Basic Transmitter Principles Flashcards
Why is a transmitting transducer needed in a large industrial plant?
To convert the measured variable into a transmittable signal
What is a transducer?
Device that receives an input in one physical form and convert it to another form
What three instances will a pneumatic to current transducer be used?
When there is no air available at the controller or receiver
When signals must be transmitted over long distances
When an electrical input signal needs to be transmitted to a computer or data logger
What elements are used to convert pressure to current
Flapper Nozzle arrangement
Bellows
Linear Variable Differential Transformer circuit
Draw and explain the P/I converter
…
What principle does the LVDT
work on?
Mutual inductance
How many coils does the LVDT have? How are they connected and with what method?
It has three coils, one primary coil and two secondary coils which is connected in series opposition method
What does LVDT stand for?
Linear variable differential transformer
Brief explain the core movement
At the initial was of the core voltage induced will be zero if the core is displaced voltage will be induced into the coils resulting in current
What are the two must for transmission media?
It must be instantaneous or nearly so to respond to quick changes in the process variable
It must be compatible with the controller transmitter and final control element
What are the three most common types of transmission media? And state their speed
Pneumatic-fast response which van be improved by conversion to electrical
Electronic- signals travel close to the speed of light
Optical- signals travel at the speed of light
In the 5 happens when the voltage is induced
Due to the resistance of the coil a current is generated
What is FRL
Filter regulator lubricator
Why is FRL important
Since the air hat leaves the compressor is hot wet and dirty it needs to be cleaned to prevent damage and the shorten of the life of downstream equipment
What does live zero do
A live zero of 3psig allows elements of a system to differentiate between a low signal and a system failure (0psig)
