Measurement technology is used in many areas. Whether in electrical engineering, mechanical engineering, medicine, chemistry or environmental technology, applied measurement technology plays a major role.
In this article, you will learn about the basic terminology and the tasks of measurement technology.
Tasks of measurement technology
In the field of industrial measurement technology, the achievement of new findings in the course of scientific developments is often overlooked. In addition to traditional metrological activities such as testing, calibrating, adjusting or verifying, science is using metrology to research the further technical development of measurement processes.
This enables improvements to be made in environmental protection or telecommunications, for example. The use of special and increasingly precise measuring methods makes it possible to detect and eliminate faults.
The task of measurement technology can generally be described by three characteristics:
- Measurement technology is not objective. Measuring must therefore be distinguished from estimating.
- Metrological activities are repeatable, controllable and can be reproduced.
- All measurement results are marked with a number.
Digitalization is also advancing in the field of measurement technology.
Electrical measuring methods are being used more and more. Nowadays, non-electronic variables are also determined by digital measuring systems.
Electrical measuring methods offer many advantages. The measured values can be recorded without a great deal of effort. In addition, the high resolution, the fast and simple processing of the measurement data and the good transmission capability are further important advantages in the digital age.
Typical measurement technology activities
The actual measurement is dedicated to the determination of a measured variable multiplied by a unit. However, there are other typical activities that must be distinguished from standard measuring.
We speak of testing when we determine whether the measured object fulfills one or more conditions. In other words, the result is always reflected in a yes/no decision. Are certain requirements met? The activity of testing deals with this type of question. Examples here are the testing of resistance values of certain resistors within a tolerance limit.
By definition: Calibration is the determination of the measurement deviation, i.e. the correlation between the output value and the true value of a measured variable. This checks whether the measuring system complies with the promised accuracy. A table can be drawn up to correct systematic deviations. During calibration, the reference value is determined using a standard. The reference measuring device is called Normal.
The measuring device is calibrated during adjustment. The aim of an adjustment is to reduce measurement deviations. The difference between calibration and adjustment is that during adjustment, for example, a precisely known voltage is applied and measured at the same time as the standard. The adjustment elements are changed until the display value matches the reference value as closely as possible.
Calibration is often associated with official authorities. In simple terms, calibration is the testing of measuring devices in accordance with legal regulations and requirements. If a measuring device complies with all requirements, a calibration certificate is issued. Many measuring instruments are subject to calibration, especially in commercial transactions. Calibration is most frequently used for scales or gas flow meters.
In the following, some basic terms of measurement technology, or metrology (the science of measurement) are explained.
The measurand is the physical quantity that is to be determined by the measurement. For example, the resistance value, energy, voltage or direct current can be determined.
Standards and guidelines are not necessarily popular. However, they have the important purpose of describing the state of the art and thus support the safety and quality of products and services. They are regarded as the basis for international trade.
A measuring device is the device required to measure a measurand. The measuring device contains a display that shows the measured value. The measured variable can also be transformed or processed by the measuring device in the same way as a current-voltage transformer does, for example.
A measuring system is a system consisting of one or more measuring devices together with the equipment required for measurement. These facilities include, for example, the energy supply. A digital voltmeter or a calibration device are examples of such measuring devices.
The transducer is also commonly referred to as a sensor or measuring probe. It is part of the measuring device or the measuring system. The sensor responds directly to the physical variable. The output signal of the sensor is further processed and output. Examples of such sensors are current sensing resistors or Hall sensors for power measurement.
The measured value is an explicitly measured value of a measured variable. It is given as a numerical value multiplied by a unit. For example, this could be 223.2 V as a measured voltage value.
The true value
The true value is the uniquely existing value of the measured variable. The target of the measurement, so to speak. As a rule, the true value cannot be determined. External circumstances, influences or repercussions do not permit recording. The measured value is virtually falsified by these influences on the measuring device itself.
The measurement deviation is the difference between the measured value and the true value. The aim of calibration is to record this measurement deviation.
The result of a measurement can be a single measured value or determined from several measured values. Special calculation rules apply here. If necessary, individual measured values are also corrected.
The measurement uncertainty forms an interval around the measured value in which the true value lies with a certain probability. For a certain measured value x with a measurement uncertainty u , the true value lies in the interval x±u.
Traceability is a property of a measurement result which is characterized by being related to corresponding national standards through an uninterrupted chain of comparisons. Traceability in accordance with ISO 9000 is mandatory. Compliance with quality assurance is checked in specific audits by independent and accredited companies. If this test is passed, the respective quality assurance system receives certification. For ISO certification, measuring equipment must therefore be calibrated with standards that are traceable to international or national standards.
Measuring and testing have been part of everyday life since time immemorial. These are activities that are of great benefit to science, trade and industry. They are also indispensable for global cooperation.
We hope we have been able to give you a brief but instructive insight into the tasks and basics of measurement technology.