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VM-1000 current sensor question

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dean.psiropoulos(at)veriz
Guest

Posted: Thu Jul 06, 2006 9:46 pm Post subject: VM-1000 current sensor question

I've been looking at this VM1000 current sensor (it looks like some sort of

hall effect sensor with 4 terminals, it's a coil you slide over the wire, no

connection needed). Originally I had it on the feed line from the alternator

but realized that I would only get readings of zero and greater than zero on

the display if I did that.  So I thought I'd put it around the fat wire that

connects to the battery positive terminal and get both discharge and charge

readings.  But....re-reading the VM-1000 manual and looking at their display

silk-screening, it appears that the display is only designed to read a

positive rate of charge from the alternator (0 to +60 amps).  I don't have

everything connected yet so I can't actually fire it up and test it.  



You VM1000 users, is this true?  Does it NOT read and display negative

amperes when the battery is discharging and the alternator is not running

(or failed)?  Is everyone installing this sensor on the alternator feed line

or are some of you doing something else??? if so what???? and why?  Thanks.

Dean Psiropoulos

RV-6A N197DM

Plodding along to blissful completion.

recapen(at)earthlink.net
Guest

Posted: Fri Jul 07, 2006 3:01 am Post subject: VM-1000 current sensor question

I'm in a similar situation as Dean - except I have most of my electrical 

system up and functioning.  My amp sensor is in the equivalent place of the 

feed line and could only show current being generated by the alternators. 

My instruction manual shows the 'minus' bar on the display page implying 

that the unit could display current draw and supply - but I can't figure out 

how to wire it so both situations would be discernable to the 

transducer......the only solutions that I have come up with involve A) two 

wires passing throught the transducer - one 'flowing' in each 

direction...under normal operation one would carry generated current - under 

failure operation (of the alternators) the other would carry drawn current 

or B) two transducers with a switch to select which one is being 

displayed...one transducer would show the generated current and the other 

would show drawn current.



The VM1000 instruction manual indicates that the transducer is to be placed 

to measure generated current from what I remember reading and does not 

provide for reading of drawn current - even though the unit is implied to be 

able to display either mode.



Maybe we need to get Vision Microsystems to weigh in n this one.....I'll 

send out a note to them.....



Ralph Capen

---

jlinga(at)mchsi.com
Guest

Posted: Fri Jul 07, 2006 4:27 am Post subject: VM-1000 current sensor question

Guys,

     When I installed my VM1000C, I  had the same question and called the company.  The display will not show  negative numbers.  The current sensor is designed to be used as a loadmeter  and not a battery ammeter.  The voltage will generally give you a good  indication whether or not the battery is charging.

  

 Jerry

  

  

 --> AeroElectric-List message posted by: "Ralph E.  Capen" <recapen(at)earthlink.net ([email]recapen(at)earthlink.net?subject=Re:%20VM-1000%20current%20sensor%20question&replyto=003801c6a1b2$0a00a8c0(at)CAPENFAMILY.ORG[/email])>



I'm  in a similar situation as Dean - except I have most of my electrical 

system  up and functioning.  My amp sensor is in the equivalent place of the  

feed line and could only show current being generated by the alternators.  

My instruction manual shows the 'minus' bar on the display page implying  

that the unit could display current draw and supply - but I can't figure out  

how to wire it so both situations would be discernable to the  

transducer......the only solutions that I have come up with involve A) two  

wires passing throught the transducer - one 'flowing' in each  

direction...under normal operation one would carry generated current - under  

failure operation (of the alternators) the other would carry drawn current  

or B) two transducers with a switch to select which one is being  

displayed...one transducer would show the generated current and the other  

would show drawn current.



The VM1000 instruction manual indicates  that the transducer is to be placed 

to measure generated current from what I  remember reading and does not 

provide for reading of drawn current - even  though the unit is implied to be 

able to display either mode.



Maybe  we need to get Vision Microsystems to weigh in n this one.....I'll 

send out  a note to them.....



Ralph Capen

---

nuckollsr(at)cox.net
Guest

Posted: Fri Jul 07, 2006 5:19 am Post subject: VM-1000 current sensor question

At 01:43 AM 7/7/2006 -0400, you wrote:



 	  Quote: 	
		  

<dean.psiropoulos(at)verizon.net>



I've been looking at this VM1000 current sensor (it looks like some sort of

hall effect sensor with 4 terminals, it's a coil you slide over the wire, no

connection needed). Originally I had it on the feed line from the alternator

but realized that I would only get readings of zero and greater than zero on

the display if I did that.


	


   Correct. It becomes an alternator LOADMETER

 	  Quote: 	
		    . . . So I thought I'd put it around the fat wire that

connects to the battery positive terminal and get both discharge and charge

readings.


	


   That becomes a BATTERY AMMETER which is less useful. While

   it was the ONLY instrumentation in most automobiles and many

   airplanes, it wasa system health instrument that required

   interpretation and flight to flight trend monitoring. It met

   FAA requirements for electrical system health monitoring.



