn 

 on the adjustment screw. The downloaded installation instructions said 

 that should be about 2 tenths of a volt. It had been running about 

 14.6. The regulator turns out to be an LR3B-14 not the C model I 

 reported previously. I don't know how much difference that makes.



 When started, the voltage ran right at 14.4, exactly as expected after 

 the adjustment. The field was about 3.5 to 4.5 volts at idle. I'm 

 using a digital VOM because it's what I have, so it jumps around a 

 bit. With strobe, landing/taxi and position lights on and at idle, the 

 buss came down to about 14.1 and the field rose to about 7 or 8 volts. 

  Load was around 17 amps by my meter.



 In flight the numbers were pretty similar except that the buss never 

 fell much below 14.4 no matter what I did with the lights. The field 

 ran somewhere in the 4ish range with no lights and around 8 with. 

 After about 30 minutes of flying, the buss was at 14.5. When I taxied 

 in, it was 14.7 at idle which I don't understand at all. The field 

 breaker did not blow today.



 I'm in watch and wait mode for now.



 Pax,



 Ed Holyoke



 Ed wrote:



> 

>

> The regulator has been in service for about 900 hrs. It's been 

> through at least 2 or 3 Van's alternators in that time, though I 

> don't have good records on that. I'll swing by radio shack and check 

> back at a later date with field voltage info.

>

> Thanks,

>

> Ed

>

> Robert L. Nuckolls, III wrote:

>

>> 

>> <nuckollsr(at)cox.net>

>>

>> At 09:31 PM 6/13/2007 -0800, you wrote:

>>

>>> 

>>>

>>> Howdy,

>>>

>>> The other day, the low volt light started flashing and I found the 

>>> field breaker popped. This is an LR3C with the notorious Van's 35 

>>> amp alternator. I reset the breaker and about 5 minutes later, it 

>>> popped again. The voltage had been running about 14.6 which seemed 

>>> a little much so I reset it and turned on some lights. The voltage 

>>> ran about 13.9 to 14 and the breaker didn't pop for quite a while. 

>>> About the time I thought that it was cool, the low volt light came 

>>> on again, but this time the breaker wasn't out. I turned off the 

>>> master and flew another hour and a half, including a stop for gas, 

>>> and landed at Aurora. I found a bit of hangar space and pulled the 

>>> alternator. It had a lot of end play and tested bad at the local 

>>> auto parts place. I bought another one at Van's - they tried to 

>>> talk me out of it, but I didn't want to rewire the airplane for the 

>>> internally regulated unit a long way from home. Hey, I would have 

>>> happily spent the extra for the B&C alternator, but I was in Aurora 

>>> not Wichita.

>>>

>>> It charges just fine, in fact it'll hold voltage at idle with 

>>> lights on which is more than the old one would do. It is also 

>>> running at about 14.5 or .6 and the breaker has popped 3 times so 

>>> far.

>>

>>

>>

>>    You need to conduct and investigation of system performance

>>    as outlined in note 8 of

>>

>> http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf

>>

>>    and take some readings. In fact, get an el-cheapo analog

>>    voltmeter for observing field voltage. It's more important

>>    to know how stable it is than to know the exact voltage reading.

>>

>>

>>

>>>  The breaker resets and the alternator runs fine for a while, but 

>>> I'm wondering if I'll blow up the new alternator, too.

>>

>>

>>

>>    No, I cannot think of any abuse (other than lack of cooling)

>>    that you could heap on an externally regulated alternator

>>    from outside that would place it at risk for premature failure.

>>

>>>  Do you think that the regulator is a bit wonky? Is the voltage too 

>>> high? Am I frying my battery? Is the overvoltage module overactive?

>>

>>

>>

>>     About 150 years ago Lord Kelvin admonished us, ""If

>>     you can not measure it, you can not improve it." To

>>     craft considered answers to your questions, we'll need

>>     some numbers and some observations of behavior. I'll

>>     suggest that you craft the field voltage monitoring

>>     feature suggested in Figure Z-23.

>>

>>     We need to know what the field voltage is in cruise

>>     RPM with minimum loads and with everything turned on.

>>     Also make note of voltage fluctuations during what

>>     should be a steady state condition (turn strobes on/off

>>     to see how much they added to any wiggles you observe).

>>     In particular, we'd like to capture field voltage

>>     behaviors leading up to a trip of the OV protection

>>     system.

