Glossary of Terms

Accuracy

Stated as a limit tolerance which defines the average deviation between the actual output versus theoretical output. In practical, transducer applications, the potential errors of nonlinearity, hysteresis, non-repeatability and temperature effects do no normally occur simultaneously, nor are they necessarily additive. Accuracy is calculated based upon the RMS value of potential errors, assuming a temperature band of +/- 10°F, full rated load applied, and proper set up and calibration. Potential errors of the readout, crosstalk, or creep effects are not included.

Ambient conditions

The conditions (humidity, pressure, temperature, etc.) of the medium surrounding the transducer.

Ambient temperature

The temperature of the medium surrounding the transducer.

Angular load, concentric

A load applied concentric with the primary axis at the point of application, and at some angle with respect the primary axis.

Angular load, eccentric

A load applied eccentric with the primary axis at the point of application, and at some angle with respect the primary axis.

Apparent strain

Observed deformation or strain measured at the surface of a material or structure, typically using non-contact measurement techniques such as optical methods or strain gauges. It may differ from the true or actual strain experienced within the material due to factors such as surface irregularities, material heterogeneity, or local stress concentrations. Apparent strain measurements are useful for assessing surface-level deformation but may require correction or validation against more accurate methods for comprehensive analysis.

Axial load

A load applied along a line concentric with the primary axis.

Bridge Circuit

A bridge circuit is an electrical network used to measure and detect small changes in resistance, capacitance, or inductance. The most common type is the Wheatstone bridge, consisting of four resistive arms connected in a diamond configuration. It is widely used in instrumentation and sensor applications to accurately measure physical quantities such as strain, force, or pressure by detecting changes in resistance.

Bridge Factor

The bridge factor, also known as the gauge factor, is a dimensionless quantity that represents the ratio of the change in electrical resistance of a strain gauge to the applied mechanical strain. It characterizes the sensitivity of the strain gauge to strain-induced changes in resistance and is typically provided by the manufacturer as a calibration parameter for accurate strain measurements in strain sensing applications, such as load cells or force sensors utilizing Wheatstone bridge configurations.

Calibration

The comparison of transducer outputs against standard test loads.

Calibration constant

Calibration constant, also known as sensitivity coefficient or calibration factor, is a numerical value used to convert sensor output into corresponding physical units. It represents the relationship between the sensor's output signal and the actual value being measured. Calibration constants are determined through calibration procedures and are essential for accurately interpreting sensor readings in real-world applications.

Calibration curve

A record graph of the comparison of transducer outputs against standard test loads.

Combined errors – nonlinearity and hysteresis

The maximum deviation from the straight line drawn between the original no-load and rated load outputs expressed as a percentage of the rated output and measured on both increasing and decreasing loads.

Compensation

The utilization of supplementary devices, materials, or processes to minimize know sources of errors.

Creep

The change in transducer output occurring with time, while under load, and with all environmental conditions and other variables remaining constant. Usually measured with rated load applied and expressed as a percent of rated output over a specific period of time.

Creep Recovery

The change in no-load output occurring with time, after removal of a load which has been applied for specific period of time.

Crosstalk

With one component loaded to capacity, and the other unloaded, the output of the unloaded component will not exceed the percentage specified of its full scale capacity.

DAQ

"DAQ" typically stands for "Data Acquisition." Data acquisition refers to the process of measuring, recording, and analyzing physical phenomena or signals in the form of electrical or physical quantities and converting them into digital data that can be processed by a computer.

A data acquisition system typically consists of several components, including:

Sensors/Transducers: These are devices that convert physical phenomena (such as temperature, pressure, or light intensity) into electrical signals.

Signal Conditioning: In many cases, the electrical signals from sensors need to be conditioned or amplified before they can be accurately measured. Signal conditioning circuits perform tasks such as amplification, filtering, and isolation to ensure the signals are suitable for measurement.

Data Acquisition Hardware: This includes the physical components used to interface with the sensors, such as analog-to-digital converters (ADCs) for converting analog signals into digital data, and digital input/output (I/O) modules for interfacing with external devices.

Data Acquisition Software: Software is used to control the data acquisition hardware, acquire and record data, perform real-time analysis, and visualize the results. This software may be provided by the manufacturer of the data acquisition hardware or developed independently.

