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CHAPTER 8 DEVELOPMENT IN INSTRUMENTATION & MEASUREMENT, Untitled,…
CHAPTER 8
DEVELOPMENT IN INSTRUMENTATION & MEASUREMENT
Computer-aided measurement and data transmission.
The data can be transmitted over a distant location or from the PC to the mini or mainframe computer.
Data transmission
Parallel transmission
Each bits transmitted simultaneously one line being used for each bit.
Speed of transmission high.
The cost also high due to increased number of wires
serial transmission
Each bits transmitted one by another which all the bits and the position and duration is controlled and keep track of.
Speed of transmission slow.
The cost are less compare to parallel transmission.
FibreOptic Transducer
Optical fibreoptic is a type of sensor which work on the principle of alteration of lightby external variable like motion, pressure, temperature, flow, strain
The fibreact as light conductor
principle
Consists of a thin, low-loss glass wire with a centre/core region.
Core region have a slightly higher refractive index compared than cladding.
A light ray trapped by total reflection at the boundary of the core and total reflection at the boundary of the core and the cladding material.
Depends on:
-> The size of core region
-> Single mode / multimode fibre
The core diameter is very small, D = 50µm.
Advantages
Enhance safety due to its non-metallic construction and absence of high voltages, sparks.
Low weight and small size hence small sensor size.
Compatibility with attached to modern electronic circuit.
Disadvantage
Fragility, requiring careful packaging.
Alignment problems due to small size of optical components.
New technology which cost higher than a normal copper transducer
Applications
Major application is as a medium of data transmission
fibre optic pressure transducer
Fibreoptic accelerometer
Fibreoptic temperature sensor
Fibreoptic flow sensor.
