Posts

Exploring New Measurement Products Webinar

The Interface Exploring Capabilities of New Measurement Products Webinar details new products, including sensors, instrumentation, and accessories. Our experts will cover dozens of new additions to the extensive 40,000-plus product catalog of force measurement solutions. Interface engineers highlight product features, capacities, use cases, and technical tips in the fast-paced new technical online seminar.

Wonderful World of Wireless Webinar

Interface Wonderful World of Wireless Webinar explores using wireless sensors, instrumentation, and accessories to cut the cable. Our experts detail wireless load cells, wireless testing equipment, best practices, and tips. Learn about wireless telemetry systems, key considerations, and challenges. Interface engineers highlight industry applications and frequently asked questions in this new technical online seminar.

Interface Load Cells Propel New Torsional Force Measurements for Wind Energy Project

Amongst the wide variety of industries that Interface serves, clean and renewable energy sectors are some of the hottest in pursuit of sensor-based solutions. Between private and public funding, and the overwhelming desire for humans to become more sustainable, new energy technology and investment is multiplying at a rapid pace. 

Interface force measurement solutions are used in all types of energy-related applications for wind, solar, hydro, nuclear, geothermal, and emerging energy sources worldwide. We are recognized as a provider of choice for our reliability and accuracy in designing, engineering, testing, innovating, and manufacturing precision sensor solutions for the energy industry.  In fact, we have designed unique load cells that are embedded into some of the largest test and production equipment for energy production in the world. Read Interface Most Promising Energy Tech Solution Provider

Advance technologies in renewable and sustainable energy sources continues to drive the critical need to monitor, test, and validate concepts, equipment, and tools used in procurement. In the global energy industry, many of the alternative source technologies are inventive, newer, and require unique measurement solutions to take on the challenges found in R&D, testing, and production.  

In addition, alternative energy sources in their infancy can be very cost prohibitive going from exploration to consumption. Therefore, it is important that quality, cost effective testing solutions are provided to help researchers, engineers and manufacturers minimize total costs. Interface force testing solutions help to solve and lessen the burden of these challenges by offering a wide range of test and measurement solutions.

New Interface case study reveals how our load cells were used by the PTB in Germany to calibrate and test the world’s largest machine that measures torsional forces related to wind turbines.

Interface force measurement sensors were requested to help Physikalisch-Technische Bundesanstalt (PTB), the national metrology institute of the Federal Republic of Germany, in the design of an innovative wind energy project. As the second largest metrology institute in the world, the PTB has an acclaimed international reputation in research relating to units and precise measurement. 

PTB is a service provider for science, business, and society, and advises the German federal government on all metrology issues. Organizationally, the PTB is a departmental research facility and senior authority within the portfolio of the Federal Ministry of Economics and Climate Protection. For more than 135 years, PTB’s role has been making important contributions to advancing the energy transition, heat transition and climate protection with quality and speed. 

Interface, working in tandem with our esteemed partner Interfaceforce e. K. in Germany, was asked to provide load cell solutions to use in the design and testing of the world’s first traceable torque measurements of up to 5 MN ∙ m for a wind energy facility. As a first of its kind project, the PTB needed to include high accuracy, quality test equipment to guarantee precise and reliable data. Interface solutions fit the exact requirements.  Read the complete case study here.

Summarizing the engagement, PTB endeavored to construct a system with highly accurate and repeatable results, and one that enable bending moments, axial forces, and dynamic excitations of up to 3 Hz. Thereby, making it possible to realize a metrological characterization of dynamic influences in the (MN ∙ m) torque range, as well as in the MN force range. Working closely with PTB, Interface’s experts in Germany worked with the metrology lab engineers to identify the correct products for this unique calibration system.  

These products are being used to calibrate and test PTB’s torque measurement system, allowing the system to provide accurate and repeatable results over time. The custom load cell products Interface provided PTB for this innovative wind energy system, as detailed in Interface Supports Incredible Wind Energy Innovation, included:

The load cells that were chosen helped PTB to create the system needed for its wind energy facility, which allows multi-component transducers to be calibrated in a traceable and practice-oriented way for force and torque. The system is also now the world’s largest machine starting up at PTB, with which the large torsional forces that occur in wind turbines can be precisely measured for the first time.  Read the article: World’s largest device for measuring torque in wind turbines opens.