   The problem with a battery ammeter is that it "sorta" tells you if

   the bus voltage is okay when the recharge current ultimately goes

   back to zero AFTER it sorta tells you that the battery is okay when

   it accepts a healthy recharge after engine start. Battery ammeters

   are better than nothing but not much. Given that  the VM-1000 provides

   voltage readings and low volts warning, then using the ammeter function

   to watch alternator load is the most definitive use of the instrument

   for troubleshooting.

        Bob . . .

      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

bakerocb

Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA

Posted: Fri Jul 07, 2006 7:34 am Post subject: VM-1000 current sensor question

7/7/2006



Responding to an AeroElectric-List message previously posted by: "DEAN 

PSIROPOULOS" <dean.psiropoulos(at)verizon.net>



Hello Dean, Why don't you just shoot an email to Vision Microsystems 

support(at)visionmicrosystems.com <support(at)visionmicrosystems.com> or, better 

yet, call them on the phone, (360-714-8203) ask for a technician and ask 

him. I have found them great people to deal with. Please tell us what you 

learn.



My sensor is on the output (B lead) from the alternator. My visual 

electrical information consists of that VM 1000 display reading of amperage 

being put out by the alternator, the VM 1000 display of bus voltage, and a 

low voltage warning light from a B&C LR3 voltage regulator. The VM 1000 

display amperage reading is zero until the alternator comes on line.



Isn't the above a sufficient display of electrical information?



I guess it would be nice to be able to know at all times what amount of the 

electrical supply to the aircraft systems was coming from the battery and 

what amount was coming from the alternator, but I don't know just exactly 

how one would go about configuring a system to obtain that information or 

how one would use that information.



I think that after the engine is started and the alternator is on line that 

all of the aircraft's electrical system needs are being supplied by the 

alternator and if the battery needs charging as determined by the voltage 

regulator then the alternator is also supplying the amperage that flows into 

the battery.The only time the battery should be discharging is if the total 

amperage required by aircraft systems and battery charging needs is greater 

than the output capacity of the alternator. Can some one help me here?



OC



PS: I did find the VM hall effect sensor difficult to mount. Their 

directions to put it into some sort of protective box was too awkward for me 

so mine is just bolted to a bracket on the forward side of the fire wall. 

Has worked OK for 144 hours.



"DEAN PSIROPOULOS WRITES"



 	  Quote: 	
		   I've been looking at this VM1000 current sensor (it looks like some sort 

 of

 hall effect sensor with 4 terminals, it's a coil you slide over the wire, 

 no

 connection needed). Originally I had it on the feed line from the 

 alternator

 but realized that I would only get readings of zero and greater than zero 

 on

 the display if I did that.  So I thought I'd put it around the fat wire 

 that

 connects to the battery positive terminal and get both discharge and 

 charge

 readings.  But....re-reading the VM-1000 manual and looking at their 

 display

 silk-screening, it appears that the display is only designed to read a

 positive rate of charge from the alternator (0 to +60 amps).  I don't have

 everything connected yet so I can't actually fire it up and test it.



 You VM1000 users, is this true?  Does it NOT read and display negative

 amperes when the battery is discharging and the alternator is not running

 (or failed)?  Is everyone installing this sensor on the alternator feed 

 line

 or are some of you doing something else??? if so what???? and why? 

 Thanks.

 Dean Psiropoulos

 RV-6A N197DM

 Plodding along to blissful completion.

recapen(at)earthlink.net
Guest

Posted: Fri Jul 07, 2006 8:42 am Post subject: VM-1000 current sensor question

I sent a note to Vision Microsystems....



I'll post the response.....



BTW, My understanding matches yours....about the alternator supplying required current etc.....



Ralph

--

flyboy.bob(at)gmail.com
Guest

Posted: Fri Jul 07, 2006 2:00 pm Post subject: VM-1000 current sensor question

So Bob,



I hope this isn't too redundant, in this scenario, where is the best

(most useful) place to locate the hall effect sensor?



Thanks,

Bob Christensen

in SE Iowa - RV-8 Bldr

On 7/7/06, Robert L. Nuckolls, III <nuckollsr(at)cox.net> wrote:

 	  Quote: 	
		   



 At 01:43 AM 7/7/2006 -0400, you wrote:



 >

 ><dean.psiropoulos(at)verizon.net>

 >

 >I've been looking at this VM1000 current sensor (it looks like some sort of

 >hall effect sensor with 4 terminals, it's a coil you slide over the wire, no

 >connection needed). Originally I had it on the feed line from the alternator

 >but realized that I would only get readings of zero and greater than zero on

 >the display if I did that.



   Correct. It becomes an alternator LOADMETER

 >  . . . So I thought I'd put it around the fat wire that

 >connects to the battery positive terminal and get both discharge and charge

 >readings.



   That becomes a BATTERY AMMETER which is less useful. While

   it was the ONLY instrumentation in most automobiles and many

   airplanes, it wasa system health instrument that required

   interpretation and flight to flight trend monitoring. It met

   FAA requirements for electrical system health monitoring.