>>

>>     I know this can be tedious and difficult. This is

>>     why I own data acquisition systems that monitor and

>>     record real time values. If I had cash for all the

>>     Jet-A I've burned up waiting to capture a transient

>>     event in a sneaky failure I could pay off my mortgage.

>>

>>     You're not frying anything. The bus voltage is

>>     not too high. It's unlikely that the OV protection

>>     system has become hyper-active with age. You don't

>>     say how long this regulator has been in service.

>>

>>     Bob . . .

>>

>>

>>

>>

>>

>>

nuckollsr(at)cox.net
Guest

Posted: Mon Jun 18, 2007 6:10 am Post subject: Regulator trouble?

At 07:09 PM 6/17/2007 -0800, you wrote:



 	  Quote: 	
		  



I've got more info now, but I'm not sure what it means. I wired up a jack 

as per Bob's suggestion and can read field voltage on the VOM in flight. I 

also changed the setpoint on the regulator by about 1 turn on the 

adjustment screw. The downloaded installation instructions said that 

should be about 2 tenths of a volt. It had been running about 14.6. The 

regulator turns out to be an LR3B-14 not the C model I reported 

previously. I don't know how much difference that makes.



When started, the voltage ran right at 14.4, exactly as expected after the 

adjustment. The field was about 3.5 to 4.5 volts at idle. I'm using a 

digital VOM because it's what I have, so it jumps around a bit. With 

strobe, landing/taxi and position lights on and at idle, the buss came 

down to about 14.1 and the field rose to about 7 or 8 volts.  Load was 

around 17 amps by my meter.



In flight the numbers were pretty similar except that the buss never fell 

much below 14.4 no matter what I did with the lights. The field ran 

somewhere in the 4ish range with no lights and around 8 with. After about 

30 minutes of flying, the buss was at 14.5. When I taxied in, it was 14.7 

at idle which I don't understand at all. The field breaker did not blow today.



I'm in watch and wait mode for now.


	




   Excellent data! . . . and pretty much as expected. Let's review

   the significance:



   First, there are no differences between the B & C revisions of this

   regulator that would affect the phenomenon under investigation.



   (1) "With strobe, landing/taxi and position lights on and at idle,

        the buss came down to about 14.1 and the field rose to about

        7 or 8 volts."



        (a) The maximum possible range for field voltages is 0 to bus

        voltage . . . or a little below bus voltage because the

        pass transistor doesn't turn on with zero-volt drop. We

        would NEVER expect to see field voltage at ZERO during

        any set of normal operating conditions . . . ZERO field

        is ZERO output. The only time we would expect to see zero

        output is if something was broke.



        (b) The slight drop with load is within expectations.



        (c) The field voltage reading of 7-8 volts at idle tells us

        that your alternator's output is about half used up for

        this RPM and load conditions. As we noted above, the field

        cannot rise to more than about 14 volts and under the test

        conditions cited, you were already half way there.



    (2) "Load was around 17 amps by my meter."



        (a) Is this an alternator loadmeter? In other words, the 17A

        reading is the alternator output current for the conditions

        cited?



    (3) "In flight the numbers were pretty similar except that the

        buss never fell much below 14.4 no matter what I did with

        the lights."



        (a) Every regulator designer is pleased to hear this. The

        goal is to craft electronics that maintains the bus at the

        established set-point irrespective of load. So, for field

        voltages greater than zero and less than bus voltage, we would

        expect the bus voltage to stay put under any load that does

        not cause the field voltage to max out.



    (4) "The field ran somewhere in the 4ish range with no lights

        and around 8 with."



        (a) What size alternator is this? I think you mentioned a

        35A machine? Again, the reading of about 8 volts with loads

        on (and assuming the same 17A of output) that the alternator's

        output is about 1/2 used up.



     If this were my research project, I'd throw a little 200 samples

     per second data acquisition system (Snipe trap) on the field, bus

     volts and bus amps. Then I'd go fly the airplane and attempt to

     induce a trip by manipulation of controls for electrical system loads.



     Okay, your snipe catching sack is in hand and your flashlight

     (field volts indicator) is charged up. What we would hope to

     capture is what the field voltage is doing just prior and/or

     during a trip event. On the next flight, you'll want to "fiddle

     with the switches and things" while observing field voltage and

     see if you can induce a trip.



     The readings you've cited are strong indications that the system

     is/was performing as-designed during the period of your observations.