As we detailed in Load Cells for Renewable Energy Production and Testing, Interface and our incredible distributor network continues to work with engineers and industry leaders to find viable measurement solutions. Pushing the boundary forward on new and renewable energy is rewarding for our company, especially as we help those achieve energy innovation using sustainable, quality measurement solutions.

ADDITIONAL RESOURCES

Geothermal Well Drilling

Interface and Green Energy Innovation

Interface Solutions for Growing Green Energy

Demands for Quality Energy Measurement Solutions

Interface Supports Renewable Energy Innovation

Interface Supports Incredible Wind Energy Innovation

Load Cell Test Stands 101

Load cell test stands are important devices for manufacturers and testing engineers who need to measure the force or torque applied to an object, test specimen, or product. They are typically made up of a frame, one or more load cells, software, and data acquisition instrumentation.

How do load cell test stands work?

Interface load cells are sensors that convert force into an electrical signal. This signal is then amplified and sent to the test stand’s software, which displays and records the force data. The software can also be used to control the test stand, such as setting the speed and duration of a test.

Test stands are used to hold the test object or device and apply force or torque to it. They should be designed to provide a stable and consistent testing environment. It is typically designed to accommodate a wide range of objects of different sizes and shapes. Often a reconfigurable structure to adapt from test to test.

Test stands may have various components, such as a base or base plate, columns, a crosshead, and load introduction devices. Interface provides high-accuracy load cells, instrumentation and DAQ systems, software and accessories designed for use in various types of test stands.

What are the different types of load cell test stands?

There are two main types of load cell test stands: motorized and manual. Motorized test stands are more advanced and can be used for more demanding testing applications. They typically have features such as programmable speed and force control, as well as data logging capabilities. Manual test stands are less expensive and easier to use, but they are not as versatile as motorized test stands.

A test stand and a load frame are both mechanical structures used in materials testing, but they differ in their functions and designs.

The test stand can be a test bench or structure on a test bed plate. These assemblies are designed to rigidly hold an object while it is being subjected to external forces. These forces could be introduced from all angles and orientations and cover low cycle design limit to long duration fatigue cycle testing.

A load frame, on the other hand, is a machine that is specifically designed to apply and measure axial or torsion forces during material or small component testing.

Most Common Requirements for Load Cell Test Stands

Testing professionals, engineers and metrologists require a load cell test stand to perform accurate and precise measurements. The primary features of a test stand include:

  • High accuracy: The load cell test stand must be able to measure force or torque with a high degree of accuracy. This is important to ensure that the measurements are reliable and repeatable. Confidence in the data must be validated through accuracy of measurement.
  • Versatility: The load cell test stand must be able to be used for a variety of testing applications. Test lab professionals, engineers and metrologists need equipment that can perform a wide range of product and material tests. This also includes interchangeable sensors, depending on the capacity and type of test, such as tension or fatigue.
  • Repeatability: The load cell test stand must be able to repeat measurements with high precision. This is important to verify the accuracy of measurements over time, through continuous use and even high cycle counts.
  • Safety: The load cell test stand must be safe to use, even when testing products under high loads. Measurements are not compromised by safety concerns.
  • Ease of use: The load cell test stand must be easy to use, even for users with limited technical knowledge. This is important for testing professionals to be able to quickly and easily set up and use the test stand.

Load cell test stand requirements can vary based on the type of testing projects and materials. Many test stands are standard; however, complex testing programs often require custom test stands that are designed and calibrated for specific use cases. Interface provide load cells, instrumentation and software designed for use in test stands.

Test Stand Sensor Considerations

  • Ensure sensors are properly sized for capacity, cycle, and extraneous load considerations.
  • Multiple bridges are good feature for redundancy and data validation.
  • Thread adapters and connector protectors must be considered in choosing the sensor for a specific test stand application.
  • Multi-axis data capture often requires robust instrumentation to take full advantage of the data.
  • Invest in versatility and ruggedness to maximize return.

Additional Test Stand Options

  • Programmable speed and force controllers help to regulate the rate at which the load is applied to the product, as well as the maximum force that can be applied during a given test period or cycle.
  • Data logging instrumentation records the force data for each test. This data can then be used to analyze the results of the test and to make sure that the product meets the required specifications.
  • Remote monitoring and controls help with test stand use from a remote location. This can be useful to run tests without being physically present at the test stand.

There are many different types of load cell test stands, so it is important to choose one that is right for your specific needs. When selecting or building a load cell test stand, consider the weight or force that you need to measure, the accuracy and precision, the environment in which the test stand will be used and the equipment budget.  This is a topic we detailed in our Testing Lab Essentials Webinar. Watch this portion of the online technical seminar below.