   The problem with a battery ammeter is that it "sorta" tells you if

   the bus voltage is okay when the recharge current ultimately goes

   back to zero AFTER it sorta tells you that the battery is okay when

   it accepts a healthy recharge after engine start. Battery ammeters

   are better than nothing but not much. Given that  the VM-1000 provides

   voltage readings and low volts warning, then using the ammeter function

   to watch alternator load is the most definitive use of the instrument

   for troubleshooting.

        Bob . . .

      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

nuckollsr(at)cox.net
Guest

Posted: Fri Jul 07, 2006 2:42 pm Post subject: VM-1000 current sensor question

At 04:54 PM 7/7/2006 -0500, you wrote:



 	  Quote: 	
		  



So Bob,



I hope this isn't too redundant, in this scenario, where is the best

(most useful) place to locate the hall effect sensor?



Thanks,

Bob Christensen

in SE Iowa - RV-8 Bldr


	


    If it were my airplane (and I chose to have any ammeters

    at all) they would be alternator loadmeters. This is the

    most useful current measurement location for troubleshooting

    a misbehaving alternator system.



    Bob . . .

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Fri Jul 07, 2006 4:03 pm Post subject: VM-1000 current sensor question

On Jul 7, 2006, at 5:54 PM, Bob C. wrote:



 	  Quote: 	
		   

 <flyboy.bob(at)gmail.com>



 So Bob,



 I hope this isn't too redundant, in this scenario, where is the best

 (most useful) place to locate the hall effect sensor?


	


In the average electrical system there are three places to measure  

current. If measure two you can calculate the third. The three places  

are:



1. output of the alternator (B-lead);



2. battery positive terminal;



3. input to the main distribution bus.



If you know what is coming out of the alternator and what is going  

into the loads then the difference is what is going into or coming  

out of the battery.



If you know what is coming out of the alternator and what is going  

into the battery, the difference is going into your loads.



If you know what is going into the battery and what is going into  

your loads, add them together to figure out alternator load.



If I could only measure one I would measure alternator load and, of  

course, system voltage. You will quickly learn what your loads draw  

and what the battery draws will drop near to zero. Any excess load on  

the alternator indicates a problem.



Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery

nuckollsr(at)cox.net
Guest

Posted: Mon Jul 10, 2006 11:29 am Post subject: VM-1000 current sensor question

This conversation has run far-afield . . .



Consider that as long as your low-volts warning light is OFF,

there is nothing helpful for aviating or navigating offered by any

display of amps in any part of the system. When the low volts

light does come on, it's wise to have "plan-b" in the hip pocket

for comfortable termination of flight, preferably at the airport

of intended destination. Again, whatever the amps display is saying

is not useful to the task at hand.



When it comes time to troubleshoot the system, there is no

single measurement point for amps that will minimize the efforts

needed to troubleshoot the system. The repair task almost always

requires probing the system for a LOT more data than what is

offered by panel displays.



I'll suggest there is no right, better, wrong, or best place to

put an ammeter sense point. Every one of the classic locations offers

some data that is useful only if you know the significance of the

data and how to interpret it. But using any such data in flight

for diagnosis is not a useful thing to do . . . it's never helpful

for comfortably completing the flight. No matter where you choose

to put the sense point(s), they will be only the beginning of a

future troubleshooting effort.



Bob . . .

AdventureD

Joined: 13 Jan 2021
Posts: 16

Posted: Wed Mar 10, 2021 11:37 am Post subject: Re: VM-1000 current sensor question

Resurrecting this old thread.  



Suppose the hall effect sensor is on the fat wire from battery 2 in Z-14 with a 70 amp alternator 1 and a 20 amp alternator 2.  Here are my questions (recognizing that this is not debugging done in the airplane -- its for understanding how this stuff works).



1. Under normal conditions, when both alternators and batteries are on and the crossfeed is not closed, what will the gauge connected to the hall effect sensor show?  Will it show the voltage of the #2 battery and zero amps since the current on the number 2 bus is being drawn from the alternator rather than from the battery?  Something else?



2. Suppose the #2 alternator craps out and the low voltage light comes on.  If I shut down the #2 alternator and leave the crossfeed open, what will the gauge show?  Will it show the same voltage for the #2 battery and the current draw of the instruments on the #2 bus?  Something else?



3. Suppose I close the cross feed contactor after the #2 alternator goes kaput and is shut down.  Does the gauge now show the voltage of the #2 battery and zero current if the #1 alternator is sufficient to supply both buses?



4. Suppose I shut down both alternators, turn on both batteries, and close the crossfeed.  Since battery 1 and battery 2 are now connected, what will the gauge show?  



This is all by way of trying to understand what these volts/amps meters do.

user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Wed Mar 10, 2021 4:39 pm Post subject: Re: VM-1000 current sensor question

Hall effect sensors only measure current, not voltage.

If the hall effect sensor is located to measure current into or out of a battery,

then once the battery is recharged, the current into the battery will be near zero.

If the hall effect sensor is located to measure alternator output current, the 

ammeter will show the combination of aircraft load current and battery recharge current.

If the hall effect sensor is located to measure aircraft load current, then it will 

not be known if that current is coming from the battery or from an alternator.

Some builders elect to not install an ammeter.  As long as the voltage is above 

13.5 VDC, then the alternator must be working.

_________________
Joe Gores

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