     Bob . . .

mprather(at)spro.net
Guest

Posted: Mon Jun 18, 2007 7:41 am Post subject: Regulator trouble?

If trying to induce a trip, maybe it would make sense to run the test

early in the morning when the OAT is low so as to help the alternator put

out maximum snort?  Does this regulator bump the voltage set point in

response to low temperature (temperature compensated)?

Regards,



Matt-



 	  Quote: 	
		   

 <nuckollsr(at)cox.net>



 At 07:09 PM 6/17/2007 -0800, you wrote:



>

>

>I've got more info now, but I'm not sure what it means. I wired up a jack

>as per Bob's suggestion and can read field voltage on the VOM in flight.

> I

>also changed the setpoint on the regulator by about 1 turn on the

>adjustment screw. The downloaded installation instructions said that

>should be about 2 tenths of a volt. It had been running about 14.6. The

>regulator turns out to be an LR3B-14 not the C model I reported

>previously. I don't know how much difference that makes.

>

>When started, the voltage ran right at 14.4, exactly as expected after

> the

>adjustment. The field was about 3.5 to 4.5 volts at idle. I'm using a

>digital VOM because it's what I have, so it jumps around a bit. With

>strobe, landing/taxi and position lights on and at idle, the buss came

>down to about 14.1 and the field rose to about 7 or 8 volts.  Load was

>around 17 amps by my meter.

>

>In flight the numbers were pretty similar except that the buss never fell

>much below 14.4 no matter what I did with the lights. The field ran

>somewhere in the 4ish range with no lights and around 8 with. After about

>30 minutes of flying, the buss was at 14.5. When I taxied in, it was 14.7

>at idle which I don't understand at all. The field breaker did not blow

> today.

>

>I'm in watch and wait mode for now.

    Excellent data! . . . and pretty much as expected. Let's review

    the significance:



    First, there are no differences between the B & C revisions of this

    regulator that would affect the phenomenon under investigation.



    (1) "With strobe, landing/taxi and position lights on and at idle,

         the buss came down to about 14.1 and the field rose to about

         7 or 8 volts."



         (a) The maximum possible range for field voltages is 0 to bus

         voltage . . . or a little below bus voltage because the

         pass transistor doesn't turn on with zero-volt drop. We

         would NEVER expect to see field voltage at ZERO during

         any set of normal operating conditions . . . ZERO field

         is ZERO output. The only time we would expect to see zero

         output is if something was broke.



         (b) The slight drop with load is within expectations.



         (c) The field voltage reading of 7-8 volts at idle tells us

         that your alternator's output is about half used up for

         this RPM and load conditions. As we noted above, the field

         cannot rise to more than about 14 volts and under the test

         conditions cited, you were already half way there.



     (2) "Load was around 17 amps by my meter."



         (a) Is this an alternator loadmeter? In other words, the 17A

         reading is the alternator output current for the conditions

         cited?



     (3) "In flight the numbers were pretty similar except that the

         buss never fell much below 14.4 no matter what I did with

         the lights."



         (a) Every regulator designer is pleased to hear this. The

         goal is to craft electronics that maintains the bus at the

         established set-point irrespective of load. So, for field

         voltages greater than zero and less than bus voltage, we would

         expect the bus voltage to stay put under any load that does

         not cause the field voltage to max out.



     (4) "The field ran somewhere in the 4ish range with no lights

         and around 8 with."



         (a) What size alternator is this? I think you mentioned a

         35A machine? Again, the reading of about 8 volts with loads

         on (and assuming the same 17A of output) that the alternator's

         output is about 1/2 used up.



      If this were my research project, I'd throw a little 200 samples

      per second data acquisition system (Snipe trap) on the field, bus

      volts and bus amps. Then I'd go fly the airplane and attempt to

      induce a trip by manipulation of controls for electrical system

 loads.



      Okay, your snipe catching sack is in hand and your flashlight

      (field volts indicator) is charged up. What we would hope to

      capture is what the field voltage is doing just prior and/or

      during a trip event. On the next flight, you'll want to "fiddle

      with the switches and things" while observing field voltage and

      see if you can induce a trip.



      The readings you've cited are strong indications that the system

      is/was performing as-designed during the period of your observations.



      Bob . . .

klehman(at)albedo.net
Guest

Posted: Mon Jun 18, 2007 8:25 am Post subject: Regulator trouble?