Load Cell Test Stand Use Cases and Applications

  • Aerospace test stands are used to measure the strength of aircraft structures. Test stands are used to test the performance and durability of aircraft components, such as wings, fuselages, and engines. They are also used to test the structural integrity of aircraft materials, such as composites and metals.
  • Material test stands can be used to exam the strength, stiffness, and toughness of materials.
  • Structural test stands are used for small capacity testing, as well as large amounts of force to measure the structural integrity of buildings, bridges, and other formations.
  • Dynamic test stands are used to measure the performance of products under different environmental conditions, such as shock and vibration testing.
  • Medical manufacturers need to test the performance of medical devices. Test stands are used to test the performance and durability of medical devices, such as pacemakers and defibrillators. They are also used to test the accuracy of medical instruments and in-home medical equipment, as the safety of user is paramount to all other requirements.
  • Automotive labs use test the performance of engines, transmissions, brakes and other components. They are also used to test the durability of automotive materials, such as tires and plastics.
  • Consumer product manufacturers and OEMs must test the durability to ensure customer satisfaction and reliability of the product. Test stands are used in testing toys, appliances, tools, and electronic devices.
  • Industrial automation component makers and OEMs must test the strength of machine parts and materials used in product lines, machine tools, and robots. They are also used to test the safety of industrial equipment, such as forklifts and cranes.

Load cell test stands are an essential tool to accurately measure the forces acting on a test specimen. By using a load cell test stand, testing engineers can ensure that their equipment is operating within its design limits and that it is safe to use. If you have questions about building or upgrading your test stand, be sure to consult with our application engineers.

Demystifying Specifications Webinar

Interface’s technical force measurement webinar Demystifying Specifications details descriptions, terms, values and parameters found in product datasheets for load cells, torque transducers, instrumentation and specialty products. Learn from our experts what specifications need critical review, recommendations based on product categories, and the insider point of view on what is most important in terms of specifications for different use cases and tests.

Understanding GUM and Measurement Uncertainty

Understanding GUM and adherence to good test and measurement practices are essential to minimize uncertainties and ensure reliable measurement results for every application.

In the context of test and measurement, GUM stands for Guide to the Expression of Uncertainty in Measurement. The GUM is a widely recognized and internationally accepted document published by the Joint Committee for Guides in Metrology (JCGM), which provides guidelines for evaluating and expressing uncertainties in measurement results.

GUM establishes general rules for evaluating and expressing uncertainty in measurement that are intended to be applicable to a broad spectrum of measurements. A critical portion of any measurement process, the GUM outlines a thorough framework for uncertainty estimation. GUM defines terms and concepts related to uncertainty, describes methods for uncertainty calculation, and offers guidance for reporting and the documentation of uncertainties in measurement results.

The GUM provides a systematic approach to assess and quantify uncertainties by source, including equipment constraints, environmental conditions, calibration procedures, and human factors. The standards set by GUM emphasizes the need for considering and quantifying all substantial uncertainty components to ensure reliable and traceable measurement results.

By following the principles and guidelines outlined in the GUM, test and measurement professionals, metrologists, and scientists ensure standardized approach to uncertainty evaluation and reporting, facilitating comparability and consistency of measurement results across different laboratories and industries.

The uncertainty requirement varies for different use cases and industry applications. For example, for aerospace, defense, and medical devices there are strict uncertainty requirements compared to commercial scales or measurement tests that do not need precision accuracy.

When estimating uncertainty in load cell calibration, it is important to refer to the Guide to the Expression of Uncertainty in Measurement (GUM). The GUM provides a comprehensive framework with general rules for evaluating and expressing uncertainty in measurement. It serves as a guide applicable to a wide range of measurements, providing valuable guidance on uncertainty assessment in load cell calibration and other measurement processes.

In test labs that utilize load cells and torque transducers, the principles and guidelines GUM should be consistently applied to accurately evaluate and express uncertainties associated with the measurements obtained from these devices.

The application of GUM in test labs using load cells and torque transducers requires a thorough understanding of the measurement process, relevant standards, and calibration procedures. Read Understanding Uncertainty in Load Cell Calibration for more information.

