Product category:
Loadcells, Force Sensors and Torque Sensors
News Release from: Novatech Measurements | Subject: High-temperature modulus compensation
Edited by the Engineeringtalk Editorial
Team on 13 March 2002
Modulus compensation keeps loadcells
linear
Novatech has developed a novel approach to high-temperature modulus compensation.
All loadcells have output spans that change with temperature This causes significant measurement errors particularly if the loadcell is required to operate over a wide temperature range
This article was originally published on Engineeringtalk on 3 May 2000 at 8.00am (UK)
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The currently used method for compensating for this error in strain gauged loadcells is to use nickel or Balco foil resistors in series with the sensor excitation connections.
The method is limited in accuracy by the nonlinearity of the resistance change of the foil resistors with temperature.
This nonlinearity increases at temperatures above 100C and foil resistors are not suitable for use at temperatures above 200C.
Novatech's new invention compensates for loadcell output span changes with temperature by using passive temperature-sensitive elements in the bridge circuit.
The temperature coefficient of the temperature sensitive elements is adjusted to be the inverse of the sensor's uncompensated span change with temperature.
Accurate linear compensation can be achieved over a temperature range of -50 to +250C.
This method is inherently more linear than traditional methods that employ nickel or Balco resistors in series with the sensor excitation connections, giving performance specification several times better on span (typically 0.0025% output/C) than most other load cells currently available for high temperature use.
With additional trimming over a range of temperatures of particular interest we would expect to achieve better than 0.001% output/C.
Novatech has an international patent application pending for this novel approach to high-temperature modulus compensation, currently available on 70% of Novatech products.
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