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STATIC AND DYNAMIC CHARACTERISTICS OF INSTRUMENTS - Coggle Diagram
STATIC AND DYNAMIC CHARACTERISTICS OF INSTRUMENTS
CHARACTERISTIC
Error
No measurement
perfect accuracy and pricision
Classified
Accidental or Random Error
Miscellaneous Ty[e Of Gross Error
Systematic or Cumulative Error
SYSTEMATIC/ CUMULATIVE ERROR
Have the same magnitude & sign for a given set of conditions
Example
Loading error
conditions in the area surrounding the instrument
Instrument error
poor design/ instrumentation
Environmental error
by act of measurement on the physical system being tested.
Accidental/ Random Error
Example
Presence of of certain system defects – Change the tolerance
Due to random variations in the parameter or the system of measurement
Miscellaneous Type of Gross Error
Either systematic / random error.
Example
Faulty component/ adjustment
Improper application of the instrument
Human error – observe/ read
Accuracy-Precision
how closely the reading of the instrument approaches the true value
Accuracy of a measuring instrument is expressed as a percentage of the true value of the measured quantity
Accuracy
closely the instrument measure the actual value
Precision
the ability of the instrument to reproduce a certain set of readings within a given accuracy
ability of measurement to produce the SAME output value on every time
Sensitivity
the ratio of the output to the magnitude of the input signal
Reproducibility
the degree of closeness with which a given value of a quantity is repeatedly measured within a close range
the difference between the largest and the smallest result
Drift
the variation of output for a given input caused due to change in the sensitivity of a instrument due to certain interfering inputs like temperature changes
Classified
Zero drift
Sensitivity drift
Dead zone
largest change in input quantity for which a noticeable change in the output quantity is observed from zero reading
due to friction in the instrument
Selection of the instrument
value viewpoints
Instrument’s qualities, value guided
Convenience aspects, value judged
Cost, initial and cumulative total
INSTRUMENT’S QUALITY
ACCURACY & PRECISION CHARACTERISTICS
Sensitivity
linearity
zero
Nature and type of data available
digital
digital
Analog
Further data computation
Dynamic response characteristic
Susceptibility to environmental disturbances
CONVENIENCE ASPECTS
SUITABLE FOR THE GIVEN APPLICATION
lab use
field use
both
ADAPTIBILITY TO DIFFERENT SIZES OF INPUT
scale expansion
range changes
SAFETY IN USE
MAINTENANCE, REPAIR, STEADY DELIVERY
MATERIAL DURABILITY & NON-FOULING DESIGN
COSTS, INITIAL, AND CUMULATIVE TOTAL
INITIAL COST
Installation
various attachment
accessories
MAINTENANCE, REPAIR, CALIBRATION
RUNNING COST
EXPECTED LIFETIME
DYNAMIC CHARACTERISTIC OF INSTRUMENTS
vary over time
determined by applying a known and predetermined input signal to its primary element and the studying the output
Types
PERIODIC SIGNALS WITH TIME PERIOD
Transient signal
Random signal
characteristic
Steady-state periodic
Transient
first order system
linear spring
viscous damper
second order system
mass
assumptions
The restoring element
Damping is viscous
The system is a single degree
