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Home > Testing a Load Cell Sensor

Testing a Load Cell Sensor

TESTING A WEIGHT LOAD CELL SENSOR
     

TESTING A WEIGHT LOAD CELL SENSOR

1. With and tester-Ohmeter, like Fluke, measure the following resistances on the load cell wiring.

A INPUT +EXCITATION to –EXCITATION  
B OUTPUT +SIGNAL   to   -SIGNAL  
C   +EXCITATION to + SIGNAL  
D   +EXCITATION to  -SIGNAL  
E   -EXCITATION to + SIGNAL  
F   -EXCITATION to - SIGNAL  
 
The input and output resistance should match the manufacturer’s specifications.
The other resistance readings should all be the same and approximately 75% of the input or output resistance.


2.
With and tester-Ohmeter, like Fluke, measure the following resistances on the load cell wiring.

  A.
All leads to case
  B. All leads to shield.


The resistance should be greater than 5000 mg Ohms. If it is less, there is a chance for signal loss due to leakage to ground. Low resistance usually indicates water in the cable.


3.
Using a digital test meter like Acrotech DTR304A, or similar, measure the following load conditions:

  A. Unloaded
  B. Two or three test loads; unloaded reading should be with manufactures specs; usually 1% of output.

 

 

2 mV/V load cells have 500 counts full scale on the load cell Test meter.
3 mV/V load cells have 750 counts full scale on the load cell Test meter.


4.
If the Acrotech test meter goes into over-range, them use a voltmeter and measure the following voltages:

 

A.
B.
C.

D.

-EXCITATION   to  +EXCITATION (volts)
-EXCITATION   to   + SIGNAL (volts)
-EXCITATION    to   –SIGNAL (volts)
+SIGNAL           to    -SIGNAL (milivolts).
     
.
The D reading should be equal to “B”“C”

Calculate percent of output voltage with the following:
   

Actual zero output       =      D x 100          =     % output
Full scale output                 A x mV/V

 
Scale market and balances Large warehouse inventory of load cells: From laboratory balances up to truck and hopper electronic digital scales.
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