How does load cell work?
What is loadcell?
Load Cell is a device that converts force into electrical signal.
Strain gage based load cell is made of a specially engineered mechanical component called as an element. Four strain gauges are positioned precisely and bonded on to the element using a special adhesive. (strain gauge is a device that changes resistance when it is deformed or stressed).
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The force-electrical signal conversion happens in two stages-
- force applied deforms the element which in turn deforms the strain gauges
- How does a strain gauge sensor work?
- strain gauges converts the deformation to electrical signals
The strain gauges are wired in Wheatstone bridge configuration. The bridge is connected to a power supply unit and a signal conditioner through a 4-core cable. When an input voltage (10VDC) is applied to the bridge, the output is a voltage in the range of few millivolts.
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The load cell output is proportional to the load applied to the element.
Wheatstone Bridge
What is sensitivity of load cell?
Basic specifications of a load cell-
- Capacity (kg)
- Full scale Output (mV)
- Sensitivity (mV/V)
- Excitation Voltage (VDC)
- Input resistance (ohms)
- Output resistance (ohms)
What is a load cell calibration?
Below are the commonly used standard values-
- Excitation voltage: 10V or 12V DC
- Full scale output: 10mV, 20mV and 30mV
- Load cell sensitivity: 1mV/V, 2mV/V and 3mV/V
- Input resistance: 350Ω and 700Ω or 1000Ω
- Output resistance: 350Ω and 700Ω or 1000Ω
- Kobastar cable color code:
- Excitation + Red
- Excitation – Black
- Signal + Green
- Signal – White
