Answer / s.sasikumar

the above is correct. in auto tuning the parameters of
P,I,D values varies automatically with respect to feedback
values and it takes several hours to be in stable at
setpoint where in manual the operator has to give the P,I,D
values manually by taking the response in graph as per
zeigler-nichols method . And it consumes half of the time
to be in stable at the set point when compared to auto
tuning.

Answer / mahesh kumar

In Autotuning the loop (PID, PIED etc.)are tuned with help
of the S/W, only by pressing the autotune button the S/W
autometically tune the gains while manual tuning the
programmer set all the gains manually. Manual Tuning is
just like hit & Trial Process.

A PLC is programmed to drive three motors A, B and C as follows : After running motor A for an hour, motor B should get ON and motor A should get OFF. And after running motor B for an hour, motor C should get ON and motor B should get OFF. And after running motor C for an hour, motor A should get ON and motor C should get OFF. (That is, a cyclic repetition with time period one hour) Now, the second condition is: If any motor gone faulty and is tripped, the consecutive motor should get ON and the faulty (tripped) motor should be eliminated from cyclic repetition. The remaining two motors should bear the cyclic repetition of one hour each. (For healthy motor take logic as high and for tripped motor take logic as low) Now, the third condition is: When motor A load(Amps) exceeds 60% of its rated load, motor B should get ON in parallel to motor A. And when both motors A & B are running in parallel, and if their load exceeds 60% of their rated load, motor C should also start in parallel to A & B. [Here the cyclic repetition is eliminated, until their loads become normal(40%)] [Take logic high(1) for load at 60% and logic low(0) for load at 40%] Now draw a flow chart or a ladder diagram to fulfill the above condition.

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