STATIC AND DYNAMIC CHARACTERISTICS OF INSTRUMENTS - Coggle Diagram
STATIC AND DYNAMIC CHARACTERISTICS OF INSTRUMENTS
Do not change with time are known as
• How closely the instrument measure the actual value.
Accuracy = [(Result - Actual value) / Actual value] x 100
The ability of measurement to produce the sameoutput value on every time.
expressed as the ratio
of the output to the magnitude of the input signal.
Static sensitivity, K = (change of output signal / change in input signal)
No measurement is perfect accuracy and precision.
Error can be classified by:
Systematic or Cumulative Error
– Environmental error
– Loading error
– Instrument error
Miscellaneous Type of Gross Error.
– Human error – observe/ read
– Faulty component/ adjustment
– Improper application of the instrument
Accidental or Random Error.
Presence of of certain system defects
Error = Vi - Va
Vi = indicated value
Va = actual value
the degree of closeness with which a given
value of a quantity is repeatedly measured within a close range.
defined as the variation of output for a given input caused due to change in the sensitivity of a instrument due to certain interfering inputs
can be classified into:
a. Zero drift.
b. Sensitivity drift.
the largest change in input quantity for which a noticeable change in the output quantity is observed from zero reading.
of the instrument.
Instrument’s qualities, value guided.
Accuracy & Precision Characteristic– Sensitivity, linearity, zero
Nature and type of data available– Analog, digital, continuous, etc
Further data computation
Dynamic response characteristic
Susceptibility to environmental disturbancs
Convenience aspects, value judged.
Suitable for the given application– lab use, field use, or both
Adaptibility to different sizes of input– scale expansion, range changes
Safety in use
Maintanance, repair, steady delivery
Material durability & Non-Fouling design
Cost, initial and cumulative total.
• Initial cost– Installation, various attachment, accessories
• Maintainance, repair, calibration
• Running cost
• Expected lifetime
Dynamic characteristic of instruments :
Dynamic characteristic of measuring system:
.applying a known and predetermined input signal to its primary element and the studying the output.
Types of dynamic input signal:
Periodic signal with time period
Varying cyclically with time or repeating itself after a constant interval
-Varying non- cyclically with time
-Sometimes, the signal becomes zero after a certain period of time
-Varying randomly with time, with no definite period and amplitude -may be continues, but not cyclic
Dynamic characteristic can be classified into:
First order System
There is zero mass in the first order system
The elements are the linear spring and viscous damper.
Second order system
The different of second order system with first order system is it consist of a mass
The assumptions are:
The system is a single degree of freedom system.
The restoring element (spring) are linear.
Damping is viscous (consistent).