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Current Sensor basic question

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donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Sat Jul 09, 2016 11:34 am Post subject: Current Sensor basic question

I'm using the 50a hall effect sensor which came with my Grand Rapids EIS 6000.  But the current numbers don't jibe with the VPX. It's not a huge difference, but enough that I don't like it. 

 

I've talked with GRT and verified the offset and scale factor configuration but it's still not right.

 

While searching to see if anyone else was having this issue I ran across an aftermarket sensor.

 

High accuracy current sensor

http://www.crazedpilot.com/high-accuracy-current-sensor-for-5v-input-7-30v-supply-engine-monitor-systems-dynon-mgl-grand-rapids-garmin-and-more-ems-efis-systems/ 



Interestingly, it looks just like the GRT sensor.

 

I contacted them to make sure it would work with the EIS6000 and if it came with the offset and scale factor values that needed to be configured on the EIS. They said yes and that the correct values were based on the wire size being used.  There is nothing in the GRT documentation about the wire size having an effect on the offset and scale factor settings.

 

Is it true that the size of the wire effects the reading of a hall effect sensor?

 

Don

yellowduckduo(at)gmail.co
Guest

Posted: Sat Jul 09, 2016 11:52 am Post subject: Current Sensor basic question

I can believe that wire size affects that sensor but not the hollow 

round 60 amp sensor that GRT sold me several years ago.

The wonderful thing about the GRT sensor is that you can adjust the 

offset and scale for almost any sensor.  IMO the values from GRT are 

simply a recommended starting value and all of my sensors benefited from 

some tweaking when I calibrated them.

Ken



On 09/07/2016 3:34 PM, donjohnston wrote:

 	  Quote: 	
		   



 I'm using the 50a hall effect sensor which came with my Grand Rapids EIS 6000.  But the current numbers don't jibe with the VPX. It's not a huge difference, but enough that I don't like it.

   

 I've talked with GRT and verified the offset and scale factor configuration but it's still not right.

   

 While searching to see if anyone else was having this issue I ran across an aftermarket sensor.

   

 High accuracy current sensor

 http://www.crazedpilot.com/high-accuracy-current-sensor-for-5v-input-7-30v-supply-engine-monitor-systems-dynon-mgl-grand-rapids-garmin-and-more-ems-efis-systems/



 Interestingly, it looks just like the GRT sensor.

   

 I contacted them to make sure it would work with the EIS6000 and if it came with the offset and scale factor values that needed to be configured on the EIS. They said yes and that the correct values were based on the wire size being used.  There is nothing in the GRT documentation about the wire size having an effect on the offset and scale factor settings.

   

 Is it true that the size of the wire effects the reading of a hall effect sensor?

   

 Don





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=457996#457996

billp(at)wwpc.com
Guest

Posted: Sat Jul 09, 2016 12:32 pm Post subject: Current Sensor basic question

If it's a Hall Effect sensor the wire size doesn't matter. Magnetic 

field is what the Hall Effect device is measuring. What dictates the 

magnetic field strength is Ampere-Turns. I assume you have the wire only 

passing through the sensor once (one turn).



A smaller wire will have more voltage drop across it for any given 

current flow than a larger one, but won't change the current measurement.



Look at your installation. If the wire and the sensor is laying tightly 

with other wires, the field may be effected. This should be a very 

localized effect so if you have about 1/2" from other wires carrying 

current you should be OK.



Bill Putney - WB6RFW

Chief Engineer

KPTZ - Port Townsend, WA



PP-SEL/A&P-IA



"...you know me to be a very smart man. Don't you think if I were wrong, I'd know it?" -Sheldon Cooper



On 7/9/16 12:34 PM, donjohnston wrote:

 	  Quote: 	
		   



 I'm using the 50a hall effect sensor which came with my Grand Rapids EIS 6000.  But the current numbers don't jibe with the VPX. It's not a huge difference, but enough that I don't like it.

   

 I've talked with GRT and verified the offset and scale factor configuration but it's still not right.

   

 While searching to see if anyone else was having this issue I ran across an aftermarket sensor.

   

 High accuracy current sensor

 http://www.crazedpilot.com/high-accuracy-current-sensor-for-5v-input-7-30v-supply-engine-monitor-systems-dynon-mgl-grand-rapids-garmin-and-more-ems-efis-systems/



 Interestingly, it looks just like the GRT sensor.

   

 I contacted them to make sure it would work with the EIS6000 and if it came with the offset and scale factor values that needed to be configured on the EIS. They said yes and that the correct values were based on the wire size being used.  There is nothing in the GRT documentation about the wire size having an effect on the offset and scale factor settings.

