Looking for low-cost load cell with intergrated 4-20mA amplifier

[OkiePC]

http://www.stellartech.com/sensors/2013/01/rod-end-shackle-tension-load-cell-series-rde900/

 

[SHolt]

Don't know the prices but try these:

http://www.megatron.de/en/category/load-cells.html

 

[Miel]

Brosa has that kind of loadcells,

http://www.brosa.net/en/products/tension-load-cell.html

Grtz, miel

 

[JesperMP]

Futek has an inline amplifier. This comes close to what you're looking for.
https://www.futek.com/csg/overview.aspx

No. I cant install that one in the field without a terminal box. I want to eliminate the extra terminal box.

More info. This one has integrated amp, 4-20 mA:
http://www.futek.com/product.aspx?stock=QSH01663

Comes close to my requirements. Only the mounting is a bit odd. It seems you have to bolt the loadcell to the load by the outer ring of holes, and then suspend it by the middle threaded hole.

http://www.stellartech.com/sensors/2...series-rde900

Looks like they can fit my requirements.

Don't know the prices but try these:
http://www.megatron.de/en/category/load-cells.html

This one looks like it fits my requirements:
http://www.megatron.de/en/products/s-beam-load-cells/s-beam-series-kt1101.html

Don't know the prices but try these:
http://www.megatron.de/en/category/load-cells.html

Looks good but expensive.

The one suggested by SHolt is the closest to the one I have imagined.
I wrote initially that there has to be eyelets. It is not so important if there are integrated eyelets, or a threaded pin, or a threaded hole. It is only important that tension can be applied.
edit: I think the proper designation is "inline" loadcell.

Thanks to all so far

 

[Lemming]

Are the built in amplified loadcells more economical than a standard loadcell and a box in the middle ??

If you just want to simplify the circuit maybe native LC inputs on your preferred platform is another option ??

 

[JesperMP]

Are the built in amplified loadcells more economical than a standard loadcell and a box in the middle ??

I am certain that the loadcell with integrated converter that I have seen (but dangblasted cant remember where) was branded "economical".
A box is surprisingly expensive if you factor in also the necessary fixture, installation, split cables.
In my case, I can gather several analog inputs in the area in a box where you cannot install a loadcell converter.

If you just want to simplify the circuit maybe native LC inputs on your preferred platform is another option ??

I use Siemens, and dedicated loadcell inputs (Siwarex) are frustratingly expensive. And, I also dislike having to pull special loadcell cables all the way.

I am thinking that the requirement for a loadcell converter and special calibration procedures, special cables etc. etc. may be a thing of the past. Why cant a loadcell just be like any other analog transducer ?

In my case, I do NOT have to regularly calibrate and certify the loadcell. It is just a simple measurement used by my process.

 

[Lemming]

Have used the Beckhoff KL3351 terminals previously for load cells, and found them affordable relative other methods at the time.. Just need 3pr's cable out/ LC. If you have a pile of LC's local, could throw a coupler & modules in a box adjacent.??

 

[JesperMP]

I cannot switch PLC hardware just because of the load cells.

 

[kamenges]

Originally posted by JesperMP:

I am thinking that the requirement for a loadcell converter and special calibration procedures, special cables etc. etc. may be a thing of the past. Why cant a loadcell just be like any other analog transducer ?

Loadcells are typically used in pairs or quads and the user is generally concerns about the total force measured, not the individual cell weights. In addition the weight value often needs to be quite accurate. "Accurate" tends to mean complex, stable (read "expensive") electronics. In a situation like that it is more economical to have one set of electronics than to duplicate that for each loadcell. In addition, zeroing and calibrating one interface point is more within the reach of the average user than doing the same thing with multiple interfaces.

Granted, in a case where you have a single loadcell or multiple loadcells with the desire to have independent force information, then an integrated amplifier makes much more sense. But I think that is the industry exception, not the rule. And we all know that manufacturers tend to design around the rule, not the exception.

Keith

 

[JesperMP]

Loadcells are typically used in pairs or quads and the user is generally concerns about the total force measured, not the individual cell weights

True, except for commisioning and troubleshooting. When commisioning and troubleshooting, being able to see the value from each sensor is a god-send.
Individual channels also mean that the control system can automatically detect "suspicious" conditions and alert the operator.
We actually have simple inexpensive load-cell converters with electrically summed signals, as well as more expensive load-cell converters that monitors and displays all signals as individual channels.

In this particular case I just need 1 signal, but even if I needed more it would be simpler and better with 1 signal per PLC channel. And PLC inputs are inexpensive.

In addition the weight value often needs to be quite accurate.

Not more accurate than any other sensor.

"Accurate" tends to mean complex, stable (read "expensive") electronics.

Where is the argument that sensor and electronics should not be mated together, expensive or not ?

 

[kamenges]

Originally posted by JesperMP:

When commisioning and troubleshooting, being able to see the value from each sensor is a god-send.

I can honestly say that my trusty Fluke and I have never been hung up by a loadcell for more than 15 minutes. While my time may be valuable, it isn't gold.

Originally posted by JesperMP:

And PLC inputs are inexpensive.

Then go with the thermocouple input module. That is the most direct method and gets rid of a whole bunch of electronics.

Originally posted by JesperMP:

Where is the argument that sensor and electronics should not be mated together, expensive or not ?

From your first post:

Originally posted by JesperMP:

I am looking for an inexpensive load-cell with integrated 4-20mA amplifier.
emphasis added

You put the restriction there yourself.

Given an unlimited budget we would all do things differently than we do. One of the functions of engineering is to make value decisions about technology. It's referred to as cost-benefit analysis.

Keith

 

[JesperMP]

From your first post:
You put the restriction there yourself.

I dont agree with that. Combining the loadcell and converter together in one unit will be less expensive than splitting them into separate units, everything else being equal.

 

[Lemming]

Try these dudes.. http://www.eilersen.com/

Have analogue and comms options, though not sure it will fit your "economical" requirement...

Edit, had another look, and box is still involved...

 

[OkiePC]

I upgraded a Metler Toledo inline "checkmate" case check weighing scale with a compactlogix brick and a module from Hardy Instruments that made setting the four corner system up and calibration a breeze, no multi-meter required, all from the HMI. All the hard work is done for you. I used their "IT" summing board which includes a pair of extra wires for serial commands to read calibration values from their IT load cells as well as allowing you to select any of the connected load cells individually for testing and setup. They make modules for most popular PLCs, and I highly recommend them. That scale was so much more user friendly with a little G306 and the Hardy "IT Technician" tools built into the module not to mention all common scale functions that you simply call to set up tare, auto-tare, noise reduction (which was my concern on a little conveyor), and more.

 

[JesperMP]

Try these dudes.. http://www.eilersen.com/
Have analogue and comms options, though not sure it will fit your "economical" requirement...

We already use them !
These are the expensive loadcells we use for the more demanding applications. They are actually digital.