KNOWLEDGE SHARING PROGRAM
Topic- Basic Instrumentation
-:by:Mohammad Zulfequar Ali Khan
Dy. Manager -Quality E&I
(3.0 MTPA Blast Furnace Project, Nagarnar)
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Instrumentation is defined as the art and
science of measurement and control of
process variables within a production or
manufacturing area.
In the Process plant Instrumentation involves following basic elements
 Sensing & Measuring:- Measuring of process variable, Such as Flow,
Temperature, Pressure and Level is done by measuring device like
Orifice, RTD, Thermocouple,Pressure Gauge, Temperature gauge and
Transmitters.
 Transmitting :- Measuring the process variable at the accuracy
required and transmitting the controller for further manipulation.
 Controller:- Device that controls output for final control element
based on input and set point requirement.
 Final Control :- Done by final control element such as control valves
motor. Final control element restrict or allows the process as per the
output of the controller
Sensing
Measuring
Transmitti
ng
Controlling
Final Control
Element
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Process Value/Variable(PV):- The measured
value of the Process system.
Set Value/Variable(SV):- The desired value
of the controlled variable(required process
value).
Manipulated Value/Variable(MV) :-The
process variable being adjusted by the
controller to maintain the controlled
variable at the set point.
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Transmitters are devices which sense the
mechanical value converts it into electrical
value and transmit it to control station and
also it display the process value locally for
operators.
A Transmitter is a device that produces an
output signal, often in the form of a 4–
20 mA electrical current signal
Transmitter =
Sensor+Convertor(Transducer)+Display
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In Process industry transmitters are
categories broadly in 4 Part
Pressure transmitter (PT)
Flow Transmitter (FT)
Level transmitter (LT)
Temperature Transmitter (TT)

A Pressure transmitter is a device which sense
the process pressure with help of diaphragm
and convert mechanical effect into electrical
signal with the help of transducer and then
transmit in 4-20 ma analog signal to
controller.

A Flow transmitter is a device which sense the
process flow with help of flow measuring
devices and convert mechanical effect into
electrical signal with the help of transducer
and then transmit in 4-20 ma analog signal
to controller.

A Level transmitter is a device which sense
the process level in a closed or open vessels
with help of level measuring devices and
convert mechanical effect into electrical
signal with the help of transducer and then
transmit in 4-20 ma analog signal to
controller.

A Temperature transmitter is a device which
sense the process temperature with help of
temperature measuring devices and convert
the temperature effect into electrical signal
with the help of transducer and then transmit
in 4-20 ma analog signal to controller.
THANKS