Think of load cell testing as a routine checkup for your equipment. It’s quick and easy, but it can help you avoid bigger problems down the road.
Equalization is all about balance. In a system with multiple load cells, you want to make sure that each one is sharing the load evenly. If one load cell ends up doing more work than the others, your measurements could get messed up. Keeping everything balanced helps you maintain accurate readings, optimize performance and keep your system running smoothly.
With regular testing and equalization you’ll get reliable results and minimize downtime, so you can run more efficiently and safely.
How Do I Test a Load Cell?
Testing a load cell might sound scary but it’s really not that hard. Here’s a simple step by step guide to check if a load cell is good:
Step 1: Visual Check
Start with a quick visual inspection. Look for any obvious signs of damage like cracks in the load cell body, frayed or pinched cables or corrosion around the seals. If it doesn’t look right it probably isn’t.
Step 2: Measure Bridge Resistance
First, disconnect the load cell from the junction box so it is isolated.
Next grab a multimeter and measure the resistance between the excitation wires (usually red and black). The reading should match the specs in the load cell datasheet, usually 350 or 700 ohms.
Now measure the signal wires (white and green). The resistance should also match the datasheet numbers. If the measurement accuracy is off that’s a sign something’s wrong.
Step 3: Measure mV Output at a Known Load
Place a known weight on the load cell and see how it responds. The output signal should change steadily and proportionally, usually measured in millivolts using a multimeter. If the signal is erratic or doesn’t match expectations you’ve got a problem.
It only takes a few minutes to test a load cell but following these steps and catching a problem early can save you a lot of time and headaches later on.
Can I Repair a Load Cell?
Yes in some cases load cells can be repaired but it depends on what’s wrong.
Repairs are possible for:
- External damage to the load cell cable. Remove the damaged part of the cable and use a sealed junction box to join the two cables together.
- Sometimes a damaged cable connector can be replaced too, as long as the internal wires connected to the connector are not damaged.
Repairs are less feasible for:
- Internal failures like internal circuitry problems, such as strain gauge damage, load cell body deformation or load cell body corrosion.
- These are harder to fix by yourself and must be sent back to the manufacturer. Repairing it would cost more but less than purchasing a new load cell.
Repair Checklist:
- Replaceable: Cables and connectors.
- Manufacturer repair: Internal component failures.
- Quick turnaround: Replace the load cell.
Not sure whether to repair or replace? Reach out to an engineer or support team for advice. They can guide you in the right direction.
What is Equalization in Load Cell Testing?
Equalization is all about making sure each load cell is measuring the load evenly. This is especially important when you have multiple load cells in a system like truck scales or hopper setups.
Without equalization the readings can become inconsistent. One load cell might take on more weight than the others and throw off your entire measurement system. Balancing everything out helps you get accurate readings and keep your system running smoothly.
Equalizing Load Cells in Multi-Cell Systems
When you have multiple load cells in your system equalization is what keeps everything working together as it should. If one load cell is underperforming or taking on too much weight the data can get skewed.
Tools You’ll Need:
Junction box with trimming pots
Multimeter (for mV output checking)
Known test weight
A little patience
Step-by-Step: Manual Load Cell Equalization
Zero the System: Start by ensuring there is no load on the platform. Your indicator should read zero. If it doesn’t you’ll need to do a zero calibration.
Place a Test Weight on Each Load Cell: Apply the same known weight to each load cell, one at a time. Try to place the weight directly above the center of each load cell. Record the readings from the indicator each time.
Compare the Readings: Do the readings match? In most cases they won’t. That’s where equalization comes in.
Trim the Pots: Open the junction box and find the trim pot for the load cell that’s reading the highest. Turn it down gradually to lower the output. You’re not boosting the low ones, you’re just reducing the high ones to make everything align. Think of it like adjusting the tallest person in a group photo to make the lineup look more balanced.
Corner Test: Test the system by placing the known weight on each corner again. If the readings are now close, you’ve equalized the system!
Digital Equalization
If you have a digital indicator or smart transmitter you can equalize electronically. This eliminates some of the manual adjustments but the goal is the same: make sure the load is evenly distributed among all load cells.
How to Avoid Unequal Load Distribution in Multi-Cell Systems
To keep things balanced and accurate follow these best practices:
- Use Matching Load Cells: Always use load cells with the same capacity, output sensitivity and model. Mixing different types can mess with your readings.
- Level Surface: An uneven platform leads to uneven weight distribution. Before installing load cells make sure the surface is flat and stable. Even small slopes or flexing can throw everything off.
- Mount the Load Cells Correctly: Load cells need to be installed in the right direction. Installing them backwards or at an angle can cause inaccurate readings. Double check the mounting direction, cable orientation and where the force is applied.
- Use the Right Mounting Hardware: Self-aligning or articulated mounts help absorb shock and correct for minor misalignments. They also reduce side loads which can improve the accuracy of your measurements.
- Don’t Forget to Equalize: Always equalize during installation and re-check during maintenance. It’s the best way to keep your system balanced and accurate.
- Corner Load Test: Do a final test by placing the same known weight on each load cell position. If all the readings are the same you’re good to go.
Keep Your System Running Smoothly with Load Cell Care
Load cells don’t ask for much but they do need a little attention to keep working their best. Regular testing and equalization goes a long way in maintaining accuracy and avoiding downtime. If you’re weighing crops in a grain cart, tank levels or truck loads the reliability of your load cells is key. Keep your system balanced, check regularly and don’t hesitate to call if things go wrong.
Taking care of your load cells isn’t just about fixing things. It’s about knowing every part of your system will work as expected every day. Keep it balanced, test often and your equipment will reward you.
