Metrologia - Sistema de Medição (Parte 1 de 2)

Summary

In this video lesson, Jackson Silva introduces key concepts in metrology, focusing on measuring instruments and systems. He explains the difference between a measuring instrument and a measuring system, outlining the various methods used for measurements, such as comparison, indication, and differential methods. Silva also discusses the components of a measurement system, including sensors, transducers, signal processing, and display devices. He touches on metrological characteristics such as range, scale division, and resolution, highlighting their significance in different measurement instruments, both analog and digital. The video concludes by exploring the importance of understanding these principles in industrial applications.

Takeaways

• 😀 Measuring instruments and measurement systems are terms often used interchangeably, but a measuring instrument is a single device, while a measurement system may include multiple interconnected elements.
• 😀 The comparison method of measurement involves comparing a measurand with a materialized quantity, such as in a plate balance, where mass is determined by equilibrium.
• 😀 Indication is a method where instruments use physical or chemical phenomena (like spring deformation or liquid expansion) to display a value proportional to the measurand.
• 😀 The differential method is commonly used in industry as it is quick, stable, and cost-effective, involving comparing a measurand with a reference dimension, such as with a dial indicator.
• 😀 A measurement system consists of three main modules: a sensor (which interacts with the measurand), a transducer (which converts signals), and an indicator (which displays the information).
• 😀 The sensor in a measurement system is responsible for detecting and generating a signal related to the measurand.
• 😀 Signal processing units are used to amplify or process signals before they are presented to the user, ensuring accurate representation of the measurement.
• 😀 The indication range of a measuring instrument defines the minimum and maximum values it can indicate, like in thermometers or digital displays.
• 😀 The nominal range of an instrument defines the measurement range that can be selected by the user, while the measurement range is the range within which the instrument is designed to measure accurately.
• 😀 Scale division value refers to the difference between consecutive markings on an instrument's scale, while the digital increment is the smallest change in a digital display.
• 😀 The resolution of an instrument is the smallest measurable difference in its output, which may be limited by the scale division for analog instruments or digital increments for digital instruments.

Q & A

What is the difference between a measuring instrument and a measurement system?

A measuring instrument refers to simpler devices like rulers and calipers, typically encapsulated in a single unit. A measurement system is a more generic term that includes multiple interconnected elements used for measurements, such as a control loop with pressure and temperature sensors.

What is the comparison method in measurement?

The comparison method involves measuring a measurand by comparing it with a materialized quantity. An example is a plate balance where mass is measured by comparing two sides until equilibrium is reached, indicating that both sides have the same mass.

How does an indication method work in measuring instruments?

In the indication method, instruments use physical or chemical phenomena to show values proportional to the measurand. For example, in a force measurement device, a spring deforms proportionally to the applied force, and this deformation moves a pointer on a graduated scale.

What is a differential method, and why is it preferred in industry?

The differential method measures the difference between a measurand and a materialized measurement. An example is using a dial indicator to measure the difference between parts. It is preferred in the industry due to its speed, simplicity, stability, and cost-effectiveness.

What are the three main modules that make up a measurement system?

The three main modules are: a sensor transducer, which generates a signal from the measurand; a signal processing unit, which amplifies or processes the signal; and a recording display device, which makes the information perceivable to the user.

How does the signal processing unit work in a measurement system?

The signal processing unit treats the information received from the sensor transducer. This can include amplification of the signal or other processing steps to extract the desired information, such as noise reduction.

Can you explain how a force measuring instrument works with a signal processing unit?

In a force measuring instrument, the spring deforms according to the applied force. The signal from the spring is then processed by a signal processing unit, which amplifies it and makes it readable on an indicator device, such as a digital or analog display.

What is the indication range of a measuring instrument?

The indication range refers to the range of values that the instrument can display, typically defined by the lowest and highest values indicated by the instrument. For example, a thermometer may have an indication range between certain temperature values.

What is the difference between nominal range and measurement range?

The nominal range refers to the range of values that can be selected by the user on a device, while the measurement range is the range for which the instrument is specifically designed to perform accurate measurements.

How is resolution related to scale division and digital increment in measuring instruments?

Resolution refers to the smallest change that can be perceptively measured by the instrument. For digital instruments, resolution equals the digital increment, which corresponds to the scale division. In analog instruments, the resolution can be finer than the scale division, allowing for perception of fractions of a division.