Data acquisition systems are used in a wide range of applications across various industries, including industrial automation, scientific research, environmental monitoring, automotive testing, and more. They provide valuable insights into the behavior of physical systems and help researchers and engineers make informed decisions based on data.

Deflection

The change in length along the primary axis of the load cell between no-load and rated load conditions.

Dielectric

A random change in Output under constant Load conditions.

Drift

A dielectric is an insulating material that does not conduct electric current when subjected to an electric field. Dielectrics are characterized by their ability to store electrical energy in an electric field and are commonly used in capacitors and insulation applications to prevent the flow of electricity.

Eccentric Load

Any load applied parallel to, but not concentric with, the primary axis.

Error

The algebraic difference between the indicated and true value of the load being measured.

Excitation, electrical

The voltage or current applied to the input terminals of the transducer.

Fatigue capacity

Capacity as a percentage of the nominal load limit capacity, and based on 100 x 106 cycles (minimum) from zero to full fatigue capacity and 50 x 106 cycles (minimum) from full fatigue capacity tension to full fatigue capacity compression load.

Finite Element Analysis 

A computational method used to simulate and analyze the behavior of complex structures and systems under various loading conditions. It subdivides the structure into small, finite-sized elements and uses mathematical techniques to model their behavior based on physical properties and boundary conditions. FEA is widely used in engineering and design to predict stresses, strains, displacements, and other characteristics, aiding in the optimization and validation of designs before physical prototyping or manufacturing.

Force Sensor

A transducer detecting and quantifying the force applied to it. Utilizing various principles like piezoelectricity or strain gauges, force sensors deliver precise measurement of tension, compression, or shear forces in mechanical systems, critical for advanced engineering analyses and control systems.

Hysteresis

The maximum difference between the transducer output readings for the same applied load; one reading obtained by increasing the load from zero and the other by decreasing the load from rated load. Note: Usually measured at half rated output and expressed in percent of rated output. Measurements should be taken as rapidly as possible to minimize creep.

Insulation resistance

The DC resistance measured between the transducer circuit and the transducer structure. Note: Normally measured at fifty volts DC and under standard test conditions.

Load

The weight, torque, or force applied to the transducer.

Load cell

A device which produces an output signal proportional to the applied weight or force.

Multi axis sensor

A sensor capable of measuring forces or motions along multiple orthogonal axes simultaneously. Employing advanced sensing elements like accelerometers or gyroscopes, multi-axis sensors offer comprehensive data on complex spatial movements, vital for precise motion control, inertial navigation, and aerospace applications.

Natural frequency

The frequency of free oscillation under no-load conditions.

NIST

NIST, the National Institute of Standards and Technology, is a federal agency under the U.S. Department of Commerce. It develops and maintains standards, conducts research, and provides guidance to advance measurement science, technology, and cybersecurity, fostering innovation and industrial competitiveness in the United States.

NIST Traceable

NIST Traceable refers to measurements or standards that have been calibrated against or certified by the National Institute of Standards and Technology (NIST). This ensures the accuracy and reliability of measurements by providing a documented chain of comparisons to NIST standards, enhancing confidence in measurement accuracy and consistency.

Nominal load limit capacity

It is designed normal maximum capacity of a transducer is based on this capacity unless specified.

Nonlinearity

The maximum Deviation of the Calibration Curve from a straight line drawn between the no-load and Rated Load outputs, expressed as a percentage of the Rated Output and measured on increasing load only.

Occlusion

Occlusion refers to the blocking or obstruction of a passage or opening, typically by a solid object or substance. In medical contexts, it can refer to the blockage of blood vessels, airways, or other bodily passages. In sensor applications, occlusion can occur when an object obstructs the sensing element, affecting the accuracy or reliability of measurements.

Oscillator

An oscillator is an electronic circuit or device that generates a periodic, repetitive waveform, typically in the form of a sine wave, square wave, or triangular wave. Oscillators are fundamental components in electronics and are used in a wide range of applications, including signal generation, clock generation, frequency synthesis, and timing circuits.

Oscillators operate based on the principle of feedback, where a portion of the output signal is fed back to the input to sustain oscillation. This feedback loop is often achieved using active components such as transistors, operational amplifiers, or integrated circuits.