I have a slightly different take on this as it seems there might already 

be some clues here.



Shouldn't the field voltage go above 8 volts when the alternator is 

loaded on the ground. If it is putting out less that 14.4 volts at low 

rpm - why isn't the field voltage up around 12 or 13? High resistance 

somewhere in the field?



Next I'd want to know why 14.7 volts while taxiing in.  Is the regulator 

voltage going up when it is hot? Does it not throttle back far enough 

under light load?  Is there a connection that is high resistance when 

hot such that the regulator is sensing 14.4 but putting out 14.7 

upstream where the voltmeter is located? Or is it an inaccurate voltmeter?



If the connections have already been checked, I'd be tempted to 

temporarilly wire in a cheap regulator and see what happens.



Ken



Robert L. Nuckolls, III wrote:



 	  Quote: 	
		   

 <nuckollsr(at)cox.net>



 At 07:09 PM 6/17/2007 -0800, you wrote:



> 

>

> I've got more info now, but I'm not sure what it means. I wired up a 

> jack as per Bob's suggestion and can read field voltage on the VOM in 

> flight. I also changed the setpoint on the regulator by about 1 turn 

> on the adjustment screw. The downloaded installation instructions 

> said that should be about 2 tenths of a volt. It had been running 

> about 14.6. The regulator turns out to be an LR3B-14 not the C model 

> I reported previously. I don't know how much difference that makes.

>

> When started, the voltage ran right at 14.4, exactly as expected 

> after the adjustment. The field was about 3.5 to 4.5 volts at idle. 

> I'm using a digital VOM because it's what I have, so it jumps around 

> a bit. With strobe, landing/taxi and position lights on and at idle, 

> the buss came down to about 14.1 and the field rose to about 7 or 8 

> volts.  Load was around 17 amps by my meter.

>

> In flight the numbers were pretty similar except that the buss never 

> fell much below 14.4 no matter what I did with the lights. The field 

> ran somewhere in the 4ish range with no lights and around 8 with. 

> After about 30 minutes of flying, the buss was at 14.5. When I taxied 

> in, it was 14.7 at idle which I don't understand at all. The field 

> breaker did not blow today.

>

> I'm in watch and wait mode for now.



   Excellent data! . . . and pretty much as expected. Let's review

   the significance:



   First, there are no differences between the B & C revisions of this

   regulator that would affect the phenomenon under investigation.



   (1) "With strobe, landing/taxi and position lights on and at idle,

        the buss came down to about 14.1 and the field rose to about

        7 or 8 volts."



        (a) The maximum possible range for field voltages is 0 to bus

        voltage . . . or a little below bus voltage because the

        pass transistor doesn't turn on with zero-volt drop. We

        would NEVER expect to see field voltage at ZERO during

        any set of normal operating conditions . . . ZERO field

        is ZERO output. The only time we would expect to see zero

        output is if something was broke.



        (b) The slight drop with load is within expectations.



        (c) The field voltage reading of 7-8 volts at idle tells us

        that your alternator's output is about half used up for

        this RPM and load conditions. As we noted above, the field

        cannot rise to more than about 14 volts and under the test

        conditions cited, you were already half way there.



    (2) "Load was around 17 amps by my meter."



        (a) Is this an alternator loadmeter? In other words, the 17A

        reading is the alternator output current for the conditions

        cited?



    (3) "In flight the numbers were pretty similar except that the

        buss never fell much below 14.4 no matter what I did with

        the lights."



        (a) Every regulator designer is pleased to hear this. The

        goal is to craft electronics that maintains the bus at the

        established set-point irrespective of load. So, for field

        voltages greater than zero and less than bus voltage, we would

        expect the bus voltage to stay put under any load that does

        not cause the field voltage to max out.



    (4) "The field ran somewhere in the 4ish range with no lights

        and around 8 with."



        (a) What size alternator is this? I think you mentioned a

        35A machine? Again, the reading of about 8 volts with loads

        on (and assuming the same 17A of output) that the alternator's

        output is about 1/2 used up.



     If this were my research project, I'd throw a little 200 samples

     per second data acquisition system (Snipe trap) on the field, bus

     volts and bus amps. Then I'd go fly the airplane and attempt to

     induce a trip by manipulation of controls for electrical system 

 loads.