Different considerations to measure uncertainty

  • Determine what parameter is to be measured and the units of measure.
  • Identify the components of the calibration process and the accompanying sources of error.
  • Write an expression for the uncertainty of each source of error.
  • Determine the probability distribution for each source of error.
  • Calculate a standard uncertainty for each source of error for the range or value of interest.
  • Construct an uncertainty budget that lists all the components and their standard uncertainty calculations
  • Combine the standard uncertainty calculations and apply a coverage factor to obtain the final expanded uncertainty.

GUM is used to identify and characterize uncertainty sources that can affect the measurements obtained from load cells and torque transducers. These sources may include calibration uncertainties, environmental conditions, electrical noise, stability of the test setup, and other relevant factors. Each of these sources should be quantified and considered in the uncertainty analysis.

Quantitative estimates of uncertainty component contributions to the overall uncertainty need to be determined. This can involve conducting experiments, performing calibration procedures, analyzing historical data, or utilizing manufacturer specifications to obtain uncertainty values for each component.

Once sources and estimates are complete, next step is to combine the individual uncertainty components using appropriate mathematical methods prescribed by the GUM. These methods include root-sum-of-squares (RSS), statistical analysis, and other relevant techniques. The aim is to obtain an overall estimate of uncertainty that accounts for the combined effects of all relevant sources.

The GUM provides guidelines on expressing uncertainties in measurement results. It emphasizes the use of confidence intervals, expanded uncertainty, and coverage factors. The uncertainty should be reported alongside the measurement values, indicating the level of confidence associated with the measurement. This allows the users of the measurement data to understand the reliability and accuracy of the obtained results.

For additional information about GUM, errors and setting an uncertainty budget, watch our webinar Accurate Report on Calibration. The video is set to start on the topic of Measurement Uncertainty.

It is essential to consider the specific uncertainty requirement of the application to ensure that the chosen force measurement device is appropriately calibrated for the project. This resource is a helpful recap: Specifying Accuracy Requirements When Selecting Load Cells.

In addition, understanding GUM, reducing uncertainty with regular calibration of testing devices and proper maintenance of the equipment go together with GUM.

ADDITIONAL RESOURCES

Gold Standard® Calibration System

Accurate Report on Calibration

Technical Information

Load Cell Test Protocols and Calibrations

Regular Calibration Service Maintains Load Cell Accuracy

 

Shunt Calibration Resistors 101

Shunt calibration is a process of calibrating a measurement instrument using a shunt calibration resistor. The shunt calibration resistor is connected in parallel with the measurement instrument to provide a known resistance value, which is used to calculate the instrument’s accuracy.

In shunt calibration, a known current is passed through the shunt calibration (cal) resistor, which generates a known voltage drop across the resistor. This voltage drop is measured using the measurement instrument being calibrated, and the instrument’s accuracy is calculated based on the known resistance value of the shunt calibration resistor and the measured voltage drop. They create a simulation of load and verify the health of the sensor. Commonly, they are used to scale instruments.

The accuracy of the measurement instrument can be calculated by knowing the shunt resistor’s precision level and applying Ohm’s Law, which states that the current passing through a resistor is proportional to the voltage drop across it and inversely proportional to its resistance value.

Shunt calibration can be used to calibrate force measurement devices, including load cells. Interface provides shunt calibration resistors in our accessories line as “loose” resistors. They are also available with engineered to order requests for designs into cables, connectors and even within the load cell.

Shunt calibration is an important process for ensuring accurate and reliable measurements in various industrial, commercial, and scientific applications. It allows measurement instruments to be calibrated quickly and cost-effectively, and it improves the accuracy and reliability of the measurement data.

What is a shunt calibration resistor?

A shunt calibration resistor is a resistor that is connected in parallel with a measurement instrument to provide a known resistance value. The purpose of the shunt calibration resistor is to calibrate the instrument to accurately measure the current passing through it. Shunt calibration resistors are often used with load cells to improve the accuracy and reliability of their measurements.

How are shunt calibration resistors used with load cells?

Load cells typically generate a small electrical signal in response to applied force or weight. This signal is amplified and processed by a signal conditioning circuit before a data acquisition system or controller uses it. The signal conditioning circuit can utilize an internal shunt calibration resistor on the instrumentation side, or activate a resistor located upstream in the system.

Shunt calibration resistors located either in the sensor, cable, or instrument will be switched into the circuit during the shunt calibration process, shunting and diverting current in the process. This shunting effect unbalances the Wheatstone bridge, simulating loaded output from the sensor. Because the resistance value is known, sensor span output and thus instrument scaling can be accurately verified. This electrical simulated signal negates the need for physical force or torque calibration of the system.

