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Operation of Automatic Shaft Speed Controller | Automatic Tank Level Control System | Automatic Teller Machine


An automatic control system is a pre-set closed loop control system that requires no operator action. Most of the closed-loop control systems are automatic in nature. It assumes that the process remains in the normal range for the control system. Various applications of automatic control systems are explained below.


Examples of automatic control system

EXAMPLE 1: Automatic tank-level control system

The control system maintains the water level in a storage tank. The system performs this task by continuously sensing the level in the tank and adjusting a supply valve to add more or water to the tank. The desire level is pre-set by an operator who is not part of this system.


The level transducer measures the level within the tank by using a float and potentiometer arrangement . the level transducer sends a signal representing the tank I,e, feedback to the level control device . this feedback is compared with a desired level to produce the required control action that will position the level control as needed to maintain the desired level. The level control device computes how far to open the supply valve to correct any difference between actual and desired tank levels. diagram of this representing the signal flow to various elements including feedback.

Example 2: Automatic shaft speed control system

Schematic of automatic shaft speed control system. the potentiometer is used to set the voltage to be supplied to the differential amplifier. the differential transducer used as a comparison element which amplifier the feed back signal and it compares the feedback value and reference value.


The differential amplified error signal is fed to a DC motor to adjust the speed of the rotating shaft. The digital tachometer is used as a transducer to measure the speed of the rotating shaft and it is fed back to the amplifier. illustrate working signal flow of this system in block diagram.

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