There are various types of oscillators, each with its own circuit configuration and operating principles. Some common types include:

RC Oscillator: Uses a combination of resistors and capacitors to set the oscillation frequency.

LC Oscillator: Relies on inductors and capacitors to determine the oscillation frequency, commonly found in radio frequency (RF) applications.

Crystal Oscillator: Utilizes the mechanical resonance of a piezoelectric crystal to produce a stable frequency output, commonly used in digital clocks, microcontrollers, and communication systems.

Voltage-Controlled Oscillator (VCO): Generates an output frequency that can be controlled by an input voltage, making it suitable for frequency modulation (FM) and phase-locked loop (PLL) circuits.

Relaxation Oscillator: Produces a square or pulse waveform by charging and discharging a capacitor through a resistor, commonly used in timer circuits and pulse generators.

Oscillators play a crucial role in modern electronics, providing timing references and stable frequency sources essential for various electronic systems and devices. They are found in applications ranging from simple electronic gadgets to sophisticated communication systems and high-speed digital circuits.

Output

This signal (voltage, current, etc.) produced by the transducer. Where the output is directly proportional to excitation, the signal must be expressed in terms of volts per volt, volts per ampere, etc. of excitation.

Output, rated

The algebraic difference between the outputs at no-load and at rated load.

Overload rating

The maximum load in percent of rated capacity which can be applied without producing a permanent shift in performance characteristics beyond those specified. Overload static rating ultimate extraneous limit. Only one ultimate static extraneous load limit (200% of Static Extraneous Load Limit (F or F or M or M or M) can be applied simultaneously with 100% of the nominal load limit capacity without producing a structural failure.

Piezoelectric

The term "piezoelectric" refers to a property exhibited by certain materials whereby they generate an electric charge in response to mechanical stress or pressure. Conversely, they can also experience mechanical deformation or vibration when subjected to an electric field. This phenomenon is known as the piezoelectric effect.

Piezoelectric materials are crystalline in nature, and they have asymmetric crystal structures, which means their positive and negative charges are not evenly distributed within the crystal lattice. When a mechanical force is applied to such a material, it causes a displacement of ions within the crystal lattice, resulting in a separation of charges and the generation of an electric potential across the material. Similarly, when an electric field is applied to the material, it causes the material to deform or vibrate due to the movement of ions.

Piezoelectric materials find a wide range of applications due to their unique properties. Some common uses include:

Sensors: Piezoelectric materials are used in various types of sensors, such as pressure sensors, accelerometers, and force sensors, where they convert mechanical signals into electrical signals for measurement.

Actuators: They are also employed in actuators, devices that convert electrical energy into mechanical motion. Piezoelectric actuators are used in precision positioning systems, ultrasonic motors, and micro-positioning applications.

Transducers: Piezoelectric transducers are utilized in ultrasonic devices for medical imaging (ultrasound), industrial cleaning, and distance measurement.

Energy Harvesting: Piezoelectric materials can convert mechanical vibrations or movements into electrical energy, making them suitable for energy harvesting applications, such as powering small electronic devices or sensors in remote locations.

Filters and Oscillators: Piezoelectric resonators are used in electronic circuits as stable frequency sources for timing and filtering applications.

Overall, piezoelectric materials play a crucial role in various technological advancements and continue to find new applications across different fields.

Potentiometer

A potentiometer, often referred to as a "pot," is a type of variable resistor used to control electrical resistance in a circuit manually. It consists of a resistive element, typically a long, narrow strip of resistive material, with a movable contact called a wiper that can be adjusted along its length.

The potentiometer has three terminals: two fixed ends of the resistive element and one terminal connected to the wiper. By turning a knob or shaft attached to the wiper, the resistance between the wiper terminal and one of the fixed terminals can be varied. This adjustment changes the voltage division across the resistive element.

Potentiometers are commonly used in various electronic circuits for tasks such as volume control in audio equipment, brightness control in displays, and tuning circuits in radios. They offer a simple and cost-effective means of adjusting voltage or controlling parameters in a circuit manually. Additionally, potentiometers come in various types, including rotary (knob) potentiometers and slide potentiometers, to suit different application needs.

Primary axis

The axis along which the transducer is designed to be loaded; normally its geometric centerline.

