Load cell sensor (Single Point Load cell)

Single Point Load cell

A load cell is a sensor or a transducer that converts a load or force acting on it into an electrical signal.  This electrical signal can be a voltage change, current change or frequency change depending on the type of load cell and circuitry used. The most common use of this sensor is in weighing machine. Load cells are used in several types of measuring instruments such as weighing scales, universal testing machines. Every weighing machine which shows weight has a load cell as a sensing element. 

The conversion is indirect and happens in two stages. Through a mechanical arrangement, the force being sensed deforms a strain gauge. The strain gauge measures the deformation (strain) as an electrical signal, because the strain changes the effective electrical resistance of the wire. A load cell usually consists of four strain gauges in a Wheatstone bridge configuration. Load cells of one strain gauge (quarter bridge) or two strain gauges (half bridge) are also available.

The electrical signal output is typically in the order of a few millivolts and requires amplification by an instrumentation amplifier before it can be used. The output of the transducer is plugged into an algorithm to calculate the force applied to the transducer.

  

Commonly available load cells include:

§  S-Beam Load Cell

§  Single Point Load Cells

§  Shear Beam Load Cells

§  Pancake Load Cells

§  Button Load Cells

§  Through hole Load cells and

§  Miniature and Sub-Miniature load cells

Wiring Identifier:

The wiring of load cell consist of four wires (Plus one cable shielding, optional). The wires are as below. The RED/BLACK are usually given DC excitation voltage. While the GREEN/WHITE are taken as sensing output.

 Specifications:

Parameter	Value
Type	Single Point Load Cell
Total Precision	C3 class
Material	Aluminium Alloy
Surface	Anodized Treatment
Protection	IP65
Suggested Platform Size	350 x 350 mm
Applications	Weighing Scales, Retail, Bench & Counting Scales
Rated Load	40 Kg. Max
Rated Output	2.0mV/V+/- 5%
Zero Balance	+/- 1% Full Scale
Input Resistance	405 +/- 6 Ohm
Output Resistance	350 +/- 3 Ohm
Excitation Voltage	5-12V DC
Nonlinearity	0.017% Full Scale
Hysteresis	0.02% Full Scale
Repeatability	0.01% Full Scale
Creep(30min)	0.015% Full Scale
Operating Temperature	-20 °C to +65 °C
Temperature Effect on Zero	0.017% Full Scale / 10 °C
Temperature Effect on Span	0.014% Full Scale / 10 °C
Insulation Resistance	5000 Mega Ohm(50V DC)
Safe Overload	150% Full Scale
Ultimate Overload	200% Full Scale
Cable	420mm(3mm, 4 wire shielding cable)