   

 Is it true that the size of the wire effects the reading of a hall effect sensor?

   

 Don





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=457996#457996

enginerdy(at)gmail.com
Guest

Posted: Sat Jul 09, 2016 12:43 pm Post subject: Current Sensor basic question

In general that is 100% correct, but this sensor doesn’t appear to have a split ring to concentrate the magnetic field into a Hall sensor.

When you’re not collecting the whole field, geometry has a large effect on field strength.

I’m curious how this sensor works or if they expect some sort of calibration step after installation.

 	  Quote: 	
		   On Jul 9, 2016, at 3:29 PM, Bill Putney <billp(at)wwpc.com> wrote:

 If it's a Hall Effect sensor the wire size doesn't matter. Magnetic field is what the Hall Effect device is measuring. What dictates the magnetic field strength is Ampere-Turns. I assume you have the wire only passing through the sensor once (one turn).

 A smaller wire will have more voltage drop across it for any given current flow than a larger one, but won't change the current measurement.

 Look at your installation. If the wire and the sensor is laying tightly with other wires, the field may be effected. This should be a very localized effect so if you have about 1/2" from other wires carrying current you should be OK.

 Bill Putney - WB6RFW

 Chief Engineer

 KPTZ - Port Townsend, WA

 PP-SEL/A&P-IA

 "...you know me to be a very smart man. Don't you think if I were wrong, I'd know it?" -Sheldon Cooper

 On 7/9/16 12:34 PM, donjohnston wrote:

> 

> 

> I'm using the 50a hall effect sensor which came with my Grand Rapids EIS 6000.  But the current numbers don't jibe with the VPX. It's not a huge difference, but enough that I don't like it.

>  I've talked with GRT and verified the offset and scale factor configuration but it's still not right.

>  While searching to see if anyone else was having this issue I ran across an aftermarket sensor.

>  High accuracy current sensor

> http://www.crazedpilot.com/high-accuracy-current-sensor-for-5v-input-7-30v-supply-engine-monitor-systems-dynon-mgl-grand-rapids-garmin-and-more-ems-efis-systems/

> 

> Interestingly, it looks just like the GRT sensor.

>  I contacted them to make sure it would work with the EIS6000 and if it came with the offset and scale factor values that needed to be configured on the EIS. They said yes and that the correct values were based on the wire size being used.  There is nothing in the GRT documentation about the wire size having an effect on the offset and scale factor settings.

>  Is it true that the size of the wire effects the reading of a hall effect sensor?

>  Don

> 

> 

> 

> 

> Read this topic online here:

> 

> http://forums.matronics.com/viewtopic.php?p=457996#457996

> 

> 

> 

> 

> 

> 

> 

> 

> 

>

alec(at)alecmyers.com
Guest

Posted: Sat Jul 09, 2016 12:46 pm Post subject: Current Sensor basic question

It appears from the photograph that it's sensing the magnetic field at only one or two points; The field decays in strength with distance away from the conductor, and measured at the surface surface a larger conductor has a smaller field than a small conductor carrying the same current (because of the 1/r rule) so I would expect the size of the conductor to make a difference.



If the current sensor were a transformer (which effectively integrates the field strength around a closed loop surrounding the conductor)  then no, the size of the conductor wouldn't make a difference; but this doesn't appear to be such a thing. Of course a transformer wouldn't be able to detect a DC current so you'd have to be doing something very smart like integrating the transformer output which would be expensive, and probably inaccurate.






If it's a Hall Effect sensor the wire size doesn't matter. Magnetic field is what the Hall Effect device is measuring. What dictates the magnetic field strength is Ampere-Turns. I assume you have the wire only passing through the sensor once (one turn).



A smaller wire will have more voltage drop across it for any given current flow than a larger one, but won't change the current measurement.



Look at your installation. If the wire and the sensor is laying tightly with other wires, the field may be effected. This should be a very localized effect so if you have about 1/2" from other wires carrying current you should be OK.



Bill Putney - WB6RFW

Chief Engineer

KPTZ - Port Townsend, WA



PP-SEL/A&P-IA



"...you know me to be a very smart man. Don't you think if I were wrong, I'd know it?" -Sheldon Cooper



On 7/9/16 12:34 PM, donjohnston wrote:

 	  Quote: 	
		   

 

 I'm using the 50a hall effect sensor which came with my Grand Rapids EIS 6000.  But the current numbers don't jibe with the VPX. It's not a huge difference, but enough that I don't like it.