The shunt calibration resistor provides a known resistance value, which is used to verify the health and output of the load cell, ensuring accurate system measurement of the applied force or weight. The resistor diverts a small portion of the load cell’s excitation current. The value of the shunt calibration resistor is carefully selected based on the load cell’s characteristics and the desired measurement accuracy.

Shunt calibration uses the shunt resistor to force a load cell bridge to provide a fake signal output. It allows one to check for sensor health and whether the signal behavior has deviated from an original calibration certification with initial shunt output data.

This forced signal output allows for the attached instrument to be scaled. This could be setting signal conditioner scaling:  When the load cell reaches max calibrated force, is the mV/V input properly scaled for the exact 5V, 10V or 20mA conditioner output? The other setting option is displayed units of measurement on a display: Is the load cell’s calibrated 3.999mV/V output at 100 lbs displaying 100 lbs on the display?

Shunt resistors are sized by resistance value to provide approximately two-thirds or three-quarters full scale output signal. Having this recorded value on the calibration certification the instruments can be scaled as necessary for full scale, and future shunt checks can ensure nothing is changing with the health of the circuit.

Interface Shunt Calibration Resistors – RCAL Resistors

Interface shunt calibration resistors, known as RCAL Resistors, are an accessory product. They are made from the highest components and processes to ensure the specifications for your Interface products perform to meet their published specifications. Available RCAL Models include RS-100-30K, RS-100-40K, RS-100-60K, and RS-100-120K are available.

Interface RCAL Resistors are high precision components and provide an effective, method for checking the calibration of a load cell system in the field or when a means of applying actual forces is unavailable.

  • Designed to work with Interface products.
  • Made with the highest quality components.
  • Created to maintain the specification of the product.
  • Precision wire-wound
  • 5 ppm/°C, 0.01%

U.S. dimensions and capacities are provided for conversion only. Standard product has metric capacities and dimensions. U.S. capacities available upon special request and at an additional cost.

What are the benefits of using shunt calibration resistors?

There are several benefits of using shunt calibration resistors in measurement applications:

  • Calibration: Shunt calibration resistors can be used to scale measurement instruments, ensuring that they provide accurate calibrated unit readings. Shunt calibration can often substitute the need for physical force or torque system calibration
  • Convenience: Shunt calibration can provide a quick and easy system health check either before or immediately after a test. Confirming stable and consistent shunt readings can ensure data integrity in between regular scheduled physical calibration intervals.
  • Cost-effective: Using a shunt calibration resistor is an inexpensive one time investment vs time and cost associated with pre or posttest physical calibrations. This brings the freedom for frequent and quick system calibration checks with minimal equipment down time.
  • Flexibility: Shunt calibration resistors can be used with a wide range of measurement instruments, allowing for greater flexibility in measurement applications. Additionally, many instruments allow shunt resistors to be interchangeable for support of varying sensor outputs.

Overall, shunt calibration resistors are a practical and convenient alternative to physical system calibrations. Shunt calibration resistors can be packaged into all Interface load cells with support across most of the available instrumentation as well. Frequent system health and signal stability checks are vital to ensuring consistent integrity with test data and shunt calibration resistors bring such empowerment for extraordinarily little initial investment.

Contributor: Brian Peters

Additional Resources

Metrologists and Calibration Technicians 101

System Level Calibration Validates Accuracy and Performance

Shunt Calibration for Dummies – Reference Guide

Shunt Calibration 101

Regular Calibration Service Maintains Load Cell Accuracy

Top Five Reasons Why Calibration Matters

 

 

Unlocking the Power of DAQ Webinar

Interface webinar Unlocking the Power of DAQ details trends, best practices and considerations for using data acquisiton in force measurement applications. We explore DAQ instrumentation options, trends and set-up options. Learn why data acquisition systems are growing in popularity for all types of use cases. We also detail the new Interface Data AQ Packs and system options for capturing critical data. Watch the online technical seminar for recommendations on equipment, plus we answser the most frequently asked questions about DAQ in test and measurement.

Testing Lab Essentials Webinar

Interface experts detail standard measurement devices that are essential to all testing labs. They highlight calibration standards and calibration grade equipment, along with instrumentation and data acquisition systems. What types of equipment do you need in the lab to meet the testing demands of today and in the future? Watch this in-depth seminar for recommendations on equipment, best practices, tips, test lab applications and frequently asked questions.