Reading load cell outputs, especially when reading datasheets, is key to choosing the right load cell for your application and getting accurate results. Load cells are used to measure weight or force and the output signal is what tells you what those measurements mean. In this article, we’ll explain what the output signals mean, how to calculate them and the key specs you’ll see to make sure it works in your system.
What is Load Cell Output?
Load cell output is the signal the load cell produces when a load is applied. It’s expressed in millivolts per volt (mV/V) and shows the relationship between the load and the excitation voltage to the load cell. This is important so you can have consistency across different load cell models even if the output ranges are different.
The key parameters that define load cell output are:
- Excitation Voltage: The voltage supplied to the load cell to enable it to measure.
- mV/V (Millivolts per Volt): The unit expresses the output signal relative to the excitation voltage applied to the load cell.
- Rated Capacity: The maximum load the load cell can measure.
Accurate load cell output readings are key to your system meeting its performance requirements. Precise reading and understanding of these signals means measurements across applications and reduces the chance of miscalculations or equipment overload.
Why Understanding Load Cell Output Signals Matters
Whether you’re in manufacturing, agriculture or transportation, understanding how these signals work is important for accurate measurements and system maintenance. Knowing the key specs of these signals helps you make informed decisions on calibration, system maintenance and overall performance. These specs are critical to the load cell operating within its design parameters and giving you consistent and reliable results.
Key signal characteristics are:
- Output Sensitivity: Typically 2-3 mV/V
- Zero-Balance Readings: A low zero offset is important for accuracy
- Temperature Compensation: For stability across temperature changes
- Signal Stability: For reliability over time
Load Cell Output Measurements
Load cell output signals can be measured in several ways, and FSO and maximum output are the two most important to understand. These measurements will determine the load cell’s operating range and safe operation. Let’s look at each type of measurement and how they affect your load cell.
Full-Scale Output (FSO)
Full-scale output is the load cell’s signal at its rated capacity. When a load cell is loaded to its maximum capacity, it produces a specific output signal that’s the reference point for all measurements.
Key characteristics of FSO:
- Provides baseline measurement reference
- Rated in mV/V (e.g., 2 mV/V)
- Scales linearly with an excitation voltage
- Used for calibration and setup
For example, a load cell rated at 2 mV/V will output 2 millivolts for every volt of excitation when loaded to its rated capacity.
Maximum Output
Maximum output is the highest output signal the load cell can produce beyond its rated capacity. This measurement prevents overload damage and ensures safe operation.
Key characteristics of Maximum Output:
- The highest safe operating signal
- Includes a safety margin
- Varies with environmental conditions
- Should never be exceeded during operation
For example, a load cell might have a 2 mV/V FSO rating, but its maximum output could be 3 mV/V to give you operational headroom of 150% for temporary situations. It is not recommended that the load cell be operated beyond its rated capacity.
How to Calculate Load Cell Output
Calculating load cell output is important for system setup and troubleshooting. The formula is simple, applied weight divided by rated capacity and full-scale output. This is linear within the load cell’s specifications.
The formula is:
Output = (Applied Load ÷ Rated Capacity) × (Full Scale Output × Excitation Voltage)
Example:
Let’s calculate the output for a 500 kg load cell.
- Applied Load: 250 kg
- Full-scale output: 2 mV/V
- Excitation Voltage: 5V
Here’s the step-by-step:
- First, divide the applied load by the rated capacity: 250 kg ÷ 500 kg = 0.5
- Then multiply by the full-scale output and by the excitation voltage: 0.5 × (2 mV/V × 5V) = 5 mV
In short, when you put 250 kg (half the rated capacity) on your load cell it will output 5 mV, which is half of what it would output at full capacity.
This is important because it allows you to know if your load cell is working correctly. If the output doesn’t match the expected value it could be a calibration, wiring or signal interference issue. This also helps you troubleshoot and verify your system is set up for accurate weight measurements.
Key Applications That Use Load Cell Output Data
Load cell output data is used across many industries for real-time accurate measurements to drive efficiency, safety and quality. By converting weight or load measurements into electronic signals, load cells provide data to monitor, control and optimize critical processes. Here are some of the key applications where load cell output data is used:
- Manufacturing and Production Lines: Load cell data helps manufacturers monitor material weight during production to ensure consistency, meet quality standards, and reduce waste.
- Agriculture and Farming Operations: In agriculture, load cell data tracks feed levels and equipment loads so farmers can optimize feed distribution, improve livestock health, and reduce operational costs.
- Construction and Heavy Lifting: Load cell data is used to monitor the weight of loads lifted by cranes and hoists to ensure safe lifting operations and prevent overloading that could damage equipment or cause accidents.
- Transportation and Logistics: Load cells provide data on vehicle weight and load distribution so logistics companies can ensure weight compliance, optimize fuel efficiency and reduce wear on vehicles.
- Aerospace and Defense: In aerospace, load cell data is used to test the structural integrity of components such as landing gear to ensure they meet safety standards and perform under various load conditions.
- Oil and Gas Industry: Load cell data tracks loads on rigs and pipelines to prevent equipment failure, reduce maintenance costs, and ensure safety in harsh environments.
- Energy Sector (Wind Turbines and Solar Panels): Load cell data monitors the stress on renewable energy installations such as wind turbines and solar panels so operators can predict maintenance and extend equipment life.
Factors Affecting Load Cell Output
Load cell accuracy depends on maintenance and operating conditions. Calibration ensures reliable measurements, and installation prevents mechanical issues that can affect the readings. Temperature and environmental changes can affect accuracy, so compensation is critical.
Critical maintenance items:
- Zero-balance checks
- Temperature monitoring
- Connection verification
- Calibration documentation
Troubleshooting Load Cell Readings
When you have issues with load cell readings, systematic troubleshooting helps you find the root cause. Signal instability means electrical interference or connection problems. Zero drift means temperature changes or mechanical issues.
Common troubleshooting steps:
- Verify power supply stability
- Check cable connections
- Inspect for physical damage
- Test zero-balance output
- Test signal output under load
- Measure resistance between wires of disconnected load cell: Red-Black, White-Green, Red-Green, Red-White, Black-Green, Black-White.
- Compare the results with the load cell specification.
Load Cell Operation Best Practices
Load cell operation requires attention to both technical and practical considerations. Start with proper installation and regular maintenance schedules. Document all calibrations and keep system performance logs. This history will be invaluable when troubleshooting or planning maintenance.
Operational guidelines:
- Stay within rated capacity
- Monitor environmental conditions
- Keep maintenance records
- Schedule inspections
- Schedule regular re-calibrations
Get Professional Help
Some issues require expert help, like complex calibrations, reading variations or physical damage. Get to know qualified technicians or your supplier for support.
Signs you need help:
- Accuracy issues
- Calibration failed
- Physical damage
- Electrical problems
Get in Touch with Our Experts at Massload Today
Understanding load cell outputs makes your system better and more reliable. By calibrating properly, following maintenance schedules and addressing issues promptly, you will get accurate measurements and longer equipment life. Remember that proper documentation and regular monitoring form the foundation of a successful load cell operation.
For more insights into load cell technologies and solutions, explore our blog content or get in touch with one of our experts.
