Load cell - Wikipedia, the free encyclopedia
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A load cell is a transducer that is used to convert a force into electrical signal. This 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.
Do You have some number on it?
This seems to me a bit different thing as compared to the Weighing relation.They are usually connected with a shaft (roller) that rotates and take the packaging film to the rewinding shaft.
Hi phat,
Can you upload an image of this ?
Here is heavy info package...............
Load cells
Load Cell - Load Cells | Load Cell Accessories | Load Cell Displays | Load Cell Instruments
Troubleshooting Guide
**broken link removed**
Applications | Load Cell
Load Cell Application | Load Cell Applications
You wrote about shaft , there is Rotary Torque Sensor Models too.......
Torque Sensor | Torque Sensors
Applications | Torque Sensor
Torque sensor application | Torque sensor applications
How load or force cell work
how sensors work - load cells
Introduction to Load Cells
Load Cell
LOAD CELL TECHNOLOGY IN PRACTICE
https://www.aeroconsystems.com/electronics/load_cell_primer.pdf
can we test it ? If yes then how ?
Yes we can,
but how...... it depends the type of device and connector wiring.
First we need to know manufacturer and exact type and model codes and numbers,
then we must try to find all data and wirings for device.
How to test LVDT ?
Can LVDT be used as a strain gauge ?
HI phatcreator,
Can you give me the Brand name and the model number of the machine in which these are used?
Look live principle first here........
How it Works - LVDT
As you findout for testing you need,
supply ac-signal to primary and
check secondary output with scope.
Supply voltage and frequency can vary between different LVDT types.
Usually (50....15000Hz )
For test supply you can use for example 5Vac 50Hz with 100 ohm 1/4W series resistor ,
connected for protect primary against overcurrent.
Allways 1. thing to do before testing , find out electrical data and connections.
Coils can simply check with ohm-meter. ( only for check , are coils fully damaged )
Some LVDT types have secondary midpoint output connection too. ( 3 secondary pins )
Test connection...............
View attachment 63440
No.
But LVDT can be used indirect for force measurement with different mechanical solutions
by converting the tension or force into a linear or angular movement.
Linear Variable Differential Transformer (LVDT)
is a type of electrical transformer used for measuring linear (i.e. translational) displacement.
Metrolog - LVDT Transducers
Same principle are used in rotary variable differential transformer (RVDT)
It is a type of electrical transformer used for measuring angular displacement.
Metrolog - RVDT Transducers
as you mentioned in your text that, " Some LVDT types have secondary midpoint output connection too. ( 3 secondary pins ) " .... So, the testing circuit that you provided is enough to test this type of LVDT in the same as a normal LDVT ??
look allways first at datasheet.........What should be the coils ohmic values for a given LVDT ? Can you take any example of it ?
there are different images of different types of LVDTs , but how to apply the testing circuit procedure to any of these ?
which one is the primary ? which one is the secondary ? which one should be taken as output ? which one taken as ground ?
goto Metrolog - LVDT Transducers (AC output)
and select for ex. PCA-116 Series
you find LVDT Schaevitz® Transducers - PCA-116 Series
open PDF for datasheet
you find this page https://www.metrolog.net/files/tech...splacement/gagehead/pca_116_enus_metrolog.pdf
There you find all data needed for normal use.
-specifications
-dimensions
-wiring
look allways first at datasheet.........
for ex. PCA-116-100
Primary 660 ohm , secondary 960 ohm
again look allways first at datasheet.........
-this type of LVDT dont care which wire is GND, only transformer phase shifts 180 degrees.
for ex. PCA-116-100 test circuit............
View attachment 63477
But remember there is lots of different versions of basic principle of LVDT
look dataseets again..........
- AC output as above
- DC output
- current loop output
- RS-485 output
- USB output
- etc, etc.....
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