Rated capacity (Rated load)

The maximum axial load that the transducer is designed to measure within its specifications.

Rated Output

Rated output refers to the specified electrical signal produced by a transducer-based sensor when subjected to its rated input or operating conditions. It represents the expected magnitude of the electrical output signal corresponding to the maximum rated input of the sensor, typically expressed in terms of voltage, current, or digital data.

Rectifier

A rectifier is an electronic device used to convert alternating current (AC) into direct current (DC). It allows current to flow in one direction while blocking it in the opposite direction. Rectifiers are essential components in power supplies for various electronic devices and systems, as many electronic devices operate on DC power.

There are several types of rectifiers, including:

Half-Wave Rectifier: This type of rectifier uses a single diode to convert only one half of the AC input waveform to DC. It is the simplest form of rectifier but is not very efficient because it only uses half of the input power.

Full-Wave Rectifier: Full-wave rectifiers use two or four diodes to convert both halves of the AC input waveform to DC. This results in a more efficient conversion compared to half-wave rectifiers. There are two main types of full-wave rectifiers: center-tapped and bridge rectifiers.

Center-Tapped Full-Wave Rectifier: This configuration uses a center-tapped transformer and two diodes to form two separate rectifier circuits. It produces a higher output voltage compared to a bridge rectifier but requires a larger and more expensive transformer.

Bridge Rectifier: A bridge rectifier uses four diodes arranged in a bridge configuration to rectify the AC input. It does not require a center-tapped transformer and is more commonly used in practical applications due to its simplicity and efficiency.

Bridge Rectifier with Capacitor Filter: In many applications, a capacitor filter is added to the output of the rectifier to smooth out the pulsating DC voltage produced by the rectification process. This capacitor filter helps reduce the ripple voltage and produces a more stable DC output.

Rectifiers are found in a wide range of electronic devices and systems, including power supplies for consumer electronics, industrial equipment, and telecommunications infrastructure. They play a crucial role in converting AC power from the grid into the DC power needed to operate electronic devices reliably.

Reference standard

A force measuring device whose characteristics are precisely known relative to a primary standard.

Repeatability

The maximum difference between transducer output readings for repeated loadings under identical loading and environmental conditions.

Resolution

The smallest change in mechanical input which produces a detectable change in the output signal.

Rheostat

A rheostat is a type of variable resistor used to control the flow of electric current in a circuit by varying the resistance. Unlike a potentiometer, which typically has three terminals and is used to divide voltage, a rheostat usually has only two terminals and is designed to regulate current.

Rheostats consist of a resistive wire wound on an insulating core, often in a coil or spiral shape, with a sliding contact or wiper that can move along the length of the wire. As the wiper is adjusted, the amount of wire in the circuit through which current can flow changes, altering the total resistance and thus controlling the current.

Rheostats are commonly used in applications where precise current control is required, such as in lighting dimmer switches, motor speed control, and laboratory equipment. However, due to their design and the need for physical movement to adjust them, they are less commonly used in modern electronic circuits compared to other types of electronic components like transistors or integrated circuits. Instead, electronic circuits often utilize digital methods for controlling current or voltage.

Safe Overload Rating

Safe overload rating refers to the maximum load or stress that a device or equipment can tolerate temporarily, beyond its rated capacity, without sustaining permanent damage or compromising safety. It is a specified margin of safety designed to accommodate short-term overloads while maintaining structural integrity and functionality within acceptable limits.

Sensitivity

The ratio of the change in output to the change in mechanical input.

Shunt calibration

Electrical simulation of transducer output by insertion of known shunt resistors between appropriate points within the circuitry.

Shunt-to-Load correlation

The difference in output readings obtained through electrically simulated and actual applied loads.

Standard test conditions

The environmental conditions under which measurements should be made, when measurements under any other conditions may result in disagreement between various observers at different times and places.

Strain

Strain is a measure of the deformation or change in shape experienced by a material in response to an applied stress. It is typically defined as the ratio of the change in length or dimension of the material to its original length or dimension. Strain can be expressed as a dimensionless quantity or as a percentage.

