Jul 7, 2011

Understanding the Role of Instrumentation in Automation

In almost all the Major Industries and plants, Instrumentation is the thing with which we need to see on every day basis. Instrumentation plays a key role in the smooth operation of any Plant. So every automation engineer should understand and Analise the aspects of Instrumentation.

Instrumentation - The controlling Power :-

What is Instrumentation? Instrumentation is the art of measuring the value of some plant parameter. Every plant has the need of measuring some process parameter as temperature , flow or level. These instruments process these parameters and then a provide a proportional output accordingly. The most common output form are 0 to 10 V , 4 to 20mA and 20-100 kPa pneumatic signal.

In this series of tutorials we will see that how the different plant parameters are measured with the help of Instruments. As a PLC Programmer we are always interested in getting the analog Input , but this time we will go one step back and try to understand the Instrumentation.

Pressure Measurement Device Working :-

In this Section we will try to understand the operation of Pressure Detectors bourdon tubes, diaphragms, bellows, forced balance and variable capacitance. Pressure is the parameter which is of utmost importance in power plants. In all power plant the value of pressure is measured at various stages such as steam pressure, feed water pressure, condenser pressure, lubricating oil pressure and many more.Pressure is actually the measurement of force acting on area of surface.

Pressure = Force / Area
The unit of pressure is pounds per square inch (PSI) in British units or Pascals (Pa) in metric. As one PSI is approximately 7000 Pa, we often use kPa and MPa as units of pressure.

How Pressure Value is Measured by Instruments :-

The main objective or principle by which instruments measure the value of pressure is produce a dial indication, control operation or a standard (4 - 20 mA) electronic signal that represents the pressure in a process.
Most of the sensors produce a linear motion respective to the pressure applied and this we get to know about the value of acting pressure.

In our next part we will see about the operating principle of different types of pressure transmitters and Instruments. Till then you can subscribe to get all latest updates.Subscribe to Automation-Talk by Email.

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