     Okay, your snipe catching sack is in hand and your flashlight

     (field volts indicator) is charged up. What we would hope to

     capture is what the field voltage is doing just prior and/or

     during a trip event. On the next flight, you'll want to "fiddle

     with the switches and things" while observing field voltage and

     see if you can induce a trip.



     The readings you've cited are strong indications that the system

     is/was performing as-designed during the period of your observations.



     Bob . . .

nuckollsr(at)cox.net
Guest

Posted: Mon Jun 18, 2007 5:24 pm Post subject: Regulator trouble?

At 09:33 AM 6/18/2007 -0600, you wrote:



 	  Quote: 	
		  



If trying to induce a trip, maybe it would make sense to run the test

early in the morning when the OAT is low so as to help the alternator put

out maximum snort?  Does this regulator bump the voltage set point in

response to low temperature (temperature compensated)?


	


   The regulator is not compensated for battery ambient. It

   is compensated for a close to zero temperature coefficient

   as practical.



   Ed also noted that the system tripped several times while

   in cruising flight so it seems a low-order probability

   that a first start of the day "cold test" would be any

   more revealing.



   Actually, given the numbers that Ed has cited, I'm

   pretty much convinced that "catching" his Snipe is

   going to be pretty tough with just a digital voltmeter.

   The best we might hope for is that the field voltage

   becomes jittery just before a nuisance trip when it

   had been stable earlier.



   Ed, you might consider getting an el-cheapo analog

   meter from Radio Shack. See:



   http://tinyurl.com/29yk5d



   This instrument has a 15 volt DC range that is ideal

   for this investigation. Right now, we're going to be

   more interested in dynamics (steady vs. twitchy) as

   opposed to knowing the actual reading.



   In the mean time, my software guru is looking into

   how hard it would be to do a quick turn on a little

   4-channel, data acquisition system that would run off

   a laptop. Ed, do you have a laptop computer you could

   press into the service of Snipe Catching?



   Bob . . .

aadamson(at)highrf.com
Guest

Posted: Mon Jun 18, 2007 5:47 pm Post subject: Regulator trouble?

Bob, not sure they get much cheaper than this 



http://www.dataq.com/products/startkit/di194rs.htm



They also have them for USB, but not sure of the cost... Also 12Bit version

are available.



Alan 



--

aadamson(at)highrf.com
Guest

Posted: Mon Jun 18, 2007 5:49 pm Post subject: Regulator trouble?

Here's the USB 10 bit version

http://www.dataq.com/products/startkit/di148.htm

And the USB 12 bit version http://www.dataq.com/products/startkit/di158.htm



Hope this helps... Still way cheaper than spending the time/effort to build

one and write the software.



Alan 



--

nuckollsr(at)cox.net
Guest

Posted: Mon Jun 18, 2007 7:17 pm Post subject: Regulator trouble?

At 12:18 PM 6/18/2007 -0400, you wrote:



 	  Quote: 	
		  



I have a slightly different take on this as it seems there might already 

be some clues here.



Shouldn't the field voltage go above 8 volts when the alternator is loaded 

on the ground. If it is putting out less that 14.4 volts at low rpm - why 

isn't the field voltage up around 12 or 13? High resistance somewhere in 

the field?


	


   The voltage will go that high only if one approaches the alternator's

   maximum available output current for that RPM. In this case, he cites

   a 17A load and ramp idle RPM.



 	  Quote: 	
		  Next I'd want to know why 14.7 volts while taxiing in.  Is the regulator 

voltage going up when it is hot? Does it not throttle back far enough 

under light load?  Is there a connection that is high resistance when hot 

such that the regulator is sensing 14.4 but putting out 14.7 upstream 

where the voltmeter is located? Or is it an inaccurate voltmeter?


	


   There's a ton of variables which can stack up to push the setpoint

   around a bit . . . what we're interested in finding is an instability

   that accounts for the nuisance trip of an OV protection system set to

   operate at 16.2 volts or so.

 	  Quote: 	
		  If the connections have already been checked, I'd be tempted to 

temporarilly wire in a cheap regulator and see what happens.


	


   A cheap regulator wouldn't have the ov protection built in. It

   WOULD be a useful experiment to temporarily wire in a substitute

   regulator and a separate OV sensor. I think I've got some hardware

   laying around we can send him if we don't see something really

   profound . . . or he's unable to observe a field and bus voltage

   surge associated with the nuisance trip.



   Bob . . .

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