10-11-2012, 10:59 AM
Load Cells
Load Cells.ppt (Size: 1.66 MB / Downloads: 295)
What is a Load Cell?
A load cell is a transducer that is used to convert a force into electrical signal.
The most common type is a strain gauge load cell.
Strain Gauge
A Strain Gauge is a device used to measure the strain of an object.
The most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern.
How Does It Work?
The gauge is attached to the object by a suitable adhesive.
As the object is deformed, the foil is deformed, causing its electrical resistance to change.
The resistance change is commonly measured using a Wheatstone bridge.
Wheatstone Bridge
A Wheatstone Bridge is an electrical circuit.
Used in a load cell to measure an overall change in resistance.
Increases sensitivity and reduces the affects of temperature.
Compensation for Error
Hysteresis
Effects reduced by material selection.
Creep
Adhesive and geometry of gauge.
Temperature
Wheatstone bridge, additional temperature sensitive resistors in series with the bridge.