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> News & Information > 20171201 Information Sharing: - Some Hints about Load Cell Output Impedance

20171201 Information Sharing: - Some Hints about Load Cell Output Impedance

2018-01-15


The most common load cell output impedance values of load cells are 350 ohm and 700 ohm (mostly load cells for weight bridge).

 

Actual Load Cell Output Impedance

But when more than one load cell is used, the actual load cell impedance (from the point of indicator) decreases. For examples: -

  • Actual load cell output impedance of a floor platform with 4 x 350 ohm load cell is = 87.50 ohm (350 ohm / 4).
  • Actual load cell output impedance of a weight bridge with 6 x 700 ohm load cell is = 116.67 ohm (700 ohm / 6).

 

On the Indicator Side

Both minimum and maximum load cell impedance values are mentioned on OIML approval document. Let’s use our AFM18 OIML approval as example: -

  • minimum load cell impedance is = 87 ohm
  • maximum load cell impedance is = 1212 ohm 

 

If the actual load cell impedance value of a load cell platform exceeds the limits stated on the approval document, then the whole configuration is not conformed with the approval requirements.

 

Since minimum load cell impedance value determines also the maximum number of load cells which can be driven by the indicator legally. So, engineers are reminded to make sure that the actual load cell impedance of a load cell platform falls within approved limits of the indicator.

 

Fidelity Measurement always allow at least 50% safety margin to the maximum load cell numbers listed on our indicator product catalogues. This safety margin is important for system reliability and stability.

 

We hope that the above is useful for you. Should you have any questions about the above, please feel free to contact us.

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