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dynamics: measuring a varying process condition
dynamics: measuring a varying process condition
Instruments hardly respond instantaneously with the changes in the measured variables due to such things as mass, thermal capacitance, fluid capacitance or electrical capacitance.
Delay in instruments is often encountered where the reaction needs time to take place.
Industrial-like instruments that were always used for measuring quantities that will fluctuate with time.
Then, the dynamic and transient behavior of the instrument is important.
Dynamic behavior of an instrument will be determined by subjecting its primary element by to some unknown and predetermined variations in the measured quantity.
The most common variations in the measured quantity
The most common variations in the measured quantity
1. Step change
2. Sinusoidal change
3. Linear change
STEP CHANGE
STEP CHANGE
Primary element is subjected to an instantaneous and finite change in measured variable.
SINUSOIDAL CHANGE
SINUSOIDAL CHANGE
Primary element follows a measured variable, the magnitude of which changes in accordance with a sinusoidal function of constant amplitude.
LINEAR CHANGE
LINEAR CHANGE
Primary element is following the measured variable, changing linearly with time.
THE DYNAMIC PERFORMANCE CHARACTERISTICS OF AN INSTRUMENT
SPEED OF RESPONSE
The speed with which an instrument reacts to changes in the quantity being measured.
DYNAMIC ERROR
With no static error, the difference between the true and measured value.
FIDEBLITY
The degree to which a measurement equipment accurately reflects changes in the measured variable.
LAG
Delay in an instrument's response to change in the measured variable.
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