Functional Elements of an Instrumentation System

FUNCTIONAL ELEMENTS OF AN INSTRUMENTATION SYSTEM

The measurement system consists of several elements or blocks. It is possible to identify four types of element, although in a given system one type of element may be missing or may occur more than once. The four types are shown in Figure 4.1 and can be defined as follows.

Most of the measurement system contains following main functional elements as shown in figure

1. Primary Sensing Element.

2. Variable Conversion Element

3. Variable Manipulation Element

4. Data Transmission Element

5. Data Presentation Element

1. Primary Sensing Element: The measurand is first detected by primary sensing element. The primary sensing element transfers the measurand to variable conversion element for further processing. The output signal of a primary sensing element is a physical variable such as displacement or voltage.

2. Variable Conversion Element: The output signal of a primary sensing element may require to be converted to more suitable variables while preserving its information content. This function is performed by variable conversion element and it may be considered as an intermediate transducer

3. Variable Manipulation Element: This element is an intermediate stage of a measuring system. It modifies the direct signal by amplification, filtering, etc; so that a desired output is produced the physical nature of the variable remains unchanged during this stage.

4. Data Transmission Element: When the functional elements of the measuring system are spatially separated then it becomes necessary to transmit signals from one element to another. This function is performed by data transmission element. It is an essential functional element where remote control operation is desired.

5. Data Presentation Element: Usually information about the quantity being measured is to be communicated to human observer for monitoring control and analysis purpose. This is therefore, to be presented in form of human sensory capability. This function MOX is done by data presentation element.