  I've talked with GRT and verified the offset and scale factor configuration but it's still not right.

  While searching to see if anyone else was having this issue I ran across an aftermarket sensor.

  High accuracy current sensor

 http://www.crazedpilot.com/high-accuracy-current-sensor-for-5v-input-7-30v-supply-engine-monitor-systems-dynon-mgl-grand-rapids-garmin-and-more-ems-efis-systems/

 

 Interestingly, it looks just like the GRT sensor.

  I contacted them to make sure it would work with the EIS6000 and if it came with the offset and scale factor values that needed to be configured on the EIS. They said yes and that the correct values were based on the wire size being used.  There is nothing in the GRT documentation about the wire size having an effect on the offset and scale factor settings.

  Is it true that the size of the wire effects the reading of a hall effect sensor?

  Don

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=457996#457996

yellowduckduo(at)gmail.co
Guest

Posted: Sat Jul 09, 2016 1:00 pm Post subject: Current Sensor basic question

Bill

I certainly agree for what I'd call a common hall effect transformer 

with the sensor in a  gap of a magnetic torus and the wire through the 

center hole but the pic that came up when I clicked on Don's link just 

appeared to be hall sensors strapped directly on both the sides of the 

wire.  I would expect such an arrangement to be affected by wire diameter?

Ken



On 09/07/2016 4:29 PM, Bill Putney wrote:

 	  Quote: 	
		   



 If it's a Hall Effect sensor the wire size doesn't matter. Magnetic 

 field is what the Hall Effect device is measuring. What dictates the 

 magnetic field strength is Ampere-Turns. I assume you have the wire 

 only passing through the sensor once (one turn).



 A smaller wire will have more voltage drop across it for any given 

 current flow than a larger one, but won't change the current measurement.



 Look at your installation. If the wire and the sensor is laying 

 tightly with other wires, the field may be effected. This should be a 

 very localized effect so if you have about 1/2" from other wires 

 carrying current you should be OK.



 Bill Putney - WB6RFW

 Chief Engineer

 KPTZ - Port Townsend, WA



 PP-SEL/A&P-IA



 "...you know me to be a very smart man. Don't you think if I were 

 wrong, I'd know it?" -Sheldon Cooper



 On 7/9/16 12:34 PM, donjohnston wrote:

> 

> <don(at)velocity-xl.com>

>

> I'm using the 50a hall effect sensor which came with my Grand Rapids 

> EIS 6000.  But the current numbers don't jibe with the VPX. It's not 

> a huge difference, but enough that I don't like it.

>   I've talked with GRT and verified the offset and scale factor 

> configuration but it's still not right.

>   While searching to see if anyone else was having this issue I ran 

> across an aftermarket sensor.

>   High accuracy current sensor

> http://www.crazedpilot.com/high-accuracy-current-sensor-for-5v-input-7-30v-supply-engine-monitor-systems-dynon-mgl-grand-rapids-garmin-and-more-ems-efis-systems/ 

> Interestingly, it looks just like the GRT sensor.

>   I contacted them to make sure it would work with the EIS6000 and if 

> it came with the offset and scale factor values that needed to be 

> configured on the EIS. They said yes and that the correct values were 

> based on the wire size being used.  There is nothing in the GRT 

> documentation about the wire size having an effect on the offset and 

> scale factor settings.

>   Is it true that the size of the wire effects the reading of a hall 

> effect sensor?

>   Don

>

>

> Read this topic online here:

>

> http://forums.matronics.com/viewtopic.php?p=457996#457996

>

>

donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Sat Jul 09, 2016 1:11 pm Post subject: Re: Current Sensor basic question

Can you elaborate on the tweaking process?  For example did you adjust the scale factor or offset?  Which direction did you change for what effect?



 	  yellowduckduo(at)gmail.co wrote: 	
		  I can believe that wire size affects that sensor but not the hollow 

round 60 amp sensor that GRT sold me several years ago.

The wonderful thing about the GRT sensor is that you can adjust the 

offset and scale for almost any sensor.  IMO the values from GRT are 

simply a recommended starting value and all of my sensors benefited from 

some tweaking when I calibrated them.

Ken



On 09/07/2016 3:34 PM, donjohnston wrote:

donjohnston

Joined: 13 Dec 2009
Posts: 231

Posted: Sat Jul 09, 2016 1:13 pm Post subject: Re: Current Sensor basic question

Only one pass through the sensor.  No other wires within about 4-6".



 	  billp(at)wwpc.com wrote: 	
		  If it's a Hall Effect sensor the wire size doesn't matter. Magnetic 

field is what the Hall Effect device is measuring. What dictates the 

magnetic field strength is Ampere-Turns. I assume you have the wire only 

passing through the sensor once (one turn).



