Load cells are a staple in the industrial weighing world, converting applied force into a signal. But what’s the role of voltage in these devices?
Let’s dive in and learn about load cell voltage and why excitation voltage is crucial for accurate and reliable measurements.
Load Cell Basics
A load cell is a type of force sensor that converts mechanical force into an electrical signal. In industrial settings, they’re a must-have for process control, quality assurance and more. Here’s a quick rundown of the types of load cells you’ll encounter:
- Strain Gauge Load Cells: Most common in industrial applications. Accurate, versatile and cost effective.
- Hydraulic Load Cells: Uses fluid pressure changes to measure force. Robust but less common in modern digital systems.
- Pneumatic Load Cells: Uses air pressure, for environments where explosive hazards exist.
Of these, strain gauge load cells are the most popular as they are highly precise and reliable. You’ll find them on hoppers, tanks and reactors to prevent overloading of these vessels.
Load Cell Specifications to Consider
When choosing a load cell, you’ll come across several specifications that affect its performance.
Here’s what they mean:
- Capacity: This is the maximum weight or force the load cell can measure. Overloading beyond this will damage the load cell or give inaccurate readings.
- Measurement Range: This is the range within which the load cell will give accurate measurements. Make sure to match this range to your application.
- Accuracy: Crucial for precise measurements. Includes linearity, hysteresis and repeatability.
- Sensitivity: This is the smallest force a load cell can measure reliably. It’s usually expressed in millivolts per volt (mV/V).
What is Excitation Voltage for a Load Cell?
Let’s get into one of the specifications: excitation voltage. If you’ve ever wondered, “What is excitation voltage for a load cell?” Here’s the simple answer: Excitation Voltage is the electrical voltage supplied to a load cell, usually 5V to 10V. It’s what powers the wheatstone bridge circuit comprising strain gauges inside the load cell to measure force.
How Excitation Voltage Impacts Load Cell Sensitivity
Load cell voltage excitation is directly related to sensitivity when measuring force:
- Higher excitation voltage means a more sensitive load cell that can detect smaller changes in force.
- It also enhances the signal-to-noise ratio and reduces the effect of electrical noise on the output signal.
Here’s a quick comparison:
| Excitation Voltage | Sensitivity | Signal-to-Noise Ratio | Common Usage |
| 5V | Moderate | Lower | Budget applications, low-noise environments |
| 10V | High | Higher | Precision applications, industrial use |
While most load cells work at 10V, they can also work at 5V, so they’re versatile for many applications. But lower excitation voltage makes the load cell more prone to electrical noise which can affect accuracy.
Output Load Cell Excitation Voltage and Signal Conditioning
The output voltage of a load cell is proportional to the force applied. In other words, more force means higher output voltage. But this output is very low, usually in the millivolts range, which is where signal conditioning comes in:
- Signal Conditioners amplify and filter the output signal so it can be read by devices like digital displays, PLCs or data acquisition systems.
- By improving the signal-to-noise ratio, signal conditioners ensure the measurements are accurate even in noisy industrial environments.
Pro Tip: If you’re getting erratic readings, it might be due to poor signal conditioning or interference. A good quality signal conditioner can help stabilize the output.
Load Cell Installation and Maintenance Best Practices
Proper installation and regular maintenance is key to extending the life of your load cell and accuracy:
- Install Correctly: Load cells should be installed to minimize stress and prevent mechanical interference. Incorrect installation can cause inaccurate readings or damage.
- Calibrate Regularly: Over time, environmental factors can affect the load cell’s performance. Regular calibration ensures your measurements are accurate.
- Check for Interference: Electrical noise from nearby equipment can interfere with the load cell’s signal. Shielded cables and proper grounding can help mitigate these issues.
The Relationship Between Calibration and Excitation Voltage in Load Cells
Calibration and excitation voltage both relate to load cell performance and understanding this relationship is necessary to get accurate readings. Here’s why:
1. Output Signal Dependence
The output signal of a load cell is directly proportional to the excitation voltage supplied. So, if the excitation voltage changes, the output signal also changes, even if the applied force is constant.
- Example: If a load cell is calibrated with 10V excitation and produces 20mV output at a certain load, reducing the excitation to 5V will give 10mV output. This can give wrong weight readings if the calibration isn’t adjusted accordingly. This is usually taken care of within the load cell indicator.
2. Calibration Accuracy
During calibration, the load cell’s output is measured against known weights or forces with a fixed excitation voltage. This process creates a relationship between the applied load and the output signal, often expressed in mV/V (millivolts per volt). Any deviation from the calibrated excitation voltage during regular use will introduce errors.
- Consistency is Key: If the load cell is calibrated with 10V excitation, it should be operated at the same voltage to get accurate weight readings.
3. Sensitivity and mV/V Rating
The sensitivity of a load cell, specified in mV/V, is how much the output signal changes per unit of excitation voltage for a given load. Calibration relies on this sensitivity value.
- Example: A load cell with 2mV/V sensitivity will give 20mV output at 10V excitation when a certain force is applied. If the excitation voltage is reduced to 5V the output signal will be 10mV for the same force. This is why changing the excitation voltage after calibration will give wrong readings.
4. Effect on Linearity and Stability
A stable excitation voltage ensures the load cell’s output is linear and predictable which is crucial for calibration. Fluctuations in excitation voltage can cause:
Non-linearity
The relationship between the applied force and the output signal becomes inconsistent and affects calibration accuracy.
Signal Drift
Changes in excitation voltage can cause output signal drift and make it difficult to get accurate readings over time.
Explore More Tips for Precision and Reliability in Load Cell Technology
Understanding load cell voltage is important for getting accurate readings in any industrial environment.
Whether it’s the impact of excitation voltage on sensitivity or the importance of proper signal conditioning, paying attention to these details can make all the difference. Accuracy, reliability and the efficiency of your operations start here.
Curious to learn more? Dive into our other blog posts to explore the ins and outs of load cell technology and how it can enhance your industrial applications.