Strain Gauge

An electrical resistance-based sensor affixed to an object to quantify its mechanical strain. It operates on the principle of piezoresistance, exhibiting altered resistance proportional to strain, enabling precise measurement of stress and deformation in structural components and materials

Stress

The force applied per unit area on a material or structural component. It is typically measured in units of pressure, such as pascals (Pa) or pounds per square inch (psi), and can result from external forces, thermal effects, or other factors.

Stress Relaxation

Stress relaxation is the gradual decrease in internal stress within a material over time when subjected to a constant strain or deformation. Unlike creep, which involves deformation under constant load, stress relaxation occurs when the material undergoes a constant deformation, leading to a reduction in internal stress levels. This phenomenon is commonly observed in viscoelastic materials such as polymers and certain metals, and it can affect the mechanical behavior and performance of materials over time.

Temperature effect on output

The change in output due to a change in transducer temperature. Usually expressed as a percentage of load per degree Fahrenheit change temperature.

Temperature effect on zero balance

The change in zero balance due to a change in transducer temperature. Note: Usually expressed as the change in zero balance in percent of rated output per degrees Fahrenheit (change in temperature).

Temperature range, compensated

The range of temperature over which the transducer is compensated to maintain rated output and zero balance within specified limits.

Temperature range, safe

The extremes of temperature within which the transducer will operate without permanent adverse change to any of its performance characteristic.

Terminal resistance, excitation

The resistance of the transducer circuit measured at the excitation terminal, at standard temperature, with no-load applied, and with excitation and output terminals open-circuited.

Terminal resistance, signal

The resistance of the transducer circuit measured at the output signal terminals, at standard temperature, with no-load applied, and with the excitation terminals open-circuited.

Thermistor

A thermistor is a type of resistor whose electrical resistance varies significantly with temperature. The word "thermistor" is a combination of "thermal" and "resistor". Thermistors are made from semiconductor materials with a high temperature coefficient of resistance, meaning their resistance changes substantially with temperature variations.

There are two main types of thermistors:

Negative Temperature Coefficient (NTC) Thermistors: In NTC thermistors, the resistance decreases as the temperature increases. This type of thermistor is commonly used in temperature sensing applications such as temperature control in electronic devices, temperature compensation, and overcurrent protection.

Positive Temperature Coefficient (PTC) Thermistors: In PTC thermistors, the resistance increases as the temperature increases. PTC thermistors are often used in applications like self-regulating heaters, overcurrent protection, and motor starting circuits.

Thermistors offer several advantages for temperature sensing compared to other temperature sensors, including a relatively small size, fast response time, and high sensitivity. They are widely used in various industries, including automotive, consumer electronics, medical devices, and industrial automation, for precise temperature measurement and control.

Thermocouple

A thermocouple is a type of temperature sensor that consists of two different conductive materials joined together at one end. When there is a temperature gradient along the length of the joined materials, it creates a voltage difference proportional to the temperature difference. This phenomenon is known as the Seebeck effect. Thermocouples are commonly used for temperature measurement in various industrial, scientific, and consumer applications due to their simplicity, durability, wide temperature range, and relatively low cost. They are often employed in situations where other types of temperature sensors may not be suitable, such as in high-temperature environments or where fast response times are needed.

Torque Sensor

A sensor gauging the rotational force or torque exerted on a system. Employing technologies such as strain gauges or magnetoelasticity, torque sensors provide high-precision measurements crucial in automotive testing, industrial robotics, and machinery monitoring for performance optimization and safety assurance.

Traceability

The step-by-step transfer process by which the transducer calibration can be related to primary standards.

Ultimate Overload Rating

Ultimate overload rating refers to the maximum load or stress that a device or equipment can withstand before experiencing catastrophic failure or permanent damage. It represents the absolute limit beyond which the structural integrity of the device is compromised, rendering it inoperable or unsafe for further use.

Wheatstone Bridge

A Wheatstone Bridge is an electrical circuit consisting of four resistive legs arranged in a diamond shape. One or more legs may contain an active sensing element. It functions akin to two parallel voltage divider circuits. Physical effects, like strain on a sensor, alter the resistance of the sensing elements.

Zero balance

The output signal of the transducer with rated Excitation and with no-load applied, usually expressed in percent of Rated Output.

Zero return

The difference in zero balance measured immediately before Rated Load application of specified duration and measured after removal of the load, and when the output has stabilized.

Zero shift, permanent

A permanent change in the no-load output.