How to check if Load cell is faulty.

I have a load cell to measure the force of the puller. What is the easiest way to tell if load cell is working properly. Also, How do i check if there is a problem with the amplifier.

Apply a known force to it and see if it outputs the correct signal?

how do i check with applying force?

r u using load cell with plc?

Yes the output of load cell is connected to amplifier and from amplifier to PLC

Look at this and see if it answers your question. Ours go into a summing box, then to a scale controller.

George

Sorry:
http://www.eaetech.com/Downloads/LoadCell%20TroubleShooting.pdf

I would say you need to use a dynamometer or digital force gage to apply force (tension or compression) to the load cell in question and compare readings. I would also suggest that you test the entire range of the load cell to include 20, 40, 60, 80, and 100% of the full range. The load cell can be damaged where it may no longer be linear at certain portions of its range. Not knowing your setup its difficult to say, but if the load cell was not forced beyond its limits, I would start by ensuring that there are no mechanical stresses or forces ( linear bearings binding, load cell axis out of alignment with its load etc) affecting the actual readings you are seeing.

If you have similar laod cell spare, disconnect the load cell electrically and mechanically as well and compare the resistance of all the terminals with new loadcell. In our plant We do confirm this way and most of the time we have succeeded.
Good Luck

thanks uSSa .

bornwild said:

I have a load cell to measure the force of the puller. What is the easiest way to tell if load cell is working properly. Also, How do i check if there is a problem with the amplifier.

Click to expand...

Ahh, days of my youth.

you will need some info on the load cell and a multimeter capable of measuring millivolts.

First use the multimeter to confirm excitation voltage to the load cell on the +Exc and -Exc wires at the summation box or at the amplifier.

Colour codes for load cells vary, but common is +Exc(Red) -Exc(Black) +Sig(Green) -Sig(White).

Ensure the +Sense is connected to the +Exc and -Sense connected to the -Exc , if these wires are required.

Note the voltage, example 10Vdc or 12Vdc.

Next, wil no load on the load cell, use the millivolt setting to measure the signal from the load cell on the +Sig, -Sig wires.

Typically load cells have a millivolt/volt rating , usually 2mv/V or 3 mv/V. This means if a 1000lb load cell is applied with 10V volts excitation, at 1000lb of load a full load signal of 20mv , for a 2mv/V rating, or 30mV full load signal for a 3mv/V rating.

With no load , the +Sig -Sig should be close to 1 or 2 mv signal.

Place a known load on the load cell, and the resulting signal should be a percentage of the full load signal based on (Known Weight/Full load weight) * (Excitation voltage * mv/V rating)

thank curly for a detail answer.God Bless

You need a weighing indicator, some standard weighs( depend on your load cells capacity, 20% of norminal load is enough to check the load cells is working properly or not. The weighing indicator manual will have detail how to test.

If the load cells is OK, then use a multimeter to check the amplifier is OK or not, test the 4-20mA or 0-10v, 0-5v... output displayed on the multimeter.