A smaller wire will have more voltage drop across it for any given 

current flow than a larger one, but won't change the current measurement.



Look at your installation. If the wire and the sensor is laying tightly 

with other wires, the field may be effected. This should be a very 

localized effect so if you have about 1/2" from other wires carrying 

current you should be OK.



On 7/9/16 12:34 PM, donjohnston wrote:

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Jul 09, 2016 3:06 pm Post subject: Current Sensor basic question

 	  Quote: 	
		  

 High accuracy current sensor

  http://www.crazedpilot.com/high-accuracy-current-sensor-for-5v-input-7-30v-supply-engine-monitor-systems-dynon-mgl-grand-rapids-garmin-and-more-ems-efis-systems/  	


   This is obviously not a 'cored' sensor.

   Because there is no control over the

   concentration of flux in the measured

   wire, there is similarly no physical filtering

   of external magnetic fields normally afforded

   by the use of a gapped core.



   Hence, the need for two sensors on opposite

   sides of the wire. Magnetic lines of force

   will be equal/opposite in the two sensors

   where the sum of the two will represent

   a field proportional to flux surrounding

   the wire. 



   Flux from outside the sensor pair will

   affect each sensor approximately the same

   and since they're wired for adding opposing

   fields, non-opposing fields tend to cancel

   each other.



   As long as the instrumentation system has adequate

   accommodation of scale factor and offset, then

   this 'coreless' approach seems reasonable.



   I use a closed loop, gapped core sensors in

   my instrumentation packages. One of my favorites

   is this critter



  http://tinyurl.com/zxsdyj4



 



      [img]cid:.0[/img]



  It's core function is a plus-minus 6A sensor

  but easy to 'jeep' into fractional multiples and

  sub multiples of 6A. Of course, it's designed to

  mount on an ECB but I've converted dozens of them

  to remotely installed sensors at the end of pendant

  cables. 



  These are gapped-core, closed-loop sensors with

  great linearity and calibration numbers. They

  too could probably be adapted to the popular 

  displays. The price sure is right.



  



 

   Bob . . .

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yellowduckduo(at)gmail.co
Guest

Posted: Sat Jul 09, 2016 3:27 pm Post subject: Current Sensor basic question

Don

The formula is in Section 7.1.5 "Transfer Function" in my GRT manual.

 From a quick refresher it seems that increasing the Aux Scale Factor 

increases your reading by MULTIPLYING all sensor outputs by a larger 

scale factor. Increases or decreases each reading by a similar 

percentage so to speak.

Changing the offset simply adds (or subtracts) the same value to all 

readings. For example you could change this by some value that adds say 

5 amps to all indications. It would then add 5 amps to the indication 

even when no current is flowing, and 5 amps to all readings.  Tweak this 

by an even number such as -2 or +2. Changing it by an odd number such as 

1 or 3 reverses the direction for example from adding to subtracting.

If you describe what you are seeing on the display and what it actually 

should be at one point preferably somewhere near a normal cruising 

current and also with zero current flowing (such as with no wire or a 

disconnected wire in the sensor) we can make a suggestion as to what 

tweaking might help. There is an interaction in that we get the 

multiplier correct and then use the offset to make it read zero when no 

current is flowing. Sometimes it takes a couple of tries.

The suggested values from GRT for my sensor were Aux Scale Factor = 93 

and Aux Offset = 177 so you probably have those set as a starting point 

if it is the same sensor and you are setting it for +/- 50 amps.

Increasing the Aux Scale Factor to 94 would slightly raise all displayed 

readings especially the highest readings.  If it then reads above zero 

with no current flowing you'd try tweaking the Aux Offset to maybe 175 

to lower the zero current display a bit.

Ken

On 09/07/2016 5:11 PM, donjohnston wrote:

 	  Quote: 	

 Can you elaborate on the tweaking process?  For example did you adjust the scale factor or offset?  Which direction did you change for what effect?

 yellowduckduo(at)gmail.co wrote:

> I can believe that wire size affects that sensor but not the hollow

> round 60 amp sensor that GRT sold me several years ago.

> The wonderful thing about the GRT sensor is that you can adjust the

> offset and scale for almost any sensor.  IMO the values from GRT are

> simply a recommended starting value and all of my sensors benefited from

> some tweaking when I calibrated them.

> Ken

>

> On 09/07/2016 3:34 PM, donjohnston wrote:

>

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=458012#458012

 .

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